WO1993003861A1

WO1993003861A1 - Processes and applications for transition metal oxide coated substrates

Info

Publication number: WO1993003861A1
Application number: PCT/US1992/006758
Authority: WO
Inventors: Thomas J. Clough; Victor L. Grovesnor; Naum Pinsky
Original assignee: Ensci, Inc.
Priority date: 1991-08-12
Filing date: 1992-08-08
Publication date: 1993-03-04

Abstract

Processes for coating three dimensional inorganic substrates, with shielded surfaces, with transition metal oxide-containing coatings are disclosed. Such processes comprise contacting a substrate with a transition metal oxide precursor, preferably maintaining the precursor coated substrate at conditions to equilibrate the coating, and then oxidizing the precursor to form a substrate containing transition metal oxide on at least a portion of the three dimensions and shielded surfaces of the substrate. Also disclosed are substrates coated with transition metal oxide-containing coatings for use in various applications including catalysis, shielding, heating and electro rheological applications using elements such as inorganic, fluid, porous and polymer matrix elements.

Description

PROCESSES AND APPLICATIONS FOR TRANSITION METAL OXIDE COATED SUBSTRATES

Technical Field

The present invention relates to a process for coating substrate and to applications and uses thereof. Mo particularly, the invention relates to coating an inorgan substrate with a transition metal oxide-containing materia such material being an electrically conductive and/ ferromagnetic oxide-containing material. Background Art

In many electronic and/or ferromagnetic applications i would be advantageous to have an electrically, electronicall conductive; electro mechanical and/or ferromagnetic transitio metal oxide coating which is substantially uniform, has hig and/or designed electronic conductivity, and/or ferro magneti properties and has good chemical properties, e.g., morphology stability, etc.

A number of techniques have been employed to provid certain transition metal oxide coatings on substrates. Fo example, a chemical vapor deposition (CVD) process has bee employed. Conventionally, the CVD process occur simultaneously at high temperatures at very short contact time so that transition metal oxide is initially deposited on th substrate. However transition metal oxide can form off th substrate resulting in a low reagent capture rate. The CV process is well known in the art for coating a single fla surface which is maintained in a fixed position during th above-noted contacting steps. The conventional CVD process i an example of a "line-of-sight" process or a "two dimensional process in which the transition metal oxide is formed only o that portion of the substrate directly in the path of th transition metal source as transition metal oxide is formed o the substrate. Portions of the substrate, particularl internal surfaces, which are shielded from the transition meta oxide being formed, e.g., such as pores or channels whic extend inwardly from the external surface and substrate layer which are- internal at least partially shielded from th depositing transition metal oxide source by one or more othe layers or surfaces closer to the external substrate surfa being coated, do not get uniformly coated, if at all, in ¹¹line-of-sight" process. Such shielded substrate portio either are not being contacted by the transition metal sour during line-of-sight processing or are being contacted, if all, not uniformly by the transition metal source during lin of-sight processing. A particular problem with "line-of-sigh processes is the need to maintain a fixed distance between t source and the substrate. Otherwise, transition metal dioxi can be deposited or formed off the substrate and lost, with corresponding loss in process and reagent efficiency.

The prior art processes described below follo conventional processing techniques such as by sintering of transition metal oxide and/or the instantaneous conversion t transition metal oxide by spray pyrolysis.

For example in "Preparation of Thick Crystalline Films o Tin Oxide and Porous Glass Partially Filled with Tin Oxide," R G. Bartholomew et al, J. Electrochem, Soc. Vol. 116, No. 9 pl205(1969), a method is described for producing films of Sn0 on a 96% silica glass substrate by oxidation of stannou chloride. The plates of glass are pretreated to remov moisture, and the entire coating process appears to have bee done under anhydrous conditions. Specific electrica resistivity values for Sn0₂-porous glass were surprisingl high. In addition, doping with SbCl₃ was attempted, bu substantially no improvement, i.e., reduction, in electrica resistivity was observed. Apparently, no effective amount o antimony was incorporated. No other dopant materials wer disclosed. In "Physical Properties of Tin Oxide Films Deposited b Oxidation of SnCl₂," by N. Srinivasa Murty et al, Thin Soli Films, 92(1982) 347-354, a method for depositing Sn0₂ films was disclosed which involved contacting a substrate with a combined vapor of SnCl₂ and oxygen. Although no dopants were used, dopant elements such as antimony and fluorine were postulated as being useful to reduce the electrical resistivity of the Sn0₂ films. Dislich, et al U. S. Patent 4,229,491 discloses a process for producing cadmium stannate layers on a glass substrate. The process involved dipping the substrate into an alcoholic solution of a reaction product containing cadmium and tin metal; withdrawing the substrate form the solutio in a humid atmosphere; and gradually heating the coated substrate to 650°C whereby hydrolysis and pyrolysis remove residues from the coated substrate.

In "Thin-film surface-acoustic-wave devices." Mitsuyu, Tsuneo; Ohji, Kenzo; Ono, Shusuke; Yamazaki, Osamu; Wasa, Kiyotaka (Mater. Res. Lab. , Matsushita Electr. Ind. Co., Osaka, Japan), Natl. Tech. Rep. ((Matsushita Electr. Ind. Co., Osaka) 1976, 22(6), 905-23 (Japan), highly oriented radio-frequency sputtered films of ZnO and Bi₁₂Pb0₁₉ were prepared. In "Optical and electronic properties of zinc oxide films prepared by spray pyrolysis." Major S.; Banerjee, A; Chopra, K. I. (Cent. Energy Stud., Indian Inst. Technol., New Delhi, 110016 India.) Thin Solid Films 1985, 125(0 2). 179-85 the optical properties of transparent conducting ZnO films prepared by spray pyrolysis were studied in the UV visible and IR regions.

One process undergoing development for applying a superconductor layer or material onto a copper wire, includes surrounding a copper wire with a yttrium-oxide and barium- carbonate powder pack. The powder is fired similar to other conventional methods of processing of bulk superconducting material.

During the process, the outer layer of the copper wire is oxidized producing a copper oxide layer around the wire. The yttrium and barium components react with this copper oxide by diffusion to produce a superconducting compound, a layer or an outer coating.

The results published to date showed a 5- to 10-micron layer (depending on firing time) of material in which all three of the constituent elements were present, as observed on the copper wire by a scanning electron microscope. Whether or not they were present consistently and continuously in the appropriate crystal from was not determined, but the Ener Dispersive Analysis indicated a correct element ratios.

It was also observed that the material could possibly b in patches or the crystals slightly removed from each other thus disabling a continuous circuit. SEM analysis revealed th porous nature of the ceramic material and the agglomerated grainy mix of the various phases within the material.

Disclosure of the Invention

A new process, e.g., a "non-line-of-sight" or "thre dimensional" process, useful for coating three dimensiona substrates would be advantageous. As used herein, a "non-line of-sight" or "three dimensional" process is a process whic coats surfaces of a substrate with transition metal oxide whic surfaces would not be directly exposed to transition meta oxide-forming compounds being deposited on the external surfac of the substrate during the first contacting step and/or t improve the processability to conductive and/or ferro magneti components and articles and/or for the type of substrate to b coated. In other words, a "three dimensional" process coats coatable substrate surfaces which are at least partially shielded by other portions of the substrate which are closer to the external surface of the substrate and/or which are further from the transition metal oxide forming source during processing, e.g., the internal and/or opposite side surfaces of a glass or ceramic particles such as fibers or spheres or flakes or other shapes or surfaces.

A new process for at least partially coating a three dimensional inorganic substrate having shielded surfaces with a transition metal electrically conductive or ferromagnetic oxide-forming material on at least a part of all three dimensions thereof and on at least a part of said shielded surfaces thereof has been discovered. In brief, the process comprises contacting the substrate with a transition metal oxide precursor, for example, stannous chloride, zinc chloride, cuprous chloride, ferric chloride in a vaporous form and/or in a liquid form and/or in a solid (e.g., powder) form, to form a transition metal oxide precursor-containing coating, fo example, a transition metal chloride-containing coating, on th substrate; preferably contacting the substrate with at leas one interacting component, i.e., a conductivity interactive o a ferromagnetic interacting component and contacting the coate substrate with an oxidizing agent to form a transition meta oxide-containing coating and recovering a coated substrate preferably a semi conductor ferromagnetic oxide-containin coated substrate more preferably an n type oxide sem conductor, more particularly a doped semi-conductor and/or sem conductor having a defect and/or non- stoichiometric structur which enhances conductivity. The contacting of the substrat with the transition metal oxide precursor and with th interacting component can occur together, i.e. , simultaneously, and/or in separate steps. The electrically conductive o ferromagnetic coated substrate is then recovered.

The process can provide coated substrates includin single and mixed oxides which have substantial and/o application designed electrical conductivity or ferromagnetic properties so as to be suitable for use as components in a wide variety of applications. Substantial coating uniformity, e.g., in the thickness of the transition metal oxide-containing coating and in the distribution of interacting component in the coating, is obtained. Further, the present transition metal oxide coated substrates in general have outstanding stability, e.g., in terms of electrical or magnetic properties and morphology and are thus useful in various applications.

Best Mode for Carrying Out the Invention The present coating process comprises contacting a substrate with a composition comprising a transition metal oxide precursor, such as transition metal chloride forming components, transition metal complexes and mixtures thereof, at conditions, preferably substantially non-deleterious oxidizing and/or hydrolyzing conditions, more preferably in a substantially inert environment or atmosphere, effective to form a transition metal oxide precursor-containing coating on the substrate, such as a stannous chloride, zinc chloride, cuprous chloride or ferric chloride containing coating, on least a portion of the substrate. The substrate is preferab also contacted with at least one conductivity or ferr magnetic interacting component, hereinafter referred to interacting component, such as at least one dopant compound, conditions, preferably at substantially non-deleteriou oxidizing and/or hydrolyzing conditions, more preferably in substantially inert atmosphere, effective to form a interacting component-containing coating, such as a dopan component-containing coating, on at least a portion of th substrate. The substrate, including one or more coating containing transition metal oxide precursor, and preferably a interacting component, for example a dopant component, i contacted with at least one oxidizing agent at condition effec- tive to convert the transition metal oxide precursor t transition metal oxide and form a transition metal oxide containing, preferably a binary or ternary transition meta oxide-containing, coating, preferably a semi conductor, supe conductor or ferromagnetic transition metal oxide-containin coating, on at least a portion of the substrate. By "non deleterious oxidation" is meant that the majority of th oxidation of transition metal oxide precursor, for exampl stannous chloride, zinc chloride, cuprous chloride and ferri chloride coated onto the substrate, takes place in th oxidizing agent contacting step of the process afte distribution and/or equilibration of the precursor, rather than in process step or steps conducted at non-deleterious oxidizin hydrolyzed conditions. The process as set forth below will be described in many instances with reference to stannous chloride, zinc chloride, cuprous chloride and ferric chloride which have been found to provide particularly outstanding process and product properties. However, it is to be understood that other suitable transition oxide precursors are included within the scope of the present invention. The interacting component-containing coating may be applied to the substrate before and/or after and/or during the time the substrate is coated with transition metal chloride and/or after contacting with the oxidized agent. In a particularly useful embodiment, the transition metal chlorid and the interacting component are both present in the sam composition used to contact the substrate so that th transition metal containing coating further contains th interacting component.

In another useful embodiment, the substrate with the transition metal chloride-containing coating and optimally the interacting component-containing coating is maintained at conditions preferably at substantially non-deleterious oxidizing and/or hydrolyzing conditions for example, conditions which reduce and/or minimize the formation of transition metal oxide on a relatively small portion of the substrate or off the substrate, for a period of time effective to do at least one of the following: (1) coat a larger portion of the substrate with a transition metal chloride containing coating; (2) distribute the transition metal chloride coating over the substrate; (3) make the transition metal chloride-containing coating more uniform in thickness; and (4) distribute the interacting component more uniformly in the transition metal chloride- containing coating. Such maintaining preferably occurs for a period of time in the range of about 0.05 or 0.1 minute to about 20 minutes in the presence of an inert gas an/or oxygen i.e. air, under non-deleterious oxidizing conditions. Such maintaining is preferably conducted at the same or a higher temperature relative to the temperature at which the substrate/transition metal chloride-containing composition contacting occurs. Such maintaining, in general, acts to make the coating more uniform and, thereby, for example, provides for beneficial electrical conductivity of ferromagnetic properties. The thickness of the transition metal oxide- containing coating can vary over a wide range and optimized for a given application and is generally in the range of from about 0.1 to about 100 microns or even from about 0.1 to about 50 microns, more preferably from about 0.1 micron to about 10 microns, still more preferably from about 0.25 micron to about 1.25 microns or from even about 0.2 to about 1 micron.

The transition metal which is contacted with the substrate is in a vaporous phase or state, or in a liquid phase or state, or in a solid state or phase (powder) at the time o the contacting. The composition which includes the transitio metal chloride preferably also includes the interactin component or components. This composition may also include on or more other materials, e.g., dopants, catalysts, grain growt inhibitors, solvents, etc., which do not substantiall adversely promote the premature hydrolysis and/or oxidation o the transition metal chloride and/or the interacting component and do not substantially adversely affect the properties of th final product, such as by leaving a detrimental residue in th final product prior to the formation of the transition meta oxide-containing coating. Thus, it has been found to b important, e.g., to obtaining a transition metal oxide coatin with good structural, mechanical and/or electronic and/or magnetic properties, that undue hydrolysis of the transition metal chloride and interacting component be avoided. This is contrary to certain of the prior art which actively utilized the simultaneous hydrolysis reaction as an approach to form the final coating. Examples of useful other materials include organic components such as acetonitrile, ethyl acetate, dimethyl sulfoxide, propylene carbonate and mixtures thereof; certain inorganic salts and mixtures thereof. These other materials, which are preferably substantially anhydrous, may often be considered as a carrier, e.g. , solvent, for the transition metal chloride and/or interacting component to be contacted with the substrate.

The transition metal oxide coatings are derived from transition metal precursors as set forth above which transition metal precursors contain transition elements of atomic numbers 21 - 31, 39 - 49 and 71 - 81, inclusive. Examples of transition metals are tin, copper, zinc, iron, chromium, tungsten, titanium, molybdenum and indium. The preferred transition elements are tin, copper, zinc, iron, chromium, tungsten, titanium, molybdenum, indium and mixtures. The particularly preferred transition metal elements are tin, zinc, iron, chromium, titanium and mixtures thereof.

As set forth above the transition metal oxide precursor is preferably selected from the group consisting of one or more transition metal chlorides, organic complexes, organic salts particularly organic complexes and salts which do not adversel oxidize and/or hydrolyze under the conditions of coating th substrate with the transition metal oxide precursor an mixtures thereof. Particularly preferred precursors ar transition metal chlorides and organic complexes, particularl di-ketone type complexes, i.e., acetylacetonate complexes. I is preferred that the precursors have a temperature rang between its melting point and boiling point, which allows fo effective maintaining and equilibrium of the precursor liqui coating as more specifically set forth above. For example stannous chloride is preferred over stannic chloride due to th wide temperature range from melting point to boiling point o stannous chloride. As set forth above, the preferred complexe are polyfunctional complexes, i.e., di-ketone complexes preferred organic complexes and salts are precursors which d not under go adverse rapid hydrolysis and/or oxidation and/o require undue pyrolyses of the organic carbon portion of th complex or salt and prior to and/or during the maintainin equilibrium step of the process of this invention and/or prio to the oxidation step for conversion to the transition meta oxide. In addition, such polyfunctional complexes, i.e., ketone complexes are preferred over organic acid and/o alcoholate transition metal salts. Typical examples of transition metal chloride precursor are stannous chloride, cuprous chloride, zinc chloride, ferri chloride, tungsten penta chloride, tungsten hexa ' chloride, molybdenum penta chloride, indium dichloride, indiu monochloride, chromium² chloride and titanium tetrachloride. Preferred transition metal complexes are polyfunctional keton complexes wherein such poly ketone functionality is capable o complexing with the transition metal. For example, acetylacetonate complexes, i.e., complexes of zinc, chromiu and the like. It has also been found that the substrate can first be contacted with a transition metal oxide precursor powder, particularly transition metal chloride powder, preferably with a film forming amount of such powder, followed by increasing the temperature of the powder to the liquidous point of th powder on the substrate and maintaining the coated substrat for a period of time at conditions including the increase temperature effective to do at least one of the following: (1 coat a larger portion of the substrate with the transitio metal oxide precursor-containing coating; (2) distribute th coating over the substrate; and (3) make the coating mor uniform in thickness. Preferably, this step provides for th equilibration of the coating on the substrate. The siz distribution of the powder, for example, transition meta chloride powder, and the amount of such powder applied to th substrate are preferably chosen so as to distribute the coatin over substantially the entire substrate.

The transition metal oxide precursor powder can be applied to the substrate as a powder, particularly in the range of about 5 or about 10 to about 125 microns in average particle size the size in part being a function of the particle size, i.e. smaller particles generally require smaller size powders. The powder is preferably applied as a charged fluidized powder, in particular having a charge opposite that of the substrate or at a temperature where the powder contacts and adheres to the substrate. In carrying out the powder coating, the coating system can be, for example, one or more electrostatic fluidized beds, spray systems having a fluidized chamber, and other means for applying powder, preferably in a film forming amount. The amount of powder used is generally based on the thickness of the desired coating and incidental losses that may occur during processing. The powder process together with conversion to a transition metal oxide-containing coating can be repeated to achieve desired coating properties, such as desired gradient conductivities.

Typically, the fluidizing gaseous medium is selected to be compatible with the transition metal oxide precursor powder, i.e., to not substantially adversely affect the formation of a coating on the substrate during melting and ultimate conversion to a transition metal oxide-containing film.

Generally, gases such as air, nitrogen, argon, helium and the like, can be used, with air being a gas of choice, where no substantial adverse prehydrolysis or oxidation reaction of th powder precursor takes place prior to the oxidation-reaction t the transition metal oxide coating as previously discusse under equilibration and maintaining. The gas flow rate is typically selected to obtain fluidization and charge transfer to the powder. Fine powders require less gas flow for equivalent deposition. It has been found that small amounts of water vapor enhance charge transfer. The temperature for contacting the substrate with a powder precursor is generally in the range of about 0° C to about 100° C or higher, more preferably about 20° C to about 40° C, and still more preferably about ambient temperature. The substrate however, can be at a temperatures the same as, higher or substantially higher than the powder. The time for contacting the substrate with precursor powder is generally a function of the substrate bulk density, thickness, powder size and gas flow rate. The particular coating means is selected in part according to the above criteria, particularly the geometry of the substrate. For example, particles, spheres, flakes, short fibers and other similar substrate, can be coated directly in a fluidized bed themselves with such substrates being in a fluidized motion or state. For fabrics, single fibers, rovings and tows a preferred method is to transport the fabric and/or roving directly through a fluidized bed for powder contacting. In the case of rovings and tows, a fiber spreader can be used which exposes the filaments within the fiber bundle to the powder. The powder coating can be adjusted such that all sides of the substrate fabric, roving and the like are contacted with powder. Typical contacting time can vary from seconds to minutes, preferably in the range of about 1 second to about 120 seconds, more preferably about 2 seconds to about 30 seconds. Typical transition metal oxide precursor powders are those that are powders at powder/substrate contacting conditions and which are liquidous at the maintaining conditions, preferably equilibration conditions, of the present process. It is preferred that the powder on melting substantially wets the surface of the substrate, preferably having a low contact angle formed by the liquid precursor contact with the substrate and has a relatively low viscosi and low vapor pressure at the temperature conditions of melti and maintaining, preferably melting within the range of abo 100° C to about 650° C or higher. For tin oxide precurs powder it is preferred that melting is within the range of fr about 100° to about 450°, more preferably about 250° C to abo 400° C. Typical powder transition metal oxide precursors a stannous chloride, low molecular weight organic salts complexes of tin, particularly low molecular weight organ salts and complexes such as stannous acetate a acetylacetonate complexes of tin.

An additional component powder, such as a dopant-formi powder, can be combined with the transition metal oxi precursor powder. A particularly preferred dopant-formin powder for tin oxide is stannous fluoride. Further, a additional component, such as a dopant, for example a fluorin or fluoride component, indium, or antimony for tin oxid coatings can be incorporated into the coating during th maintaining step, for example hydrogen fluoride gas as a sourc of fluoride. A combination of the two methods can also be use for additional component incorporation.

Typical zinc oxide precursor powders are those that ar powders at powder/substrate contacting conditions and which ar liquidous at the maintaining conditions, preferabl equilibration conditions, of the present process, preferabl melting within the range of about 100° C to about 450° C, o higher, more preferably about 250° C to about 400° C. Typica powder zinc oxide precursors are zinc chloride, low molecula weight organic salts or complexes of zinc, particularly lo molecular weight organic salts and complexes such as zin acetate and acetylacetonate complexes of zinc.

An additional component powder, such as a dopant-formin powder, can be combined with the zinc oxide precursor powder. Particularly preferred dopant-forming powders are aluminum an chromium acetylacetonate, benzylate and methyl substitute benzylate, cobalt II chloride, gallium dichloride, indium mono and dichloride, stannous chloride and germanium monoxide. Further, an additional component, such as a dopant, for exampl a chloride component, aluminum or titanium, can be incorporate into the coating during the maintaining step, for example aluminum chloride, titanium tetrachloride gas as a source of the metal dopant, preferably in a hydrogen chloride atmosphere. A combination of the two methods can also be used for additional component incorporation.

Typical copper oxide precursor powders are those that are powders at powder/substrate contacting conditions and which are liquidous at the maintaining conditions, preferably melting within the range of about 100° C to about 650° C, more preferably about 435° C to about 630° C. Typical powder copper oxide precursors are cuprous chloride, cuprous oxide low molecular weight organic salts or complexes of copper, particu- larly low molecular weight organic salts and complexes including poly functional/carboxyl, hydroxyl and ketone such as cuprous acetate and acetylacetonate complexes of copper.

An additional component powder, such as the conductivity forming additional powders, can be combined with the copper oxide precursor powder. The particularly preferred additional powders are yttrium chloride and/or oxide, barium carbonate and/or oxide or peroxide. Further, additional components can be incorporated into the coating during the maintaining step, for example a gas as a source of such additional component. A combination of the two methods can also be used for additional component incorporation.

As set forth above, the copper oxide precursor powders and additional component conductivity interacting component can produce a film forming amount precursor component on the substrate, particularly distribution of the film over a substantial part of said substrate, followed by oxidation. In addition to the precursor components set forth above, nitrates, sulfates and their hydrates, as well as the hydrates of for example chloride, can be selected and used within the processing requirements for producing such conductive films.

Typical iron oxide precursor powders are those that are powders at powder/substrate contacting conditions and which are liquidous at the maintaining conditions of the present process. ^'preferably melting within the range of about 300° C to about 450° C, or higher, more preferably about 350° C to about 300° C. Typical powder iron oxide precursors are ferric chloride, low molecular weight complexes of iron, such as poly functionality and complexes with carboxylic, ketone and hydroxyl functionality, such as acetylacetonate complexes of iron.

An additional component powder, such as a dopant-forming powder, can be combined with the iron oxide precursor powder. Particularly preferred interacting-forming powders are compounds of nickel, zinc, manganese, yttrium, the rare earths, barium, calcium and silica. Further, an additional component, such as an interacting component, for example a chloride hydrate and/or nitrate hydrate and/or a di-ketone complex can be incorporated into the coating during the maintaining step, for example, zinc acetylacetonate as a source of the metal interacting compound, preferably in a hydrogen chloride atmosphere. A combination of the two methods can also be used for additional component incorporation.

The powder transition metal oxide precursor on melting is maintained and/or equilibrated as set forth above. In addition, temperatures can be adjusted and/or a component introduced into the melting/maintaining step which can aid in altering the precursor for enhanced conversion to transition metal oxide. For example, gaseous hydrogen chloride can be introduced to form partial or total halide salts and/or the temperature can be adjusted to enhance decomposition of, for example, transition metal organic salts and/or complexes to more readily oxidizable transition metal compounds. The interacting component can also be present in an oxide or precursor form in the melt as a dispersed preferably as a finely dispersed solid. The oxide can be incorporated advantageously as part of the powder coating of the substrate material.

A fluidizable coated substrate, such as substrates coated directly in a fluid bed of powder, can be subjected to conditions which allow liquidous formation by the transition metal oxide precursor and coating of the substrate. A particularly preferred process uses a film forming amount of the transition metal oxide precursor which allows for coating during the liquidous step of the process, and which substantially reduces detrimental substrate agglomeration. The conditions are adjusted or controlled to allow substantially free substrate fluidization and transport under the conditions of temperature and bed density, such as dense bed density to lean bed density. The coated substrate can be further transported to the oxidation step for conversion to transition metal oxide or converted directly to transition metal oxide in the same reactor/processing system or such conversion can take place in the same reactor under substrate fluidizing conditions. In the former, liquidous coated substrate is transported as a dense bed to a fluidized oxidation zone, such zone being a fluidized zone preferably producing a conversion to transition metal oxide on the substrate of at least about 80% by weight.

The transition metal chloride and/or interacting component to be contacted with the substrate may be present in a molten state. For example, a melt containing molten transition metal chloride and/or interacting component, i.e. chloride or fluoride salt, may be used. The molten composition may include one or more other materials, having properties as noted above, to produce a mixture, e.g., a eutectic mixture, having a reduced melting point and/or boiling point. The use of molten transition metal chloride and/or interacting component provides advantageous substrate coating while reducing the handling and disposal problems caused by a solvent. In addition, the substrate is very effectively and efficiently coated so that coating material losses are reduced. The transition metal chloride and/or interacting component to be contacted with the substrate may be present in a vaporous and/or atomized state. As used in this context, the term "vaporous state" refers to both a substantially gaseous state and a state in which the transition metal chloride and/or interacting component are present as drops or droplets and/or solid dispersion such as colloidal dispersion in a carrier gas, i.e., an atomized state. Liquid state transition metal chloride and/or interacting component may be utilized t generate such vaporous state compositions.

In addition to the other materials, as noted above, th composition containing transition metal chloride and/or th dopant-forming component may also include one or more grai growth inhibitor components. Such inhibitor component o components are present in an amount effective to inhibit grai growth in the transition metal oxide-containing coating Reducing grain growth leads to beneficial coating properties e.g., higher electrical conductivity, more uniform morphology and/or greater overall stability. Among useful grain growt inhibitor components are components which include at least on metal, in particular potassium, calcium, magnesium, silicon an mixtures thereof. Of course, such grain growth inhibito components should have no substantial detrimental effect on th final product.

The interacting component may be deposited on th substrate separately from the transition metal chloride e.g., before and/or during and/or after the transition metal chloride/substrate contacting and after contacting with the oxidizing agent, such as by dopant implantation. If the interacting component is deposited on the substrate separately from the transition metal chloride, it is generally preferred that the interacting component, be deposited after the transition metal chloride, such as to form soluble and/or eutectic mixtures and/or dispersions.

Any suitable interacting component may be employed in the present process. Such interacting component should provide sufficient interacting component so that the final transition metal oxide coating has the desired properties, e.g., electronic conductivity, stability, magnetic properties, etc. Care should be exercised in choosing the interacting component or components for use. For example, the interacting component should be sufficiently compatible with, for example, the transition metal chloride so that the desired transition metal oxide coating can be formed. Interacting components which have excessively high boiling points and/or are excessively volatile (relative to transition metal chloride) , at the conditions employed in the present process, are not preferred since, for example, the final coating may not be sufficiently developed with the desired properties and/or a relatively large amount of the interacting component or components may be lost during processing. It may be useful to include one or more property altering components, e.g., boiling point depressants, in the composition containing the dopant-forming component to be contacted with the substrate. Such property altering component or components are included in an amount effective to alter one or more properties, e.g., boiling point, of the interacting component, e.g., to improve the compatibility or reduce the incompatibility between the interacting component and transition metal chloride.

Particularly useful dopants for use in the tin oxide products and process of this invention are anion dopants, particularly fluorine components selected from stannous fluoride, stannic fluoride, hydrogen fluoride, ammonium fluoride, ammonium bi-fluoride and mixtures thereof. When stannous fluoride is used as a fluorine component, it is preferred to use one or more boiling point depressants to reduce the apparent boiling point of the stannous fluoride, in particular to at least about 850°C or less. The preferred dopants are those that provide for optimum dopant incorporation while minimizing dopant precursor losses, particularly under the preferred process conditions as set forth therein. In addition oxides or sub-oxides can also be used, including where dopant incorporation is accomplished during the oxidation sintering contacting step.

The use of a fluorine or fluoride dopant is an important feature of certain aspects of the present invention. First, it has been found that fluorine dopants can be effectively and efficiently incorporated into the tin oxide-containing coating. In addition, such fluorine dopants act to provide tin oxide contain-ing coatings with good electronic properties referred to above, morphology and stability. This is in contrast to certain of the prior art which found antimony dopants to be ineffective to improve the electronic properties of tin oxide coatings in specific applications. Particularly useful dopant components for use in the zi oxide products and process of the present invention a selected from aluminum, cobalt, gallium, titanium, indium, t and germanium, particularly oxide forming dopant components, well as zinc metal forming compounds and/or the use of suc process condition which form dopant concentrations of zin metal. Preferred dopant oxide precursors are set for above an include the halide, preferably the chlorides, organi complexes, such as low molecular weight organic acid salts complexes, such as low molecular weight, ketone components preferably 2 , 4, dienes, benzylates and the like. Th preferred dopants are those that provide for optimum dopan oxide incorporation while minimizing dopant precursor losses particularly under the preferred process condition as set fort herein. Oxides or suboxides can also be used where dopan incorporation is accomplished during the oxidation sinterin contacting step.

The use of a dopant is an important feature of certai aspects of the present invention. First, it has been foun that such dopants, particularly alumina can be effectively an efficiently incorporated into the zinc oxide-containin coating. In addition, such dopants act to provide zinc oxide- containing coatings with good electronic properties referred to above, morphology and stability. Any suitable conductivity compatible and/or enhancing component may be employed in the copper oxide product and processes of this invention. Such conductivity interacting component should provide sufficient stoichio etry so that the final copper oxide coating has the desired properties, e.g., electronic conductivity, stability, etc. Chloride, nitrate, sulfate, organic complexes as set forth above and their hydrate components are particularly useful additional components with oxide, peroxide and carbonates being also useful. Care should be exercised in choosing the additional component or components for use. For example, the components should be sufficiently compatible with the cuprous chloride so that the desired conductive copper oxide coating can be formed. The use of an additional component is an important feature of certain aspects of the present invention. First, it has been found that such components can be effectively and efficiently incorporated into the copper oxide-containing coating. In addition, such additional components act to provide copper oxide-containing coatings with excellent electronic properties referred to above, morphology and stability. Any suitable interacting-forming component may be employed in the iron oxide products and processes of this invention. Such interacting- forming component should provide sufficient concentration so that the final iron oxide coating has the desired properties, e.g., magnetic, high permeability, stability, for example, nickel, manganese or zinc components. Preferred iron component oxide precursors are set for above and include the halide, preferably the chlorides, organic complexes, such as low molecular poly functional organic acids, complexes, such as low molecular weight, ketone components, preferably 2, 4, ketones, benzylates and the like. The preferred interacting components are those that provide «for optimum oxide incorporation while minimizing dopant precursor losses, particularly under the preferred process condition as set forth herein. Oxides or suboxides can also be used where dopant incorporation is accomplished during the oxidation sintering contacting step.

The use of an interacting component is an important feature of certain aspects of the present invention. First, it has been found that interacting components can be effectively and efficiently incorporated into the iron oxide-containing coating. In addition, such interacting components act to provide iron oxide-containing coatings with good magnetic properties referred to above, morphology and stability. The liquid, e.g., molten, composition which includes transition metal chloride may, and preferably does, also include the interacting component. In this embodiment, the interacting component or components are preferably soluble and/or dispersed homogeneously and/or atomized in the composition. Vaporous mixtures of transition metal chloride and interacting components may also be used. Such compositions are particularly effective since the amount of interacting component in^' the final transition metal oxide coating can be controlled by controlling the make-up of the composition. I addition, both the transition metal chloride and interactin component are deposited on the substrate in one step. Moreover, if stannous fluoride and/or stannic fluoride are used, such fluorine components provide the dopant and are converted to tin oxide during the oxidizing agent/substrate contacting step. This enhances the overall utilization of the coating components in the present process. Particularly useful compositions comprise about 50% to about 98%, more preferably about 70% to about 95%, by weight of stannous chloride and about 2% to about 50%, more preferably about 5% to about 30%, by weight of fluorine component, in particular stannous fluoride.

In addition, if zinc chlorides are used, such chloride components provide the dopant and are converted to oxides during the oxidizing agent/substrate contacting step. This enhances the overall utilization of the coating components in the present process. Particularly useful final zinc oxide compositions comprise about 0.1% to about 5%, more preferably about 0.5% to about 3%, by weight of dopant oxide.

In addition, if cuprous chloride and yttrium chloride, and a barium oxide precursor (dispersed) are used, such components provide the conductivity stoichiometry and are converted to copper oxide during the oxidizing agent/substrate contacting step. This enhances the overall utilization of the coating components in the present process. Particularly useful compositions produce a yttrium to barium to copper oxide ratio of 1,2,3 or 1,2,4.

As described herein, a preferred class of superconductors are the 1, 2, 3 and 1, 2, 4 superconductors of yttrium, barium and copper. In addition, thallium, barium, calcium and copper oxide in an atomic weight ratio of about 2, 2, 2, 3 are also preferred. Bismuth based copper oxide conductors are further examples of conductors within the scope of this invention. The films prepared by the process of this invention enhance the current carrying capability of the conductors, can reduce grain boundary current carry effects or provide improved control of oxidation and/or annealing conditions and uniformity, including the requisite atomic weight stoichiometry.

In addition, if chlorides or organic precursors of iron are used, such precursor components are converted to oxides during the oxidizing agent/substrate contacting step. This enhances the overall utilization of the coating components in the present process.

In one embodiment, a vaporous transition metal chloride composition is utilized to contact the substrate, and the composition is at a higher temperature than is the substrate. The make-up of the vaporous transition metal chloride- containing composition is such that transition metal chloride condensation occurs on the cooler substrate. If the interacting component is present in the composition, it is preferred that such interacting component also condense on the substrate. The amount of condensation can be controlled by controlling the chemical make-up of the vaporous composition and the temperature differential between the composition and the substrate. This "condensation" approach very effectively coats the substrate to the desired coating thickness without requiring that the substrate be subjected to numerous individual or separate contactings with the vaporous transition metal chloride-containing composition. As noted above, previous vapor phase coating methods have often been handicapped in requiring that the substrate be repeatedly recontacted in order to get the desired coating thickness. The present "condensation" embodiment reduces or eliminates this problem.

The substrate including the transition metal chloride- containing coating and the interacting component-containing coating is contacted with an oxidizing agent at conditions effective to convert transition metal chloride to transition metal oxide, and form a conductive or ferro magnetic tin oxide coating on at least a portion of the substrate. Water, e.g., in the form of a controlled amount of humidity, is preferably present during the coated substrate/oxidizing agent contacting. This is in contrast with certain prior transition metal oxide coating methods which are conducted under anhydrous conditions. The presence of water during this contacting has been found to provide a doped tin oxide coating having excellent electrical conductivity properties.

Any suitable oxidizing agent may be employed, provided that such agent functions as described herein. Preferably, the oxidizing agent (or mixtures of such agents) is substantially gaseous at the coated substrate/oxidizing agent contacting conditions. The oxidizing agent preferably includes reducible oxygen, i.e., oxygen which is reduced in oxidation state as a result of the coated substrate/oxidizing agent contacting. More preferably, the oxidizing agent comprises molecular oxygen, either alone or as a component of a gaseous mixture, e.g. , air.

The substrate may be composed of any suitable inorganic material and may be in any suitable form. Preferably, the substrate is such so as to minimize or substantially eliminate deleterious substrate, coating reactions and/or the migration of ions and other species, if any, from the substrate to the transition metal oxide-containing coating which are deleterious to the functioning or performance of the coated substrate in a particular application. However, controlled substrate reaction which provides the requisite stoichiometry can be used and such process is within the scope of this invention. In addition, it can be precoated to minimize migration, for example an alumina and/or a silica precoat and/or to improve wetability and uniform distribution of the coating materials on the substrate. Further, the transition metal oxide component, article can be further coated with a barrier film, organic and/or inorganic to minimize reaction of components such as corrosive gaseous materials with the final transition metal oxide component/article. In order to provide for controlled electrical conductivity in the conductive transition metal oxide coating, it is preferred that the substrate be substantially non-electronically conductive and/or non- deleterious reactive and/or substantial non-magnetic when the coated substrate is to be used as a component of an electric energy storage battery, acoustic device and/or magnetic device. The substrate is inorganic, for example metal, glass and/or ceramic and/or carbon. Examples of three dimensiona substrates which can be coated using the present proces include spheres, such as having a diameter of from about micron to about 500 microns more preferably from about 1 microns to about 150 microns, extrudates, flakes, singl fibers, fiber rovings, chopped fibers, fiber mats, aggregates, porous substrates, stars, irregularly shaped particles, e.g., catalyst supports, rings, saddles, multi-channel monolith tubes, conduits and the like. The coated particles including spherical particles ar particularly useful in a number of applications, particularl lead acid batteries, including conductivity additives fo positive active material, catalysts, resistance heatin elements, electrostatic dissipation elements, electromagnetic interference shielding elements, electrostatic bleed elements, protective coatings, field dependent fluids and the like. In practice spherical particles for use in applications in general have a roundness associated with such particles, generally greater than about 70% still more preferably, greater than about 85% and still more preferably, greater than about 95%. The spherical products offer particular advantages in many of such applications disclosed herein, includ- ing enhanced dispersion and rheology, particularly in various compositions such as polymer compositions, coating compositions, various other liquid and solid type compositions and systems for producing various products such as coatings and polymer composites.

A particularly unique embodiment of the present transition metal oxide coated particles is the ability to design a particular density for a substrate through the use of one or more open or closed cells, including micro and macro pores particularly, closed cell voids in spheres which spheres are hereinafter referred to as hollow spheres. Thus such densities can be designed to be compatible and synergistic with other components used in a given application, particularly optimized for compatibility in liquid systems such as polymer coating compositions as set forth above. The average particle density can vary over a wide range such as densities of from about 0.1 g/cc to about 2.00 g/cc, more preferably from abouv. 0.13 g/cc to about 1.5 g/cc, and still more preferably from about 0.15 g/cc to about 0.80 g/cc.

As set forth above, spheres can be inorganic for example, carbon and/or an inorganic oxide. Typical examples of inorganic oxides which are useful as substrates include for example, substrates containing one or more alumino silicate, silica, sodium borosilicate, insoluble glass, soda lime glass, soda lime borosilicate glass, silica alumina, as well as such glasses and ceramics which are modified with, for example, another oxide such as titanium dioxide and/or small amounts of iron oxide.

A particularly unique coated three-dimensional substrate is a flake particle, such as having a diameter of from about 0.1 micron to about 100 microns more preferably from about 0.1 microns to about 30 microns, and still more preferably from about 0.1 microns to about 10 microns, particularly wherein the aspect ratio, i.e, the average particle length divided by the thickness of the particle is from about five to one to about 2,000 to 1, more preferably from about 20 to 1 to about 2,000 to 1 and still more preferably, from about 50 to 1 to about 1,000 to 1. Generally, the platelets will have a thickness varying from about 0.1 microns to about 10 microns, more preferably from about 0.1 micron to about 6 microns, more preferably from about 0.1 microns to about 10 microns, more preferably from about 0.l micron to about 6 microns. The average length, i.e., the average of the average length plus average width of the platelet, i.e., flake, will generally be within the aspect ratios as set forth above for a given thickness. Thus for example the average length as defined above can from about 5 microns to about 3,500 microns, more typically from about 40 microns to about 3,200 microns. In general, the average length can vary according to the type of substrate and the method used to produce the platelet material. For example, C glass in general has an average length which can vary from about 200 microns up to about 3,200 microns, typical thicknesses of from about 1.5 to about 7 microns. Other platelet materials for example, hydrous aluminum silicate mica, in general can vary in length from about 5 to about 250 micron at typical thicknesses or from about 0.1 to about 4.0 microns, preferably within the aspect ratios set forth above. I practice the platelet particles which are preferred for use i such application sin general have an average length less than about 400m microns and an average thickness of from about 0.1 to about 6 microns. Ceramic and metal fibers, especially continuous fibers, are particularly useful substrates when the copper oxide coated substrate is to be used as a superconductor.

The substrate for use in lead-acid batteries is acid resistant. That is, the substrate exhibits some resistance to corrosion, erosion and/or other forms of deterioration at the conditions present, e.g., at or near the positive plate, or positive side of the bipolar plates, in a lead-acid battery. The conditions at which each of the steps of the present process occur are effective to obtain the desired result from each such step and to provide a substrate coated with a transition metal oxide-containing coating. For example, the substrate/ stannous chloride contacting and the substrate/dopant-forming component contacting preferably occur at a temperature in the range of about 250°C to about 375°C, more preferably about 275°C to about 350°C. The amount of time during which stannous chloride and/or dopant-forming component is being deposited on the substrate depends on a number of factors, for example, the desired thickness of the transition metal oxide-containing coating, the amounts of stannous chloride and dopant-forming component available for substrate contacting, the method by which the stannous chloride and dopant-forming component are contacted with the substrate and the like. Such amount of time for transition metal halides preferably in the range of about 0.5 minutes to about 20 minutes, more preferably about 1 minute to about 10 minutes. If the coated substrate is maintained in a substantially non-deleterious oxidizing environment, as previously set forth. For tin oxide coatings it is preferred that such maintaining occur at a temperature in the range of about 275°C to about 375°C, more preferably about 300°C to about 350°C for a period of time in the range of about 0.1 minutes to about 20 minutes more preferably about 1 minute to about 10 minutes. The coate substrate/oxidizing agent contacting preferably occurs at temperature in the range of about 350°C to about 600°C, mor preferably about 400°C to about 550°C, for a period of time i the range of about 0.1 minutes to about 10 minutes. particular advantage of the process of this invention is th temperatures used for oxidation particularly tin oxide hav been found to be lower, in certain cases, significantly lower i.e., 50 to 100°C than the temperatures required for spra pyrolysis.

For substrate/zinc chloride contacting, including fo example the substrate/dopant-forming component, contactin preferably occurs at a temperature in the range of about 290° to about 600°C, more preferably about 310°C to about 400°C. The amount of time during which zinc chloride and/or dopant-formin component is being deposited on the substrate depends on a number of factors, for example, the desired thickness of the zinc oxide-containing coating, the amounts of zinc chloride and dopant-forming component available for substrate contacting, the method by which the zinc chloride and dopant-forming component are contacted with the substrate and the like.

If the zinc chloride coated substrate is maintained in a substantially non-deleterious oxidizing environment, it is preferred that such maintaining occur at a temperature in the range of about 290°C to about 600°C, more preferably about 310°C to about 400°C for a period of time in the range of about 0.05 or 0.1 minutes to about 20 minutes, more preferably about 0.5 or 1 minute to about 10 minutes. The coated substrate/oxidizing agent contacting preferably occurs at a temperature in the range of about 550°C to about 700°C, more preferably about 600°C to about 675°C, for a period of time in the range of about 0.05 or 0.1 minutes to about 10 minutes. Additional contacting at a higher temperature up to about 850°C for a period of up to about 0.5 to about 2 hours can be used to fully develop the electrical conductivity properties. A particular advantage of the process of this invention is that the temperatures used for oxidation have been found to be lower, in certain cases, significantly lower, i.e., 50 to 200° than the temperatures required for spray hydrolysis. This i very significant and unexpected, provides for proces efficiencies and reduces, and in some cases substantiall eliminates, migration of deleterious elements from th substrate to the zinc oxide layer. Excessive ion migration, e.g., from the substrate, can reduce electronic conductivit depending on the substrate and processing condition. I addition, the oxidizing and or sintering steps can be combined with a carbon and/or sulfur source, such as to provide the desired oxides for developing enhanced conduction.

For the substrate/cuprous chloride contacting, for example in the presence of the substrate/additional component, contacting preferably occur at a temperature in the range of about 435°C to about 630°C, more preferably about 450°C to about 500°C. The amount of time during which cuprous chloride and/or dopant-forming component is being deposited on the substrate depends on a number of factors, for example, the desired thickness of the copper oxide-containing coating, the amounts of cuprous chloride and additional components available for substrate contacting, the method by which the cuprous chloride and additional components are contacted with the substrate and the like.

If the coated substrate is maintained in a substantially non-deleterious oxidizing environment, as previously set forth it is preferred that such maintaining occur at a temperature in the range of about 435°C to about 630°C, more preferably about 450°C to about 500°C for a period of time in the range of about 0.1 minutes to about 20 minutes, more preferably about 1 minute to about 10 minutes. The coated substrate/oxidizing agent contacting preferably occurs at a temperature in the range of about 500°C to about 900°C, more preferably about 700°C to about 850°C, for a period of time in the range of about 1 minute or up to about 4 hours.^' Additional contacting, i.e. annealing, of from about 450°C up to about 650°C can be used to develop optimum conductor properties. A particular advantage of the process of this invention is that the temperatures used for oxidation have been found to be lower, in certain cases, significantly lower, i.e., 50 to 100°C or even up to 200°C than the temperatures required for conventional sintering. This is very significant and unexpected, provides for process efficiencies and reduces, and in some cases substantially eliminates, deleterious reactions and/or migration of deleterious elements from the substrate to the copper oxide layer. Excessive reaction and/or migration, e.g., from or by the substrate, can reduce electronic conductivity depending on the substrate processing conditions. In addition, the oxidizing and/or sintering steps can be combined with a staged oxygen annealing step to develop optimum properties for example low to high or high to low concentrations of oxygen.

For the substrate/iron chloride precursor contacting for example, in the presence of the substrate/interacting forming component, contacting preferably occurs at a temperature in the range of about 30°C to about 450°C, more preferably about 35°C to about 300°C. The amount of time during which iron chloride precursor and/or interacting-for ing component is being deposited on the substrate depends on a number of factors, for example, the desired thickness of the iron oxide-containing coating, the amounts of iron chloride precursor and interacting-forming component available for substrate contacting, the method by which the iron chloride and dopant- forming component are contacted with the substrate and the like.

If the coated substrate is maintained in a substantially non-deleterious oxidizing environment, it is preferred that such maintaining occur at a temperature in the range of about 50°C to about 450°C, more preferably about 100°C to about 300°C for a period of time in the range of about 100°C to about 300 °C for a period of time in the range of about 0.05 or 0.1 minutes to about 20 minutes, more preferably about 0.5 or 1 minute to about 10 minutes. The coated substrate /oxidizing agent contacting preferably occurs at a temperature in the range of about 60°C to about 1000°C, more preferably about 750°C to about 900°C, for a period of time in the range of about 0.05 or 0.1 minutes to about 10 minutes. Additional contacting at a higher temperature up to about 850°C for a period of up about 0.5 to about 2 hours can be used to fully develop t electrical conductivity properties. A particular advantage o the process of this invention is that the temperatures used fo oxidation have been found to be lower, in certain cases significantly lower, i.e., 50 to 200°C than the temperature required for spray hydrolysis. This is very significant an unexpected, provides for process efficiencies and reduces, an in some cases substantially eliminates, migration o deleterious elements from the substrate to the iron oxid layer. Excessive ion migration, e.g., from the substrate, ca reduce permeability depending on the substrate and processin condition. In addition, the oxidizing and or sintering step can be staged with successive reductions in the oxygen conten of the gas and/or with a carbon source, to provide the desire oxygen content for developing enhanced magnetic properties.

Ferrite is a generic term describing a class of magneti oxide compounds that contain iron oxide as a major component

There are several crystal structure classes of compound broadly defined as ferrites, such as spinel, magnetoplumbite garnet, and perovskite structures.

Although there are many characterizations specific to given application, one property is shared by all material designed as ferrites, namely the existence of a spontaneou magnetization (a magnetic induction in the absence of a external magnetic field) .

Any suitable matrix material or materials may be used i a composite with the transition metal oxide coated substrate. Preferably, the matrix material comprises a polymeric material, e.g., one or more synthetic polymers, more preferably a organic polymeric material. The polymeric material may b either a thermoplastic material or a thermoset material. Amon the thermoplastics useful in the present invention are th polyolefins, such as polyethylene, polypropylene, polymethylpentene and mixtures thereof; and poly viny polymers, such as polystyrene, polyvinylidene difluoride, combinations of polyphenylene oxide and polystyrene, an mixtures thereof. Among the thermoset polymers useful in the present invention are epoxies, phenol-formaldehyde polymers polyesters, polyvinyl esters, polyurethanes, melamine- formaldehyde polymers, and urea-formaldehyde polymers.

In yet another embodiment, a coated substrate including transition metal oxide, preferably electronically conductive transition metal oxide, and at least one additional catalyst component in an amount effective to promote a chemical reaction is formed. Preferably, the additional catalyst component is a metal and/or a component of a metal effective to promote the chemical reaction. A particularly useful class of chemical reactions are those involving chemical oxidation or reduction. For example, an especially useful and novel chemical reduction includes the chemical reduction of nitrogen oxides, to minimize air pollution, with a reducing gas such as carbon monoxide, hydrogen and mixtures thereof. A particularly useful chemical oxidation application is a combustion, particularly catalytic combustion, wherein the oxidizable compounds, i.e., carbon monoxide and hydrocarbons are combusted to carbon dioxide and water. For example, catalytic converters are used for the control of exhaust gases from internal combustion engines and are used to reduce carbon monoxide and hydrocarbons from such engines. Of course, other chemical reactions, e.g., hydrocarbon reforming, dehydrogenation, such as alkylaromatics to olefins, olefins to dienes, alcohols to ketones hydrodecycliza- tion, isomerization, ammoxidation, such as with olefins, aldol condensations using aldehydes and carboxylic acids and the like, may be promoted using the present catalyst component, transition metal oxide-containing coated substrates. The transition metal oxide-containing coated substrates of the present invention may be employed alone or as a catalyst and/or support in a sensor, in particular gas sensors.

Any suitable catalyst component (or sensing component) may be employed, provided that it functions as described herein. Among the useful metal catalytic components and metal sensing components are those selected from components of the tins, the rare earth metals, certain other catalytic components and mixtures thereof, in particular catalysts containing gold, silver, copper, vanadium, chromium, cobalt molybdenum, tungsten, zinc, indium, the platinum group metals, i.e. platinum, palladium and rhodium, iron, nickel, manganese cesium, titanium, etc. Although metal containing compounds ma be employed, it is preferred that the metal catalyst componen (and/or metal sensing component) included with the coate substrate comprise elemental metal and/or metal in one or mor active oxidized forms, for example, Cr₂0₃, Ag₂0, etc.

The preferred support materials include a wide variety o materials used to support catalytic species, particularl porous refractory inorganic oxides. These supports include for example, alumina, silica, zirconia, magnesia, boria, phosphate, titania, ceria, thoria and the like, as well a multi-oxide type supports such as alumina-phosphorous oxide, silica alumina, zeolite modified inorganic oxides, e.g., silic alumina, and the like. As set forth above, support material can be in many forms and shapes, especially porous shapes whic are not flat surfaces, i.e., non line-of-site materials, including rings, saddles, stars, etc.. A particularly usefu catalyst support is a multi-channel monolith such as one mad from cordierite which has been coated with alumina. Th catalyst materials can be used as is or further processed suc as by sintering of powered catalyst materials into larger aggregates. The aggregates can incorporate other powders, for example, other oxides, to form the aggregates. A particularly unique property of the ferro magnetic catalysts of this invention is the ability to be able to separate and recover catalysts from solution and/or other non¬ magnetic or low permeability solids by magnetic separation. This is particularly advantageous in slurry catalysts, such as in liquid systems, such as hydrocarbon and/or aqueous and/or combination systems. This property allows separation including separation from other non-magnetic solids and separate catalysts regeneration if required.

Another unique property is the ability to heat the electrically conductive and/or ferro magnetic catalyst by induction heating as more fully described below. This property allows for far superior temperature control and thermal efficiencies. In addition, the ability to vary coating thickness an substrate composition allows designing catalyst for a give density, a feature important in gravity separation processes. The transition metal oxide/substrate combinations, e.g., the transition metal oxide coated substrates, of the present invention are useful in other applications as well. Among these other applications are included porous membranes, resistance heating elements, electrostatic dissipation elements, electromagnetic interference shielding elements, protective coatings, field dependent fluids and the like.

In one embodiment, a porous membrane is provided which comprises a porous substrate, preferably an inorganic substrate, and a transition metal oxide-containing material in contact with at least a portion of the porous substrate. In another embodiment, the porous membrane comprises a porous organic matrix material, e.g., a porous polymeric matrix material, and a transition metal oxide-containing material in contact with at least a portion of the porous organic matrix material. With the organic matrix material, the transition metal oxide-containing material may be present in the form of an inorganic substrate, porous or substantially non porous, having a transition metal oxide-containing coating, e.g., an electronically conductive and/or ferro magnetic transition metal oxide-containing coating, thereon. One particularly useful feature of the present porous membranes is the ability to control the amount of transition metal oxide present to provide for enhanced performance in a specific application, e.g., a specific contacting process. For example, the thickness of the transition metal oxide-containing coating can be controlled to provide such enhanced performance. The coating process of the present invention is particularly advantageous in providing such controlled coating thickness. Also, the thickness of the transition metal oxide-containing coating can be varied, e.g., over different areas of the same porous membrane, such as an asymmetric porous membrane. In fact, the thickness of this coating can effect the size, e.g., diameter, of the pores. The size of the pores of the membrane or porous substrate may vary inversely with the thickness of the coating. The coating process of the present invention iε particularly useful in providing this porosity control.

A heating element, for example, a resistance heatin element, is provided which comprises a three dimensional substrate having an electrically or electronically conductive transition metal oxide-containing coating on at least a portion of all three dimensions thereof. The coated substrate is adapted and structured to provide heat in response, that is, in direct or indirect response, to the presence or application of one or more force fields, for example, magnetic fields, electrical fields or potentials, combinations of such force fields and the like, therein or thereto. An example of such a heating element is one which is adapted and structured to provide heat upon the application of an electrical potential across the coated substrate. Heating elements which are adapted and structured to provide heat in response to the presence of one or more electrical currents and/or electrical fields and/or magnetic fields therein are included in the scope of the present invention. The heat may be generated resistively. In one embodiment, a flexible heating element is provided which comprises a flexible matrix material, e.g., an organic polymeric material in contact with a substrate having an electronically conductive transition metal oxide-containing coating on at least a portion thereof. The coated substrate is adapted and structured as described above.

In addition, an electrostatic dissipation/ electromagnetic interference shielding element is provided which comprises a three dimensional substrate, e.g., an inorganic substrate, having an electrically conductive and/or ferromagnetic transition metal oxide-containing coating on at least a portion of all three dimensions thereof. The coated substrate is adapted and structured to provide at least one of the following: electrostatic dissipation and/or bleed and electromagnetic interference shielding. A very useful application for the products of this invention is for static, for example, electrostatic, dissipation and shielding, particularly for ceramic and polymeric parts, and more particularly as a means for effecting static dissipation including controlled static charge an dissipation such as used in certain electro static paintin processes and/or electric field absorption in parts, such as parts made of ceramics and polymers and the like, as describe herein. The present products can be incorporated directly into the polymer or ceramic and/or a carrier such as a cured or uncured polymer based carrier or other liquid, as for example in the form of a liquid, paste, hot melt, film and the like» These product/carrier based materials can be directly applied to parts to be treated to improve overall performance effectiveness. A heating cycle is generally used to provide for product bonding to the parts. A particular unexpected advantage is the improved mechanical properties, especially compared to metallic additives which may compromise mechanical properties. In addition, the products of this invention can be used in molding processes to allow for enhanced static dissipation and/or shielding properties of polymeric resins relative to an article or device or part without such product or products, and/or to have a preferential distribution of the product or products at the surface of the part for greater volume effectiveness within the part.

The particular form of the products, i.e., fibers, flakes, particles, mats or the like, is chosen based upon the particular requirements of the part and its application, with one or more of flakes, fibers and particles, including spheres, being preferred for polymeric parts. In general, it is preferred that the products of the invention have a largest dimension, for example, the length of fiber or particle or side of a flake, of less than about 0.32 cm, more preferably less than about 0.04 cm and still more preferably less than about 0.02 cm. It is preferred that the ratio of the longest dimension, for example, length, side or diameter, to the shortest dimension of the products of the present invention be in the range of about 500 to 1 to about 10 to 1, more preferably about 250 to 1 to about 25 to 1. The concentration of such product or products in the product/carrier and/or mix is preferably less than about 60 weight%, more preferably less than about 40 weight%, and still more preferably less than about 20 weight%. A particularly useful concentration is tha which provides the desired performance while minimizing th concentration of product in the final article, device or part The products of this invention find particular advantag in static dissipation parts, for example, parts having surface resistivity in the range of about 10⁴ ohms/square t about 10¹² ohms/square. In addition, those parts generall requiring shielding to a surface resistivity in the range o about 1 ohm/square to about 10^s ohms/square and higher find significant advantage for the above products due to thei mechanical properties and overall improved polyme compatibility, for example, matrix bonding properties a compared to difficult to bond metal and carbon-based materials. A further advantage of the above products is their ability t provide static dissipation and/or shielding in advers environments such as in corrosive water and/or electro galvani environments. As noted above, the products have the ability t absorb as well as to reflect electro fields. The uniqu ability of the products to absorb allows parts to be designe which can minimize the amount of reflected electro fields that is given off by the part. This latter property is particularly important where the reflected fields can adversely affect performance of the part.

As described above porous membranes can be used in a wide variety of contacting systems. In a number of applications, the porous membrane provides one or more process functions including: filtration, separation, purification, recovery of one or more components, emulsion breaking, demisting, flocculation, resistance heating and chemical reaction (catalytic or non- catalytic), e.g., pollutant destruction to a non-hazardous form. The resistance heating and chemical reaction functions (applications) set forth herein can be combined with one or more other functions set forth herein for the porous membranes as well as such other related porous membrane applications.

The porous membrane, in particular the substrate, can be predominately organic or inorganic, with an inorganic substrate being suitable for demanding process environments. The porous organic-containing membranes often include a porous organic based polymer matrix material having incorporated therein a three dimensional transition metal oxide-containing material, preferably including an electronically conductive transition metal binary oxide coating, more preferably incorporating a dopant and/or a catalytic species in an amount that provides the desired function, particularly electrical conductivity, without substantially deleteriously affecting the properties of the organic polymer matrix material. These modified polymer membranes are particularly useful in porous membrane and/or electromembrane and/or catalytic processes.

Examples of polymer materials useful in microporous membranes include cellulose esters, poly(vinyl chloride), high temperature aromatic polymers, polytetrafluoroethylene, polymers sold by E. I. DuPont Corporation under the trademark Nafion, polyethyelene, polypropylene, polystyrene, polyethylene, polycarbonate, nylon, silicone rubber, and asymmetric coated polysulfone fiber.

A very convenient application for the coating process and products of this invention is the production of a controlled coating, e.g., a thin coating of transition metal oxide- containing material, on an inorganic substrate, particularly a porous inorganic substrate, to produce a porous membrane. The process provides a new generation of membranes: porous membranes for contacting processes, e.g., as described herein. The selectively in filtration, particularly ultra and micro filtration, can also be enhanced by applying an electrical field and/or an electrical potential to the porous membrane. The electrical field and/or potential can be obtained using a two electrode electrical system, the membrane including a electronically conductive transition metal oxide-containing coating constituting one of the two electrodes, preferably the anode.

As set forth above, porous membranes with inorganic materials can be obtained through powder agglomeration, the pores being the intergranular spaces. Conflicting requirements such as high flow rate and mechanical stability can be achieved using an asymmetric structure. Thus, an inorganic porou membrane is obtained by superimposing a thin microporous film, which has a separative function, over a thick microporou support. For example, conductive transition metal oxid coating onto the surface of filter media can be used as well a onto the surface of flat circular alumina plates. Coate alumina membranes supported on the inner part of sintere alumina tubes designed for industrial ultrafiltration processe can be used. Tube-shaped supports can be used with varyin different chemical compositions, such as oxides, carbides, an clays. Coating of a homogeneous and microporous transition metal oxide-containing layer depends on surface homogeneity of the support and on adherence between the membrane and its support. Superior results can be obtained with particulate alumina. The inner part of the tube has a membrane comprising a layer, e.g., in the range of about 10 to about 20 microns thick, with pores, e.g., having diameters in the range of- about 0.02 to about 0.2 microns sized for microfiltration purposes. The main feature of such a membrane is uniform surface homogeneity allowing for the transition metal oxide-containing coating to be very thin, e.g., less than about one micron in thickness.

In addition to the direct and/or indirect heating of gases, particularly non-reactive gases and/or non-combustible gases, the products of this invention are particularly useful in heat exchange relationship with chemically reactive including combustible gases. In a typical application, the gas is heated (direct and/or indirect) to a temperature effective to initiate reaction and/or combustion of such gases which reaction if exothermic will produce heat thereby increasing the overall temperature of the gases and heated surfaces, particularly downstream surfaces. A particularly useful application of the above products is in the combustion of gases, particularly combustion converters including catalytic converters as described above under catalyst products and applications. In the various applications set forth above for the heating of gases, particularly preferred substrates are particles and a multi-cell/channel monolith, as set forth and described above. The multi-cell/channel monolith has excellent mechanical properties and is particularly useful for high gas velocity type applications, i.e, in the treatment of combustion gasses.

The catalyst surface temperature is particularly important for initiating reaction, continuing the reaction and effectively utilizing the heats of combustion. In order to initiate a chemical reaction, particularly, a combustion reaction, such as in a catalytic convertor, it is preferred to have a surface and/or catalyst heat up rate which will allow for rapid initiation of the exothermic reaction. Typical heat up rates for transition metal oxide surfaces is from about 100°C per second up to about 700°C per second. Typically, a heat up rate of about 150°C per second to about 450°C per second will achieve a rapid catalyst and/or surface heat transfer to initiate chemical reactions including combustion. As set forth above, the heat up rates will be in part determined by the conductivity and other electrical components. Depending upon the application and the requirements of voltage, current and overall power requirements, the conductivity/resistivity of the transition metal oxide coating, can be controlled to design requirements. For example, the dopant level can be increased and/or decreased to obtain a design bulk conductivity. In addition, the thickness of the transition metal oxide coating can be varied and/or a degree of coating substrate interaction can be introduced into the coating design conductivity. In addition, other metal compounds, such as metal oxides, for example, copper, iron can be incorporated into for example a tin oxide coating to, for example, increase the resistivity of the coating for a particular application design requirement. In the case of the latter, it is preferred to have a uniform change in resistivity as opposed to the presence of insulating occlusions from the reaction of a component such as an oxide forming component with, for example, the transition metal oxide forming compound. As set forth above, it is preferred to reduce substantial deleterious interaction of substrate, coatings and catalys which can adversely affect the design conductivity/resistivit for the particular heating application, including deleteriou interactions that may affect the activity and/or activit maintenance of the resistively heated catalyst.

Another very useful application for the products of thi invention is for the joining of parts, particularly polymeri parts, and as a means for effecting the sintering or curing o parts, such as ceramics, curable polymers, for exampl thermoset and rubber based polymers and the like. The products can be incorporated directly into the polymer or ceramic and/o a carrier such as a cured or uncured polymer based carrier or other liquid, as for example in the form of a liquid, paste, hot melt, film and the like. These product/carrier based materials can be directly applied to parts to be joined and resistance heating particularly induction heating used to raise the temperature and bond the parts together at a joint such as through polymer melting and/or curing. A particular unexpected advantage is the improved mechanical properties, especially compared to metallic susceptors which may compromise mechanical properties. In addition, the products of this invention can'be used in molding processes to preferentially allow the rapid heating and curing of polymeric resins, and/or to have a preferential distribution of the products at the surface of the parts for subsequent joining of parts. The particular form of the products, i.e., fibers, spheres, flakes, particles, mats or the like, is chosen based upon the particular requirements of the part and its application, with one or more of flakes, fibers and particles being preferred for joining or bonding parts. In general, it is preferred that the products of the invention have a largest dimension, for example the length of a fiber or side of a flake, of less than about 0.32 cm, more preferably less than about 0.04 cm and still more preferably less than about 0.02 cm. The concentration of such product or products in the product/carrier and/or mix is preferably less than about 50 weight%, more preferably less than about 20 weight%, and still more preferably less than about 10 weight%. A particularly useful concentration is that which provides the desired heating while minimizing the concentration of product in the final part.

Another unique application of the present invention combines the stability of the transition metal oxide containing coating, particularly tin oxide, particularly at high temperatures and/or in demanding oxidizing environments, with the need to protect a structural element and/or to provide a fluid, i.e., gas and/or liquid, impervious material. Such structural elements are suitable for use at high temperatures, preferably greater than about 190° C. , more preferably greater than about 800°C. or even greater than about 1080°C.

The coating process of this invention, in addition, can uniformly coat three dimensional woven structures, particularly in the various state, to effectively seal off diffusion of gases and/or liquids between surfaces. For example, ceramic fibers can be woven into structures or structural elements, sealed off between surfaces, and used in high temperature applications. Such applications include gas and/or oil radiant and post combustion burner tubes, turbine engine components, and combustion chambers. For the latter, such structures can also contain one or more catalytically active materials that promote combustion, such as hydrocarbon combustions.

A particularly unique application that relies upon stable electronic conductivity and the physical durability of the products of this invention are dispersions of conductive material, such as powders, in fluids, e.g., water, hydrocarbons, e.g., mineral or synthetic oils, whereby an increase in viscosity, to even solidification, is obtained when an electrical field is applied to the system. These fluids are referred to as "field dependent" fluids which congeal and which can withstand forces of shear, tension and compression. These fluids revert to a liquid state when the electric field is turned off. Applications include dampening, e.g., shock absorbers, variable speed transmissions, clutch mechanisms, etc. The products of this invention which can be particularly useful for forming field dependent fluids are particulate as set forth above, particularly as powders. Such particulate can be for example, spheres, fibers, flakes, i.e., platelet, and such other particulates, and powders. Typical examples of such transition metal oxide coated particles including property modifications are set forth above under catalysts resistance heating and electrostatic and EMI shielding particles. Such particles can have incorporated therein various dopants to modify conductivity and/or other components can be incorporate for a particular property, including various metal type components. In addition, various inorganic substrates are set forth above which substrates are particularly useful in producing the particles for use in field dependent fluids. The coated substrate including the transition metal oxide, preferably electrorheology electronically conductive transition metal oxide and/or optionally electrorheology polarizable transition metal oxide and/or at least one additional component in an amount effective to promote field dependent fluid performance, is particularly useful as field dependent fluids including electric and magnetic field dependence, particularly electric field. Preferably the additional component is a polarizable component or conductivity modified in an amount effective to promote such fluid performance. Thus the promoting effect of the component may be enhanced by the presence of an electrical field in proximity to the component/particle. Thus, the transition metal oxide, preferably on a substantially non-electronically conductive substrate, e.g., a particle, can provide an effective and efficient electric field dependent fluid, including those which occur or are enhanced when an electric field is applied in proximity of the particle. Thus, it has been found that the presently coated substrates are useful as active electrorheological fluid properties. As noted above, it is preferred that the transition metal oxide containing substrates be electronically conductive and/or polarizable. Although doped transition metal oxides are particularly useful, particularly doped tin oxide, other interacting components may be incorporated in the present particle to provide the transition metal oxide with the desired electronic and/or polarizable properties. For example, antimony may be employed for example, as a tin oxide dopant.

Such other interacting components may be incorporated into the final particle, transition metal oxide containing coated substrates using one or more processing techniques substantially analogous to procedures useful to incorporate specific dopants, e.g., fluorine as described above.

As set forth above, the transition metal oxide particles are present in the fluid in the amount to enhance the field dependent fluid performance. In addition, the conductivity and/or reciprocal resistivity of the transition metal oxide particle is of a value which promotes the overall performance of the field dependent fluid, i.e., enhances electrorheo- logical properties of the fluid. Typically the resistivity of the tin dioxide particle is within the range from about 10³ to about 10⁹ ohm cm, more preferably from about 10¹ to about 10³ ohm cm and still more preferably, from about 10 ohm cm to about 10² ohm cm. The conductivity of the transition metal oxide particle can be controlled by the type of dopant, the concentration of dopant, the processing conditions in order to obtain a resistivity within the preferred ranges as set forth above and with improved electrorheological modifying properties. In addition to the above modifications to obtain a given conductivity other components can be incorporated into the transition metal oxide coating such as a moderate to high resistance type of material such as silica or other oxides referred to above which produces a transition metal oxide coating having optimized eletrorheological properties.

In addition to electrical conductivity as set froth above, the polarizability of the transition metal oxide coating can be modified through the addition of a component such as to enhance the overall polarizability of the transition metal oxide particle which enhanced polarizatiliby can improve the overall electrorheological properties of the fluid. For example, the transition metal oxide coating can be modified to form surface hydrates which are responsive to electric fields and produce a reversible change in electrorheological properties. Other components, particularly polar components, more particularly organic polar components such as surface active agents, alkanol amines such as low molecular weight alkanol amines, alkyl amines and water can in addition be used as polarization components. Such additional components which alter the polarization properties of the transition metal oxide coating and can product field dependent fluids which are useful at elevated temperatures, including for certain fluids use above 70°C or even above 100°C.

The stability and durability for the present transition metal oxide materials are believed to make them very useful in field dependent fluids in more aggressive and/or more harsh environments, particularly high temperature, and/or pressure and/or oxidation environments.

Certain metal components associated with the transition metal oxide particle may be employed, provided that they function to enhance electrorheo- logical properties and/or an application defined property. Among the useful metal components are those selected from components of the transition metals, the rare earth metals, certain other components and mixtures thereof, in particular, gold, silver, copper, vanadium, chromium, cobalt molybdenum, tungsten zinc, indium, the platinum group metals, i.e., platinum, palladium and thorium, iron, nickel, manganese, cesium, titanium, etc. Although metal containing compounds may be employed, it is preferred that the metal components included with the coated substrate comprise elemental metal and/or metal in one or more active oxidized forms, for example, Cr₂0₃, Ag₂0, etc.

The preferred substrate materials include a wide variety of inorganic materials including high surface area materials, particularly inorganic oxides and carbon as set forth above, particularly under the catalysts resistance heating and shielding products of this invention. Additional substrates include for example, alumina, silica, zirconia, magnesia, boria, phosphate, titania, ceria, thoria and the like, as well as multi-oxide type supports such as alumina-phosphorous oxide, silica alumina, zeolites, zeolite modified inorganic oxides, e.g., silica alumina and the like. As set forth above, substrate particle materials can be in many forms and shapes, especially shapes which are not flat surfaces, i.e., non line- of-site particulate materials and particularly, spheres. The substrate can be used as is or further processed such as by sintering of powered materials into large aggregates. The aggregates can incorporate other powders, for example, other oxides, to form the aggregates.

As set forth above, the particles include for example, spheres, fibers, flakes, other irregularly shaped geometry such as aggregates and alike. In general the particle size can vary over a wide range, typically a particle size maximum width of from about 0.04 microns up to a width representing about 10% of the design gap between electrodes which form the electric field means associated with the use of the field dependent fluid. More preferably, the range of the width of the particle is from about 1 to about 100 microns still more preferably, from about 5 to about 50 microns. The width of the particles can be adjusted to provide various degrees of packing densities in the fluid which packing densities can include a bi-modal type of distribution of particle sizes. It is preferred that the particles comprise a majority of mono particles, more preferably, a predominant proportion. The use of mono particles reduces the tendency of the particles to sheer down to smaller size particles which shear down may accompany the use of particle aggregates in field dependent fluids. In addition, it is preferred to have a particle aspect ratio, i.e., the maximum particle width divided by the minimum particle width of less than about 20 to 1, still more preferably less than about 10 to- 1 and still more preferably, less than about 5 to 1. One of the preferred shapes is spheres wherein the aspect ratio approaches 1 and/or is 1. In practice the spherical particles which are preferred for use in the composition of this invention, have a roundness associated with such particles generally greater than about 70%, still mo preferably greater than about 85% and still more preferabl greater than about 95%.

As set forth above, a particularly preferred particle a spherical particle, particularly spheres within the partic size and roundness ranges set forth above. The spheres c improve overall field dependent fluid performance, particular in reducing adverse particle effects on the fluid such dielectric breakdown. A particularly unique embodiment of t present invention is the use of hollow spheres, particular within the particle size and roundness ranges as set for above. Such spheres are hollow i.e. contain one or more clos cell voids hereinafter referred to as hollow spheres and a designed to be density compatible with the fluid. The densi compatible hollow spheres have a density in the range of fr about 60% to about 140% of the density of the fluid, mo preferably from about 70% to about 130% of the density of t fluid, still more preferably from about 80% to about 120% the density of the fluid and still more preferably, from abo 90% to about 110% of the density of the fluid. Thus, f example, the density of the fluid can vary according to t type of fluid utilized in the field dependent fluid, such from about 0.95 g per cc up to about 1.95 g per cc for certa chlorinated aromatic fluids. The density compatibility of t hollow spheres relates to the particular fluid, includi blends of fluids utilized as the field dependent fluid. Th density compatibility provides improved stability of the hollo spheres particulate in the fluid, particularly where settlin out the particles can adversely effect overall performance o the field dependent fluids and/or where such sedimentation ca cause premature failure of the device.

As set forth above, the spheres can be inorganic and fo example, carbon and/or inorganic oxide. The preferre inorganic oxides can be for example alumino silicates, silica sodium borosilicate, insoluble glass, soda lime glass, sod lime borosilicate glass, silica alumina, as well as suc glasses and ceramics, modified with titanium dioxide and/o small amounts of iron oxide. The density of the hollow spheres can be designed to be density compatible with the fluid by the density of the inorganic material itself, the hollow and or void volume and the thickness of the wall and the density of surface component on the sphere. For a hollow sphere the aspect ratio, i.e., the diameter of the sphere divided by the thickness of the wall, in part defines both the density of the hollow sphere, as well as the buckling pressure of the sphere. Thus as the aspect ratio decreases, the density of the hollow sphere increases and in general, the crush strength of the hollow sphere increases. Of additional significance is the ability of the hollow sphere under high sheer conditions to provide improved mechanical stability, particularly at aspect ratios which provide the requisite wall thickness and density compatibility. Thus for example, hollow spheres for use in field dependent fluids can be designed for density compatibility at high crush strengths and sheer rates, for example, less than about 20% and even less than about 10% breakage at isostatic pressures of greater than 6,000 psi, even up to about 60,000 psi.

As set forth above, the unique hollow spheres having fluid density compatibility can be coated with transition metal oxide including such additional components as set forth above. In addition, it has been found that the fluid density designed coated particles can improve the overall performance of materials that have been shown to exhibit an electrorheological effect. Thus for example, fluid density coated compatible hollow spheres can have an electronically conductive and/or polarizable surface component associated therewith, including components which are incorporated during the processing to produce such fluid density compatible materials. For example, alumino silicates, organic polyelectrolytes, organic polyampholytes, organic semiconductors, water, polar organic compounds such as alcohols, amines, amides, polyhydroxy organic compounds and various other surfactant materials which provide a polarizable effect on the surface can be incorporated on the surface of the coated hollow sphere. The surface area can be optimized for the transition metal oxide coating and/or other components, and/or other conductivity and/or polarizable components, by the selection of starting materials, porosity forming components and their concentration and geometry. Such optimization also takes into consideration the final end use application of the substrate. Porosity can also be increased by directly leaching the preformed substrate within an acid medium, i.e., nitric acid, to selectively remove for example ceramic constituents for example magnesia and alumina. Such leaching cannot only increase porosity but also the surface areas of the substrate. Typical substrate surface areas can range from about 0.1 to about 2 meters square per gram up to about 20 or even up to about 40 or higher meters square per gram, with the higher areas generally resulting from leached and/or coated substrates.

It is generally preferred to have a high surface area in order to optimize activity for a particular application. As set forth above, the surface area can be increased by, for example, leaching and/or by the application of a surface coating such as a wash-coat which provides for a high surface area surface on the substrate. It is preferred to incorporate other active components as set forth above on a high surface area for improved overall effectiveness and activity. As set forth above, it is preferred to have macro pores when a subsequent surface coat is being applied to the substrate. Such subsequent coatings can include, for example, a barrier coat, a wash coat, and/or the tin oxide coating on the substrate surface. Other active components may be included with the coated substrate and/or substrate using any one or more of various techniques, e.g., conventional and well known techniques. For example, metal can be included with the coated substrate by impregnation; electro-chemical deposition; spray hydrolysis; deposition from a molten salt mixture; thermal decomposition of a metal compound or the like. The amount of a component included is sufficient to perform the desired functions, ar_*i varies from application to application.

In addition to the above described applications, zinc oxide is particularly useful in applications which require a large electro mechanical coupling coefficient, such as transducers in surface acoustic wave devices and microwave delay lines and various other acoustic and piezo devices. Such properties also have applications in telephone equipment, strain gauges, acoustic optical devices, i.e., laser deflectors and Fourier transform devices.

The potential applications for superconducting materials include large-scale, passive application such as shields or waveguides, superconductors screen or reflect electromagnetic radiation and uses range from coatings on microwave cavities to shielding against electromagnetic pulses and bearings. Repulsive forces of superconductors excluding magnetic fields provide for noncontact bearings.

In addition, high-current, high-field, applications include magnetic imaging/scientific equipment, such as, Superconducting magnets for nuclear magnetic resonance and imaging spectrometers and particle accelerators; Magnetic separation, such as, magnets used for separation and purification of steel scrap, clays, ore streams, stack gases, and desulfurizing coal. Magnetic levitation such as high-speed train systems; electromagnetic launch systems which can accelerate objects at high velocity. Possible uses include rapidly repeatable, i.e., earth satellite launching, aircraft catapults, and small guns for military uses. Other magnet applications include powerful magnets in compact synchrotrons for electronic thin-film lithography, crystal growth, magnetohydrodynamic energy conversion systems, and ship propulsion by superconducting motors or by electromagnetic fields. Other high current high field applications include electric power transmission, such as, transmission cables, carrying more current than conventional conductors without loss. Such conductors must be mechanically rugged and operate under high field and high current conditions; energy storage, such as, large superconducting magnetic coils buried in the ground that can store vast amounts of electrical energy, without power loss, in persistent, circulating currents; load leveling for utilities and as power sources for military systems such as pulsed lasers; generators and motors, such as, low-temperature system operating with liquid helium. Motors can be used in ship propulsion, railway engines, and helicopters. In the area of electronics; applications include passive devices, such as, high-speed wire interconnects in electronic circuits. digital devises, such as, superconducting components, based on Josephson junctions, to be used as switches or in computer logic and memory. In addition, the potential for hybridized semiconductor/superconductor electronic devices may provide yet unknown applications and devices; sensors, such as, superconducting quantum interference devices, SQUIDs) made from Josephson junctions which are extremely sensitive detectors of electromagnetic signals. Low- temperature SQUIDs are used in biomedical, geophysical, and submarine or airplane detection, infrared and microwave sensors.

Other devices include analog-to-digital convertors, voltage standards, signal processors, microwave mixers, filters, and amplifiers.

The copper oxide coated substrate, such as the 1,2,3 and 1,2,4 copper oxide coated substrate, of the present invention may be, for example, a component itself or a component of a composite together with one or more matrix materials. The composites may be such that the matrix material or materials substantially totally encapsulate or surround the coated substrate, or a portion of the coated substrate may extend away from the matrix material or materials.

The iron oxide/substrate combinations, e.g., the iron oxide coated substrates, of the present invention are useful in other applications as well. The applications for the spinel ferrites can be grouped into several main categories: main cores, and linear, power, and recording-head applications.

Magnetic-core memories are based on switching small turoidal cores of spinel ferrite between two stable magnetic states. Such core memories are used in applications where ruggedness and reliability are necessary, e.g., military applications.

The linear or low signal applications are those in which the magnetic field in the ferrite is well below the saturation level and the relative magnetic permeability can be considered constant over the operating conditions.

The manganese-zinc-ferrite materials characteristically have higher relative permeabilities, higher saturation magnetization, lower losses, and lower resistivities. Since the ferromagnetic resonance frequency is directly related to the permeability the usual area of application is below 2 MHz. At low signal levels, ferrite cores are used as transformers, low frequency and pulse transformers, or low energy inductors. As inductors, the manganese-zinc-ferrites find numerous applications in the design of telecommunications equipments where they must provide a specific inductance over specific frequency and temperature ranges. Nickel-zinc- ferrites with lower saturation magnetization, generally lower relative magnetic permeabilities, and lower resistivities (10⁶.cm) , produce ferromagnetic resonance effects at much higher frequencies than the manganese-zinc-ferrites. They find particular application at frequencies from 1 to 70 MHz (46) . By adjustment of the nickel-zinc ratio it is possible to prepare a series of materials covering the relative permeability range of 10-2000. These rods, high frequency power transformers, and pulse transformers. A variety of materials have been developed to serve these applications.

The lower magnetic losses of ferrite materials and its higher resistance (lOohm.cm) compared with laminated transformer steel permits ferrite cores to be used as the transformer element in high frequency power supplies. Commonly known as switched-mode power supplies, they operate at frequency of 15-30 khz and offer higher efficiencies an smaller size than comparable laminated steel transformers.

Television and audio applications include yoke rings fo the deflection coils for television picture tubes, flybac transformers, and various convergence and pincushion intortio corrections, as well as antenna rods.

Manganese-zinc and nickel-zinc-spinel ferrites are ;use in magnetic recording heads for duplicating magnetic tapes an the recording of digital information. Most recording heads ar fabricated from polycrystalline nickel-zinc-ferrite fo operating frequencies of 100kHz to 2.5 GHz.

The unique properties of hexagonal ferrites are lo density, and high coercive force. The ceramic magnet can be used in d-c permanent magne motors, especially in automotive applications, such windo life, flower, and windshield-wiper motors.

Other grades of barium and strontium ferrite materia have been developed for similar applications. Other applications of hexagonal ferrites are used i self-resonant isolators where the strong magnetocrystallin anisotropy permits a resonator without laded-c magnetic biasin fields.

Hexagonal ferrites are also used as magnetic biasin components in magnetic bubble memories.

Certain of these and other aspects the present invention are set forth in the following description of the accompanying drawing.

Brief Description of the Drawings

Fig. l is a block flow diagram illustrating a process for producing the present coated substrates.

Detailed Description of the Drawings The following description specifically involves the coating of randomly oriented, non-woven mats of C-glass fibers. A process system according to the present invention shown generally at 10, includes a preheat section 12, a coatin section 14, an equilibration section 16 and a oxidation/sintering section 18. each of these sections is i fluid communication with the others. Preferably, each of thes sections is a separate processing zone or section.

First gas curtain 20 and second gas curtain 22 provid inert gas, preferably nitrogen, at the points indicated, and, thereby effectively insure that preheat section 12, coatin section 14 and equilibrium section 16 are maintained in a substantially inert environment. First exhaust 24 and second exhaust 26 are provided to allow vapors to exit or be vented from process system 10.

Randomly oriented woven mats of C-glass fibers from substrate source 28 are fed to preheat section 12 where the mats are preheated up to a predetermined temperature for a time of 1 to 3 minutes at atmospheric pressure to reach thermal equilibrium. These mats are composed of from 8 micron to 35 micron diameter C- or T-glass randomly oriented or woven fibers. The mats are up to 106.7 cm wide and between 0.147 cm to 0.442 cm thick. The mats are fed to process system 10 at the rate of about 30.5 cm to 152.4 cm per minute so that the fiber weight through is about 0.64 gms to about 953.6 grams per minute. The preheated mats pass to the coating section 14 where the mats are contacted with for example an anhydrous mixture of 70% to 95% by weight of stannous chloride and 5% to 30% by weight of stannous fluoride from raw material source 30. This contacting effects a coating of this mixture on the mats. This contacting may occur in a number of different ways. For example, the SnCl₂/SnF₂ mixture can be combined with nitrogen to form a vapor which is at a temperature of from about 25°C to about 150°C higher than the temperature of the mats in the coating section 14. As this vapor is brought into contact with the mats, the temperature differential between the mats and the vapor and the amount of the mixture in the vapor are such as to cause controlled amounts of SnCl₂ and SnF₂ t condense on and coat the mats.

The mats in the coating section 14 are at a temperatur of up to about 375°C, and this section is operated at slightl less than atmospheric pressure. Afterthe SnCl₂/SnF₂ coatin is applied to the fiber mats, the fiber mats are passed to th equilibration section 16. Here, the coated fiber mats are maintained, preferably at a higher temperature than in coating section 14, in a substantially inert atmosphere for a period of time, preferably up to about 10 minutes, to allow the coating to more uniformly distribute over the fibers. In addition, if the fluorine component is introduced onto the fiber mats separate from the stannous chloride, the time the coated fiber mats spend in the equilibration section 16 results in the dopant component becoming more uniformly dispersed or distributed throughout the stannous chloride coating. Further, it is preferred that any vapor and/or liquid which separate from the coated fiber mats in the equilibration section 16 be transferred back and used in the coating section 14. This preferred option, illustrated schematically in Fig. 1 by lines 32 (for the vapor) and 34 (for the liquid) increases the effective overall utilization of SnCl₂ and SnF₂ in the process so that losses of these components, as well as other materials such as solvents, are reduced. The coated fiber mats are passed from the equilibration zone 16 into the sintering zone 18 where such fiber mats are contacted with an oxidizer, such as an oxygen-containing gas, from line 36. The oxidizer preferably comprises a mixture of air and water vapor. This mixture, which preferably includes about 1% to about 50%m more preferably about 15% to about 35%, by weight of water, is contacted with the coated fiber mats at atmospheric pressure at a temperature of about 400°C to about 550°C for up to about 10 minutes. Such contacting results in converting the coating on the fiber mats to a fluorine doped tin metal dioxide coating. The fluorine doped tin metal oxide coated fiber mats product, which exits sintering section 18 via line 38, has useful electric conductivity properties. This product preferably has a coating having a thickness in th range of about 0.5 microns to about 1 micron, and i particularly useful as a component in a lead-acid battery.

EXAMPLE 1 Stannous chloride powder is applied to a 66 cm by 66 c glass fiber non woven mat in the form of a powder (10 to 12 microns in average particle diameter) is shaken from a powde spreading apparatus positioned 61 cm to about 152 cm above th mat. An amount of stannous fluorine powder (10 to about 125 microns in average particle diameter) is added directly to the stannous chloride powder to provide fluoride dopant for the final transition metal oxide product. The preferred range to achieve low resistance transition metal oxide products is about 15% to about 20% by weight of stannous fluoride, based on the total weight of the powder. The powder-containing mat is placed into a coating furnace chamber at 350°C and maintained at this temperature for approximately 20 minutes. During this time, a downflow of 9.0 liters per minute of nitrogen heated to 350°C to 350°C is maintained in the chamber. In the coating chamber the stannous chloride powder melts and wicks along the fiber to^' from a uniform coating. In addition, a small cloud of stannous chloride vapor can form above the mat. This is due to a small refluxing action in which hot stannous chloride vapors rise slightly and are then forced back down into the mat for coating and distribution by the nitrogen downflow. This wicking and/or refluxing is believed to aid in the uniform distribution of stannous chloride in the coating chamber.

The mat is when moved into the oxidation chamber. The oxidation step occurs in a molecular oxygen-containing atmosphere at a temperature of 525°C for a period of time of 10 to 20 minutes. The mat may be coated by this process more than once to achieve thicker coatings.

EXAMPLE 2 A substrate made of alumina carbide was contacted with a powder mixture containing 95 mol% ZnCl₂ and 5 mol% SnCl₂. This contacting occurred at ambient temperature in an air atmosphere at about atmospheric pressure and resulted in a coatin containing ZnCl₂ and SnCl₂ being placed on the substrate.

This coated substrate was then heated to 375°C an allowed to stand in an argon atmosphere at about atmospheri pressure for about 5 minutes. The coated substrate was the fired at 600°C for 5 minutes using flowing, at the rate of one (1) liter per minute, water saturated air at about atmospheric pressure followed by 10 minutes sintering at 700°C. This resulted in a substrate having a Sn0₂ doped zinc oxide coating with excellent electronic properties.

EXAMPLE 3 A substrate made of yttria stabilized zirconia was contacted with a molten mixture containing CuCl, BaO_z and YC1₃ in a ratio to provide an atomic ratio of Y, Ba, Cu of 1, 2 , 3, or 1, 2, 4, in the final product. This contacting occurred at 350°C in an argon atmosphere at about atmospheric pressure and resulted in a coating being placed on the substrate.

The coated substrate was then heated to 475°C and allowed to stand in an argon atmosphere at about atmospheric pressure for about 20 minutes. The coated substrate was then fired at 800°C for 20 minutes using flowing, at the rate of one (l) liter per minute, water saturated air at about atmospheric pressure.

The material was further annealed at 500°C for 24 hours. This resulted in a substrate having a copper oxide coating with excellent electronic properties.

The present methods and products, illustrated above, provide outstanding advantages. For example, the copper oxide coated substrates, particularly thin film prepared in accordance with the present invention have improved, i.e., reduced, electronic defects, relative to substrates produced by prior methods.

EXAMPLE 4

Cuprous chloride powder is applied to multiple fibers of alumina (random mat) in the form of a powder (10 to 125 microns in average particle diameter) shaken from a powder spreading apparatus positioned 61 cm to about 152 cm above the spread multiple filament. An amount of Ycl₃ and Baθ₂ powder (10 to about 125 microns in average particle diameter) is added directly to the cuprous chloride powder to provide the necessary stoichiometry for the final copper oxide product. The powder-containing mat is placed into a coating furnace chamber at 450° C and maintained at this temperature for approximately 20 minutes. During this time a downflow of 9.0 liters per minute of nitrogen heated to 450° C to 500° C is maintained in the chamber. In the coating chamber the cuprous chloride powder melts and wicks along the fiber to form a uniform coating. The Ycl₃ is in a finely dispersed form from about 0.2 to about 2 micron for ease of wicking. In addition, a small cloud of cuprous chloride vapor can form above the mat. This is due to a small refluxing action in which hot cuprous chloride vapors rise slightly and are then forced back down into the mat for coating and distribution by the nitrogen downflow. This wicking and/or refluxing is believed to aid in the uniform distribution of cuprous chloride and additional components in the coating chamber.

The fiber is then moved into the oxidation chamber. The oxidation step occurs in a molecular oxygen-containing atmosphere at a temperature of 800°C for a period of time of 1 hour. The fiber may be coated by this process more than once to achieve thicker coatings and/or removed and annealed in a finishing oxidation step to develop the optimum crystal structure for conductivity.

EXAMPLE 5

An iron chloride powder is applied to a 66 cm by 66 cm silica fiber non woven mat (10 to 125 microns in average particle diameter) shaken from a powder spreading apparatus positioned 61 cm to about 152 cm above the mat. An amount of indium mono chloride powder (10 to about 125 microns in average particle diameter) is added directly to an iron chloride powder to provide a dopant for the final iron oxide product. The preferred range to achieve low resistance iron oxide products is about 2% to about 15% by weight of indium chloride, based on the total weight of the powder. The powder-containing mat is placed into a coating furnace chamber at 375° C and maintained at this temperature for approximately 20 minutes. During this time a downflow of 9.0 liters per minute of nitrogen heated to 350° C to 450° C is maintained in the chamber.

In the coating chamber the chloride powder melts and wicks along the fiber to form a uniform coating. In addition, a small cloud of iron metal chloride vapor can form above the mat. This is due to a small refluxing action in which hot iron and indium chloride vapors rise slightly and are then forced back down into the mat for coating and distribution by the nitrogen downflow. This wicking and/or refluxing is believed to aid in the uniform distribution of iron chloride in the coating chamber. The mat is then moved into the oxidation chamber. The oxidation step occurs in a molecular oxygen-containing atmosphere at a temperature of 525°C for a period of time of 1 to 5 minutes followed by^*increasing the temperature to 800° for a period of time of from 10 to 40 minutes in the presence of a sulfur oxide forming source. The mat may be coated by this process more than once to achieve thicker coatings.

EXAMPLE 6

A horizontal continuous chemical vapor deposition (CVD) furnace was evaluated for the coating of the non-woven fabric of Example 1. The furnace is described in Circuits

Manufacturing, October 1975. The furnace temperature could be profiled to reach approximately 560°C and has been used to produce transition metal dioxide coated flat glass in one pass.

The CVD furnace used tetramethyl tin or stannic chloride as the vaporous transition metal source. The fluoride dopant source used with tetramethyl tin was trifluorobromo methane and with stannic chloride was hydrofluoric acid. The oxidant in the CVD furnace was a combination of water (vapor) and methanal. The non-woven mat used to evaluate the state of the art process equipment, was the same non-woven mat used in Examples 1. The process was evaluated using the highest temperature attainable in the oven using the slowest belt speed and at conditions to maximize reactant deposition and formation of a fluoride doped transition metal dioxide. A series of 25 process runs were made in the furnace and it was determined that essentially no deposition and coating was obtained on the non-woven mat. The same conditions with flat glass produced highly conductive transition metal dioxide coatings on soda lime glass.

EXAMPLE 7 An electrolysis tin oxide deposition method that had been used experimentally on flat surfaces was evaluated for coating non-woven mat of the type set forth in examples 1 and 8. The method was based on the controlled homogenous precipitation of transition metal hydrate hydroxide from an aqueous solution of stannic chloride complexed with ammonium chloride. In the method, a catalyst (silver nitrate) is added in order to initiate precipitation. Precipitation begins when the substrate is immersed and the pH is brought up to 7.5 with sodium hydroxide. The results obtained when a non-woven fabric was utilized in the process were very low deposition rates, poor materials utilization, poor coating adhesion, poor fiber coating, i.e.,' clumps, poor continuity of the fiber, very low to zero dopant incorporation and a very high resistivity transition metal oxide.

The results set forth in examples 6 and 7 demonstrate the difficult and substantial problems associated with the coating of shielded surfaces and/or 3-D type substrates. In example 6, the substitution of a 3-dimensional, non-woven fabric for a flat glass substrate in a unit which is used to effectively coat flat glass were unsuccessful in its application to a 3- dimensional substrates and/or substrates with shielded surfaces. In addition, example 7 demonstrates the difficulty in processing 3-D substrates, i.e., very high resistivity and in addition, the difficult problem of incorporation of a dopant to provide enhanced electrical conductivity. A comparison between example 1 and examples 6 and 7 demonstrate the unexpected, unique advantages and advances of the processes of this invention and the unique products for use in a wide variety of applications. While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

Claims

1. A process for producing an electrically conductive or ferro magnetic coated three-dimensional inorganic substrate comprising: contacting said substrate which includes external surfaces and shielded surfaces which are at least partially shielded by other portions of said substrate with a composition comprising a transition metal oxide forming compound at conditions effective to form a transition metal oxide forming containing coating on at least a portion of said three- dimensional substrate; including at least a portion of the shielded surfaces of said substrate; contacting said substrate having said transition metal oxide forming containing coating thereon with an oxidizing agent at conditions effective to convert the transition metal oxide forming component to a transition metal oxide and form a transition metal oxide coated substrate and recovering an electrically conductive or ferromagnetic transition metal oxide coated three dimensional substrate.

2. The process of claim 1 wherein the transition metal is selected from the group consisting of tin, copper, zinc, iron, chromium, tungsten, indium, molybdenum, titanium and mixtures thereof.

3. The process of claim 2 wherein the transition metal is selected from the group consisting of copper, zinc, iron, chromium and titanium.

4. The process of claim 1 wherein said transition metal oxide forming compound is a transition metal chloride and is a solid at 25°C.

5. The process of claim 1 wherein said substrate is contacted with an interacting component in anyone or more of said process steps and forming a substrate having one or more interacting components on at least a portion of said substrate including at least a portion of the shielded surfaces of said substrate.

6. The process of claim 5 wherein the interacting component is present in an effective amount to modify electrical conductivity, ferromagnetic or catalyst properties.

7. The process of claim 1 wherein said substrate with said transition metal oxide forming compound containing coating is maintained for a period of time at conditions effective to do at least one of the following: (1) coat a larger portion of said substrate with said transition metal oxide forming compound containing coating; (2) distribute said transition metal oxide forming compound containing coating over said substrate; and (3) make transition metal oxide forming compound-containing coating more uniform in thickness.

8. The process of claim 1 wherein said substrate is in a form selected from the group consisting of spheres, extrudates, flakes, fibers, fiber rovings, chopped fibers, fiber mats, porous substrates, rings, irregularly shaped particles and multi-channel monoliths.

9. The process of claim 3 wherein said substrate is in a form selected from the group consisting of spheres, extrudates, flakes, fibers, chopped fibers, porous substrates, rings and irregularly shaped particles.

10. The process of claim 5, wherein said interacting component is a catalyst material and said catalyst material includes at least one metal selected from the group consisting of gold, silver, copper, vanadiium, chromium, tungsten, zinc, indium, antimony, the platinum group metals, iron, nickel, manganese, cesium and tetanium.

11. A process for coating surfaces of a three- dimensional substrate with an electrically conductive or ferromagnetic transition metal oxide coating which comprises: contacting said substrate with a composition comprising a transition metal oxide precursor powder at conditions effective to from a coating containing transition metal oxide precursor on at least a portion of the substrate; maintaining said coated substrate at a temperature above the liquidus temperature of said transition metal oxide precursor and maintaining said coated substrate for a period of time at conditions including said increased temperature effective to do at least one of the following: (2) coat a larger portion of said substrate with said coating containing transition metal oxide precursor; (2) distribute said coating containing transition metal oxide precursor over said substrate; and (3) make said coating containing transition metal oxide precursor more uniform in thickness and contacting said coated substrate with an oxidizing agent at conditions effective to convert said transition metal oxide precursor to transition metal oxide on at least a portion of all three dimensions of said substrate and recovering an electrically conductive or ferro magnetic transition metal oxide coated three-dimensional substrate.

12. The process of claim 11 wherein the transition metal is selected from the group consisting of copper, zinc, iron, chromium, tungsten, indium, molybdenum, titanium and mixtures thereof.

13. The process of claim 11 wherein said transition metal oxide forming compound is a transition metal chloride and is a solid at 25° C.

14. The process of claim 11 wherein said substrate is contacted with an interacting component in anyone or more of said process steps and forming a substrate having one or more interacting components on at least a portion of said substrate including at least a portion of the shielded surfaces of said substrate.

15. The process of claim 14 wherein the interacting component is present in an effective amount to modify electrical conductivity, ferromagnetic or catalyst properties.

16. The process of claim 12 wherein said substrate is in a form selected from the group consisting of spheres, extrudates, flakes, fibers, fiber rovings, chopped fibers, fiber mats, rings, porous substrates, irregularly shaped particles and multi-channel monoliths.

17. An electrically conductive or ferromagnetic three- dimensional article produced in accordance with Claim 1.

18. An electrically conductive or ferromagnetic three- dimensional article produced in accordance with Claim 11.

19. A composition comprising a three-dimensional inorganic substrate having external and shielded surfaces and an electrically conductive or ferromagnetic transition metal oxide-containing coating on at least a portion of (a) all three-dimensions thereof, and (b) said shielded surfaces said coated substrate being adapted for use, alone or in combination with one or more articles or elements selected from the group consisting of an inorganic matrix element, an organic matrix element, a porous polymer matrix element, a porous inorganic matrix element, a fluid matrix element, a structural element, a catalyst component element, a porous membrane element, an electrostatic dissipation element, an electromagnetic interference shielding element, a resistance heating element or a mechanical electrical element.