EP0725698A4 - Acid assisted cold welding and intermetallic formation and dental applications thereof - Google Patents
Acid assisted cold welding and intermetallic formation and dental applications thereofInfo
- Publication number
- EP0725698A4 EP0725698A4 EP94930610A EP94930610A EP0725698A4 EP 0725698 A4 EP0725698 A4 EP 0725698A4 EP 94930610 A EP94930610 A EP 94930610A EP 94930610 A EP94930610 A EP 94930610A EP 0725698 A4 EP0725698 A4 EP 0725698A4
- Authority
- EP
- European Patent Office
- Prior art keywords
- process according
- acid
- metal
- powder
- metallic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
- B22F3/225—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip by injection molding
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
- A61K6/84—Preparations for artificial teeth, for filling teeth or for capping teeth comprising metals or alloys
- A61K6/842—Rare earth metals
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K6/00—Preparations for dentistry
- A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
- A61K6/84—Preparations for artificial teeth, for filling teeth or for capping teeth comprising metals or alloys
- A61K6/844—Noble metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/14—Treatment of metallic powder
- B22F1/145—Chemical treatment, e.g. passivation or decarburisation
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/10—Alloys containing non-metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
- C22C47/14—Making alloys containing metallic or non-metallic fibres or filaments by powder metallurgy, i.e. by processing mixtures of metal powder and fibres or filaments
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
Definitions
- the invention relates to a process of consolidating metallic and intermetallic composite materials and a process of forming bulk intermetallics at ambient temperatures.
- the invention relates to processes for forming the metallic composite materials as in situ dental restorations, high temperature materials, copper-tungsten and similar materials for thermal management, aluminide ⁇ such as nickel aluminides, nickel titanium alloys for shape memory effects applications and titanium nickel tin alloys.
- Powder metallurgy is a processing technique whereby very small diameter powder particles are compressed into parts or shapes by a number of methods that include vacuum hot pressing, hot isostatic pressing (HIP), sinter hipping, hot forging, etc. These processes require the sequential or simultaneous application of high temperature and pressure.
- the temperatures used in powder metallurgy are at an appreciable fraction of the melting point (T m ) of the compressed elements or alloys, usually above 0.8 T m .
- T m melting point
- the pressures applied are often near or beyond the yield point of the metals involved.
- consolidation is often done by hot roll bonding.
- Powder metallurgy is useful as an alternative to comelting appropriate amounts of metal constituent components in forming intermetallic compounds.
- ntermetallic compounds have a great potential for a variety of applications as a result of their specific properties such as hardness, high elastic moduli and oxidation resistance.
- the inherent brittleness of intermetallic compounds severely curtails their use in conventional thermomechanical processing operations to form net shapes.
- powder technology is often used for processing intermetallic compounds. The starting materials for this approach are pre-alloyed compounds that have been comminuted by various methods into powder particles.
- Intermetallic compound formation by interdiffusion of the constituent elements or extremely finely divided multi-phase solid formation by non-compound forming and non-interdiffusing elements is favored when the starting materials are in the form of a very small size particle powder.
- Such powders possess a large specific surface area, and hence, when mixed, form a relatively large interface area between the different constituents.
- the generation of an interface area between the different constituents depends on the efficiency of the mixing technique and also on the nature and properties of the mixed powder particles.
- Several mixing techniques are commonly used in order to maximize the contact points (interface area) between particles of different kinds. If the effect of particle properties on the outcome of the mixing process is neglected, prolonged mixing will tend to maximize the number of contact points between different particles by striving towards a random distribution of the particles of different kind.
- Ball milling is another technique that is used for mixing and also for reducing particle size.
- An extension of ball-milling is the mechanical alloying technique that yields alloyed powder products from elemental powder mixtures. Alloy or compound formation by ball milling is dependent on the kinetic energy input due to the rapidly rotating hard balls impinging on the powder particles. Thus ball-milling leads to high local temperature increases.
- Intermetallic compound formation at the interface of two metals in intimate contact is a documented phenomenon. In some instances, the formation of intermetallic compounds is beneficial, in others, its effects may be detrimental.
- the formation of a new compound at temperatures below the melting point of the metals in contact relies on interdiffusion effects in the solid state. In most binary combinations, ambient temperature is well below the melting temperature of the constituent metals and, consequently, little or no compound formation takes place at the interface. Notable exceptions to this are diffusion couples in which one of the constituent metals, e.g. mercury or gallium, has a low melting point, below or close to room temperature.
- Another important group of binary combinations which shows room temperature compound formation consists of a group I-B of the periodic table (Cu, Ag or Au) metal juxtaposed to a group III-A or IV-A (In, Sn or Pb) element.
- group III-A or IV-A In, Sn or Pb
- K.N.Tu et al. Jap. J. APPI. Phvs. SUPPI.. Pt.l, 633 (1974) .
- room temperature compound formation in these systems is related to fast diffusion behavior of the noble or near noble component (the I-B elements) in the matrices of the group III-A or IV-A metals.
- a Gd matrix is taken as a prototype for lanthanide elements, as one of the two components of a binary combination.
- Uranium matrix is taken as a prototype for other actmide elements, as one of the two components of a binary combination.
- Fast diffusion effects are not restricted to the above- mentioned systems.
- Other notable and relevant systems are combinations of an early transition metal element from the Group III-B (Sc, Y or a lanthanide element, Th and U) or from Group IV- B, (Ti, Zr or Hf) with a late transition metal from Group VIII (Fe, Co, Ni, Pd or Pt) .
- Fast diffusion of the small size late transition metal elements in the matrix of the early transition metal elements has been reported in the literature. In these latter systems, however, none of the constituent elements has a melting point even relatively close to room temperature. Thus, in spite of fast interdiffusion, some exposure to intermediate temperatures is necessary in order to achieve any significant intermetallic compound formation within a reasonable time frame.
- intermetallic compounds in even a relatively simple system such as two juxtaposed thin films, is a complex process. It depends on a number of variables such as the relative thickness of the individual initial layers, the diffusion mechanisms and the diffusivities of the atomic species in the different layers being formed, the nucleation characteristics of the various compounds, to mention just a few of the relevant parameters. It is not surprising, therefore, that in spite of the relatively large number of completed studies, no clear picture emerges regarding the outcome of the interdiffusion process in a thin film couple.
- the thin film configuration even though allowing an increase in the relative amount of compound to be formed at the interface, does not lend itself to the formation of bulk intermetallic compounds.
- Bulk formation of intermetallic compounds may be of both theoretical as well as practical interest. Bulk formation at room temperature and ambient pressure is of interest if extraneous constraints preclude the use of conventional processing and production methods, i.e. casting from the melt or diffusion assisted formation at elevated temperatures.
- Dental amalgams are metallic composites resulting from a reaction between mercury and various pre-alloyed silver-tin-copper alloys. The mixing of mercury, which is liquid at ambient temperature, with the alloy in powder form takes place immediately prior to insertion in the dental cavity. The mixture, compacted into the cavity with dental instruments, consolidates into a cohesive solid and hardens over a length of time. Dental amalgams are much harder than pure gold fillings, they display relatively high compressive strength but are brittle and possess low transverse-rupture strength.
- U.S. Patent No. 4,664,855 discloses a universally employed process that triturates elemental metals or intermetallic alloys, in the form of comminuted filings or atomized spherical powders, with the sintering agent mercury and compacts the resulting amalgam into a uniform, consolidated metallic composite.
- the process may be considered a combination of liquid phase and reactive metal sintering.
- the finely comminuted metallic or intermetallic powders react with the Hg and when pressure is applied to the reaction product, form a compact, high density mass.
- 3,933,961 discloses a process for preparing a pre-weighed alloy tablet of uniform weight that is then triturated with a weighed quantity of Hg to form a traditional amalgam alloy.
- the mercury content of dental amalgams has been a recurring source of concern because of the health and environmental hazards associated with its presence.
- Many aspects involved in the use of dental amalgams such as the various hazards, the possible substitute materials, their advantages and drawbacks, the economical considerations that are involved have been reviewed and discussed extensively in various publications as for example: Effects and Side-effects of Dental Restorative Materials", Adv. in Dental Res. 6:, Sept. 1992; JADA Vol. 122, Aug. 1991, papers p.54- 61, p.63-65, p.67-71, p.73-77; JADA Vol. 125. April 1994, papers p. 381-387, p. 392-399).
- Gold either in the form of foils, powder or pellets can be used instead of mercury containing dental amalgams in direct filling.
- pure gold Prior to its condensation, pure gold, in all its forms, has to undergo a degassing procedure to desorb any adsorbed layers that might impede or prevent consolidation into a cohesive solid. Degassing is achieved by exposing the filling material to elevated temperature just before its insertion in the dental cavity. Clean gold surfaces and other noble metal surfaces, devoid of adsorbed layers, cold-weld under moderate pressure to form cohesive solids. Pure gold fillings are malleable and ductile and display high values of transverse rupture strength but low values of hardness and compressive strength.
- One of the objectives of the present disclosure is to present a novel approach to low temperature compound formation in large quantities, using a method which takes advantage of the interdiffusion processes occurring at relatively low temperatures and ambient pressure.
- this invention pertains to a metallic composite restorative material formed from a mixture of elemental metals, alloys and/or intermetallic compounds that have been given an appropriate surface treatment.
- the invention further pertains to a process for preparing the metallic composite by compacting the surface treated mixture of elemental metal powders, without adding a liquid metallic agent, such as mercury, to form a solid, cohesive metallic composite body, in situ. Compaction can be performed at ambient temperature, below the melting points of the surface treated powders present in the mixture, under pressure sufficient to form a uniform metallic composite.
- the present inventors believe that the invention rests on several physical principles and specific findings that can be briefly described as follows: i) Cold-welding takes place across appropriately treated metal surfaces, from which oxide or adsorbed gas layers have been removed.
- the present invention comprises treating the metal surfaces by immersion in reducing agent such as a mild or dilute acid to efficiently surface clean a noble metal (e.g. silver) .
- reducing agent such as a mild or dilute acid
- Acid assisted consolidation of silver particles takes place at room temperature under moderate pressure to yield cohesive solids.
- the present inventors have found that intermetallic compound particles or metal particles other than a noble metal, when coated with an external noble metal, or more noble metal layer readily undergo acid-assisted consolidation.
- Noble metals are metals, as for example, silver, gold, platinum and palladium, which do not readily oxidize in air. Thus, more noble metals are those metals which have a more positive Standard Reduction Potential (SRP) in the electrochemical series (Handbook of Chemistry and Physics, page D-155, 61st Ed., 1980-81) .
- SRP Standard Reduction Potential
- Metallic composite materials can be prepared from powder mixtures that include a soft ductile component, preferably a noble metal, e.g. silver, and hard intermetallic compound components that have been coated with a noble metal such as for example silver. Acid-assisted consolidation of such mixtures yields composites whose mechanical properties depend on the ratio of the soft to hard component.
- (iii) Bulk quantities of intermetallic compounds can be prepared at ambient temperature if the interface area between the two metal components that interdiffuse is sufficiently large.
- a coating process as for example, but not limited to, electrolytic deposition from a fluidized bed, physical deposition processes and an immersion deposition process whereby a more noble metal, e.g. silver, deposits from a solution in which a less noble metal, e.g. tin, has been immersed in the form of solid powder particles.
- a huge interface area between the more noble and less noble component equal to the surface area of the less noble
- the metallic composites prepared by making use of the above are useful as dental restorative materials, specifically as mercury-free alternatives to dental amalgams.
- this invention pertains to 1) the synthesis of bulk quantities of intermetallic compounds (A B n ) , 2) the synthesis of finely dispersed two-phase alloys and 3) synthesis of metallic matrix composites (MMC) at temperatures significantly lower than the melting temperature of the constituent elements, 4) application of immersion coated metallic powders to synthesize composites, 5) application of fast interdiffusion couples to promot e compound f ormat ion making us e o f ac id as s isted consolidation techniques .
- intermetallic compounds A B n
- MMC metallic matrix composites
- Fig. 1 shows values of transverse rupture strength of consolidated silver powders.
- the figure shows the effect of the compression pressure and the significant increase in rupture strength achieved by acid-assisted consolidation (AAC) .
- Fig. 2 shows the effect of the acid concentration on the density and compressive strength of silver powders that have undergone acid-assisted consolidation by impact.
- Fig. 3 shows two superimposed x-ray diffraction spectra of a sample prepared according to the procedure described in Example 2. These spectra illustrate the compound formation at ambient temperature.
- Figs. 4 are x-ray diffraction spectra of a consolidated sample of Ag-coated Sn powder (Example 3) taken at different times after consolidation. Spectrum 4a was started 30 min after consolidation, spectrum 4b was taken 8 days later and spectrum 4c,
- Fig. 5 is a micrograph of a hand consolidated sample described in Example 3, the white areas represent the residual Sn, the gray areas the intermetallic compound formed at the Sn-Ag interface.
- Figs. 6 are x-ray diffraction patterns of a Ag-coated nearly stoichiometric Ag3Sn powder (Example 4) taken at different times after consolidation. Spectrum 6a was taken after consolidation, spectrum 6b, 64 h later. The sample was kept at 37 °C.
- Fig. 7 is a micrograph of the sample described in Example 4, the white areas represent excess Ag, the gray areas represent mainly initial spherical intermetallic compound particles and also the additional compound formed at the Ag-Ag ⁇ Sn interface.
- Figs. 8 are x-ray diffraction patterns of a consolidated Ag- coated atomized Ag-Sn alloy powder sample (Example 5) .
- the initial composition of the alloy was 60 wt. % Ag and 40 wt. % Sn, namely a two phase, Ag ⁇ Sn and Sn alloy.
- Spectrum 8a was taken 19 h after consolidation and spectrum 8b, 119 h later.
- Fig. 9 is a micrograph of the sample described in Example 5, the white areas represent excess Ag, the gray areas represent mainly initial spherical intermetallic compound particles and also additional compound formed at the Ag-Ag3Sn interface.
- Fig. 10 are diffraction patterns of a consolidated Ag-coated atomized Ag-Sn alloy powder sample, similar to that described in Example 6, but coated by a different chemistry.
- Fig. 11 is a micrograph of the sample prepared according to the method described in Example 6 that yields silver-coated Ag3Sn particles. There is continuous bright Ag coating surrounding each, (mostly spherical), well defined Ag-Sn alloy particles. The black dots are etch pits located at the excess free Sn sites. Some pores are also visible at the junction points of several particles.
- Fig. 12 is a micrograph of a consolidated, atomized composite dental alloy, consisting of Ag-coated, atomized Ag3S particles, atomized Cu-Ag alloy particles embedded in a matrix consisting of free Ag particles (Example 7).
- Fig. 13 shows the diffraction patterns of a consolidated mixture of indium particles immersion coated with silver (Example 8) .
- Fig. 14 shows diffraction patterns of a consolidated mixture of tin particles immersion coated with gold (Example 9).
- the sample consists essentially of the ⁇ - AuSn compound, a small fraction of AuSn2, the ⁇ -phase, and some excess Au.
- Fig. 15 is an optical micrograph of a Cu-W bi-phase composite, consolidated under dilute fluoroboric acid as described in Example 10.
- Fig. 16 is a low magnification scanning electron micrograph of a cross section of a tooth containing a filling consisting of a mixture of electrolytically silver-coated Ag4Sn that had been mixed with elemental silver and elemental tin particles and immersion coated with silver. This mixture was hand-consolidated with conventional dental instruments.
- Fig. 17 is an optical micrograph of the dentin-filling interface of the filling shown in Fig. 16.
- Fig. 18 are photographs of a dental filling with material prepared according to the present invention.
- the present invention pertains to a process for forming metallic restorative metallic composites or alloys which circumvents the need for a metallic liquid sintering agent such as mercury, indium, or gallium or other low melting-point metallic alloys and relies on an alternative to the so-called amalgamation process or to the gold filling process.
- a metallic liquid sintering agent such as mercury, indium, or gallium or other low melting-point metallic alloys
- This process relies on a combination of liquid acid assisted consolidation and fast diffusion effects that take place in some metals and their alloys.
- Liquid acid assisted consolidation enables cold-welding of loose powder particles, foils or sheets under moderate pressure at ambient temperature into a cohesive solid.
- the present inventors have found that such cold-welding, that takes place across particle surfaces that are in contact, can be made possible by appropriately surface treating the particles as an alternative to traditional high temperature exposure, commonly used to cold- weld gold surfaces.
- noble metals e.g., silver, gold, palladium and copper, cold-weld after having undergone suitable surface treatment by immersing the metal provided in particles, foils or sheets in a reducing media based on water, alcohol or oil that has the property of removing surface oxides.
- Preferred reducing media include mild or dilute acids, in order to remove the surface oxide layers.
- Suitable acids for use in the surface treatment according to this invention include, but are not limited to organic acids such as for example acetic acid or inorganic acids, as for example, fluoroboric acid, sulfuric acid, hydrofluoric acid, hydrochloric acid, sodium asorbate, potassium asorbate, citric acid, adipic acid, ascorbic acid, sulfamic acid with or without ammonium bifluoride and nitric acid.
- Suitable concentration for the acid for use in the invention are from about 1% to about 30%.
- the nature and concentration of the reducing media depends on the nature of the application. For example, in dental applications, fluoroboric acid is preferred in concentrations ranging from about 2 to about 10% by volume, with about 2.5% by volume being most preferred.
- the surface treatment essentially an electrochemical treatment, which can be carried out at about ambient temperature, comprises thorough cleaning of particulate, metal or pre-alloyed intermetallic compound, and removal of the surface oxide layers by immersion in the acid solution.
- Oxides on particles can also be, for example, electrolytically reduced even in oxidizing solutions by applying a negative potential.
- solutions containing sulfate can be used to reduce the oxide on iron by applying a negative potential even though the oxide will reform once the potential (voltage) is removed.
- the present invention further pertains to a process based on the aforementioned embodiment wherein non-noble metals, as for example, but not limited to, Ga, In, Ir, La, Re, Rh, Ru, Sn, Ti, Y, Zn, Nb, Mo, Ta, Sc, Hf, Th, Ce, Pr, Nd, Sm, Gd, TB, Gy, Ho, Er, Tm, Yb or Lu; or intermetallic compound particles are cold-welded by providing them with an external oxide-replacing metal coating of a more noble metal, as for example such as Ag, Au, Pd, Fe, Ni, Cu, Co or Pt.
- a more noble metal as for example such as Ag, Au, Pd, Fe, Ni, Cu, Co or Pt.
- the process comprises immersing the non-noble metals or intermetallic compound particles in a solution containing an electrolyte.
- the electrolyte is for example, but not limited to, at least one sulfamate, iodide, cyanate, nitrate, pyrophosphate, fluoroborate or sulfide salt of the oxide-replacing (more noble) metal.
- An electrolytic or coating process is conducted or replacement reactions are allowed to form the coating and subsequently separating by filtration, centrifuge, evaporation or other suitable means, the coated powder from the electrolyte solution. The coated powder is then cleaned, rinsed and immersed in a liquid acid solution and consolidated into a cohesive solid.
- the particles are coated in order to ensure that each particle has an external surface from which any oxide layer can be removed efficiently so that it readily undergoes cold-welding under moderate pressure. Contrary to known "cold-welding" of gold fillings discussed in the background above, no exposure to high temperature is required prior to consolidation of the coated particles.
- gas plasmas with inert and reducing atmospheres such as the forming gas (5% hydrogen and 95% nitrogen)
- the forming gas 5% hydrogen and 95% nitrogen
- vapor deposition, sputtering or mechanical plating will coat the powder particles with protective layers of Ag, Au or a related alloy which has non-tenacious oxides.
- the powders, foils and sheets may be subjected to a cathodic and/or anodic treatment which is followed by an acid treatment.
- the thus treated wet powders, foils and sheets are consolidated into a net shape.
- the cathodic and/or anodic treatment may be in combination with a rinsing step or may be eliminated in certain circumstances.
- there may be an optimal concentration of the acid Preliminary results are shown in Fig. 2, wherein the density and the strength are measured in compression as a function of the acid concentration.
- the liquid present between the suitably coated powder particles seeps out from between the particles ( foils or sheets) during the acid assisted consolidation.
- the liquid provides a very important secondary benefit in that very small powder particles are constrained under the surface of the liquid so that they can be handled more safely.
- Another benefit of the liquid is lubrication of the compressed particles.
- the "non-amalgamation" process described herein relies on fast-diffusion effects that take place in some metallic systems. Fast-diffusion as discussed above, is attributed to the ability of some diffusing species to penetrate interstitially into a host matrix. Diffusion takes place via an interstitial mechanism instead of the usual vacancy mechanism characteristic of diffusion in most metal systems.
- the fast-diffusing species are small-size, low-valence constituents (e.g., Ag) which diffuse rapidly within the host matrix of a large-size, usually high valence component (e.g. Sn) .
- a large-size, usually high valence component e.g. Sn
- mono-valent metals e.g., Cu, Ag and Au
- transition metals e.g., Fe, Co, Ni and Pd
- Group IV-B metals Sn, Pb
- Group III-B metals e.g., Y, La, Ti and Zr
- Y, La, Ti and Zr early transition metals
- the intermetallic compounds Ag3Sn and Ag Sn may be prepared by interdiffusion of silver and tin. Silver will diffuse rapidly into tin and also tin into silver (via grain- boundaries) , until the respective solubility levels, (of silver in tin and tin in silver) are reached. At the solubility limit, the intermetallic compounds Ag3Sn and Ag4Sn form.
- the amount of intermetallic compound that forms at the interface of mixed powders depends on the contact area between the tin and silver particles.
- the amount of intermetallic compound formed near that interface at about body temperature, preferably about 37°C, is limited. Typically, the amount of intermetallic formed does not exceed the layer width of the interface region of about 0.5 to 1 ⁇ m.
- comminuted amounts of Ag4Sn and/or Ag3Sn may be preferably added to an initial mixture of silver and possibly tin.
- the resulting initial mixture preferably consists of a certain weight fraction of the intermetallic compound with elemental silver, and/or silver based alloys. Elemental tin may also be added to the initial mixture.
- the relative fraction of the powdered, pre-alloyed intermetallic Ag3Sn and /or Ag3Sn in the mixture may preferably range from 0 to 70 percent.
- the properties of the consolidated material are determined by the properties of the starting materials incorporated into the mixture, by the relative amount of each component, by the surface treatment applied and by the details of the consolidation procedure that was used.
- increasing values of pressure applied for consolidation increase the density, compressive strength and rupture strength of the final product.
- the condensability namely its propensity to transform from a loose powder or slurry into a cohesive solid, and the transverse rupture strength are increased by increasing the unalloyed metal, e.g. silver, content of the mixture.
- Increased levels of hardness and compressive strength can be attained by incorporating into the mixture fractions of pre-alloyed intermetallic compounds which, in general, are much harder than the unalloyed metals.
- These compound particles can be spherical or lathe cut pre-alloyed silver-tin intermetallic compounds, for example, with various additions of other alloying elements. Pre-alloyed intermetallic compounds containing other components can also be considered.
- non-metallic hard compounds such as oxide, carbide or nitride particles in the form of high-strength structural whisker, particulate or fiber additives can also be incorporated in the mixture. Such additives may include, but are not limited to, alumina powder, silicon carbide powder, graphite, diamond, sapphire, or the like. Other whisker, fiber or particle additives are within the scope of the invention.
- a hard intermetallic compound fraction can be formed in-situ within the consolidated mixture. In-situ formation implies compound formation of bulk quantities of intermetallic compounds, as previously described, after the mixing of the powder components has taken place.
- Metal combinations which give rise to intermetallic compound formation include, but are not limited to, members of the group consisting of Au, Ag, Fe, Pt, Pd, Ni, Co and Cu as a first component in combination with a member selected from the group consisting of Ga, In, Ir, La, Re, Rh, Ru, Sn, Ti, Y, Zn, Nb, Mo, Ta, Sc, Hf, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Tb, Lu, U, Th and W.
- a preferred metal combination that gives rise to intermetallic compound formation contains a first elemental metal, Sn, and a second elemental metal, Ag.
- a preferred Ag:Sn ratio of the two metals is from 4:1 to about 3:2. More preferably, the Ag:Sn ratio is from 4:1 to 3:1.
- the particles be provided with an external coating that is prone to cold-welding.
- this coating should be a more noble or noble metal, e.g., silver coating.
- silver surfaces readily undergo acid assisted consolidation.
- the external surface coating can be provided by any technique for surface coating of powder particles. These include coatings from a gaseous or from a liquid phase. Gaseous coatings include but are not limited to fluidized bed, vacuum evaporation, sputtering, plasma assisted and other techniques.
- Coatings from a liquid phase include but are not limited to electrolytic, as for example electrolytic coating from a fluidized bed onto particle or fibers; immersion or substitution deposition.
- electrolytic as for example electrolytic coating from a fluidized bed onto particle or fibers; immersion or substitution deposition.
- One example of a fluidized bed coating technique is described in a copending application of some of the present inventors entitled “Electrochemical Fluidized Bed Coating of Powders", hereby incorporated herein in its entirety by reference, filed concurently herewith and having Attorney Docket No. 53917.
- Fig. 12 represents a silver-coated Ag3Sn powder mixed with elemental Ag, Sn and atomized Cu-Ag alloy particles and then consolidated.
- the Ag3Sn particles have a thin Ag coating.
- the silver-coated Ag3Sn particles bond well to the free Ag particles which make up most of the Ag matrix.
- the atomized Cu-Ag particles provide increased hardness to the material.
- a consolidated composite solid body such as a dental restoration may be formed, in situ (e.g., in a dental cavity or mold for a commercial press), by compacting the wet surface treated mixture of the oxide-free and coated powders, without adding any metallic liquid sintering agent.
- compacting include, but are not limited to, die press and sinter, roll bonding, extrusion, "hipping" (hot isostatic pressing), "hot pressing or cold pressing", or compacting with normal or modified dental instruments in situ in a patient's mouth.
- Immersion or substitution deposition of silver or gold is an extremely useful method, in the context of the present invention, in order to provide a very finely dispersed deposit of silver or gold.
- a metallic powder consisting either of elemental metal, alloy or intermetallic compound particles, is immersed in a aqueous solution of a more noble metal.
- the less noble metal constituents of the immersed solid powder undergo partial oxidative dissolution in the solution, concurrently with the reduction and deposition of the more noble metal from the solution.
- This method allows the creation of a large interface area between the residual, partly dissolved solid particles and the more noble, metallic deposit from the solution.
- the advantages of this method of deposition of the noble metals silver or gold are twofold.
- a pure silver or gold deposit is provided uniformly through the mixture. Such a deposit will provide the required interface material that readily cold-welds by acid assisted consolidation.
- the initial solid particles after their partial oxidative dissolution, still contain metallic elements which are defined as appropriate host metal for fast diffusion, e.g., Sn, the conditions for the formation of intermetallic compounds by fast interdiffusion are met.
- this method provides a mixture of powders, i.e. the initial solid powder e.g., Sn-containing particles coated with the fine Ag deposit, that displays a large Sn-Ag interface area. Maximum interface area will, of course, be achieved by having each individual tin (or tin-containing compound) particle coated by a silver layer.
- Example 3 A high compound content of the product, prepared according to this approach, is shown in Examples 3, 5, 6 and 7.
- the powder particles were provided with a silver environment by having the silver deposit from the solution.
- the particles are pure Sn particles
- Examples 5, 6 and 7 they are silver-tin compound particles with about 18 wt. % free tin content.
- the diffraction patterns taken after different time intervals after the samples had been consolidated show an appreciable increase of the compound Ag4S +Ag3Sn fraction in the final sample.
- Example 4 in which a nominally stoichiometric compound was silver coated, an increase of the compound content was observed after the sample had been kept at 37° C for 64 h. In this case, in spite of the nominal stoichiometric composition, the free Sn (which originated from the fast cooling of the atomized powder) reacted with silver and yielded some additional Ag4Sn+Ag3Sn compound fraction.
- Compound formation by this method is not limited to powders in which a large Ag-Sn interface is created.
- Example 8 illustrates compound formation in the Ag-In system
- Example 9 illustrates compound formation in Au-Sn systems
- Example 12 illustrates compound formation in Cu-Sn systems, respectively.
- an in situ dental restoration is a preferred application of the compacted alloy thus formed.
- commercially available amalgam powder packages may be surface treated according to the process of the invention, mixed with appropriate other powders and subsequently compacted to form a consolidated alloy.
- These commercially available powders may typically consist of combinations of intermetallics which may contain copper and/or zinc (these intermetallics typically approximate the Ag3Sn compound) .
- Ag and pre- alloyed intermetallic compounds at or close to the Ag3Sn composition coated with silver or gold are compacted at body temperature.
- elemental tin powder, silver-coated is mixed with silver and/or silver-copper alloy powder particles and compacted at body temperature.
- a preferred coated powder used in dental applications is Ag3Sn and/or Ag4Sn and a preferred elemental powder is Ag, with a preferred overall Ag:Sn atomic ratio ranging from 3:1 to about 8:1.
- Pre-alloyed intermetallics subsequently combined with elemental silver and/or tin particles, may consist of a compound having a weight ratio of Ag:Sn ranging from about 5:1 to about 3:1. In these compounds an excess tin may be locally present. This excess can be compensated for by increasing a weight ratio of the elemental silver to intermetallic compound.
- the in situ formation of the alloy preferably occurs at a temperature below the melting point of the coated powders and under an applied pressure.
- Exemplary ranges of temperature and pressures under which the alloys may be formed include, but are not limited to, from 20 °C to about 100 °C, and from 20 MPa to about 400 MPa, respectively.
- a preferred temperature for the consolidation of the composite for dental restorative purposes is about body temperature.
- a preferred pressure is about 200 MPa or approximately the pressure exerted by ordinary dental tools.
- Intermetallic compounds of the invention may have exemplary equiaxial particle sizes ranging from 0.5 ⁇ m to about 100 ⁇ m.
- the particle sizes of the powders range from about 0.5 ⁇ m to about 40 ⁇ m.
- Space-filling is improved by having multi-modal particle size distributions.
- the mixture should consist of particles in the 30 to 40 ⁇ m size range admixed with particles in the 2 to 10 ⁇ m size range.
- the process can be applied to systems in which neither solid solutions nor intermetallic compounds are formed.
- An alloy consisting of two such metals will display a mixture of two phases, associated with the two components. The homogeneity of such a mixture will depend on the initial particle size and the conditions under which mixing was carried out. In many instances the properties of such alloys follow the rule of mixtures law and scale with the respective concentration of the components.
- An immersion coating process can be taken advantage of in order to ensure a homogeneous distribution of the two components at a scale which is determined by the particle size of the component that is added in the form of powder to the solution.
- physical and electronic properties can be engineered as for example, thermal diffusivity, thermal conductivity, the coefficient of thermal expansion, magnetic properties and electronic properties can be custom-tailored to specific situations by using the process according to the present invention.
- Engineering properties of coated particles by controlling the relative volume fractions of the particulate material and the coating material is described in a copending patent application of one of the present inventors (U.S. Patent Application No. 08/102,532, filed August 4, 1993, which is a continuation of 07/731,809 filed July 17, 1991), entitled “Methods of Manufacturing Particles and Articles Having Engineered Properties and Applying Coatings Having Engineered Properties to Articles", hereby incorporated herein in its entirety by reference.
- the previously described immersion or substitution deposition of metals is used to form the uniform and fine distribution of the two components.
- the electrolyte containing the more noble component has to be able to dissolve the less noble component initially immersed as a solid and also to dissolve any protecting oxide layer present on its surface.
- Such binary combinations display immiscibility of their components up to 1000°C.
- the less noble metal is one of the group that includes the metals Nb, Mo, Ta and W, while the more noble component is a metal that belongs to the group Cu, Ag and Au.
- Example 10 i.e. the Cu-W system, illustrates one of these combinations.
- Table III displays representative examples of combinations of binary systems which display immiscibility of their components (at at least 1000 * C) and which can be prepared according to this invention.
- composition of the product material is pre- determined.
- the composition of compound-forming coated powders determines the structure, and hence the properties of the resulting compound. Pre-determining the composition of two-phase alloys or metal matrix composites, allows the custom-design of materials with desired properties or combination of properties.
- the product material i.e., the intermetallic compounds, two-phase alloys or metal matrix composites can be formed into near-net shape parts.
- the product material i.e., the intermetallic compounds, two-phase alloys or metal matrix composites
- Examples of various methods of preparation of powder mixtures that can be transformed into bulk intermetallic compounds at near ambient temperature and under moderate pressure are described in the following non-limiting Examples 2 to 12.
- Most examples (2 to 7) are concerned with the Ag-Sn system which is considered as the paradigm system for applications as dental restorative materials.
- An actual typodont filled with a restorative material prepared according to the methods described hereby is shown in Fig. 16.
- FIG. 17 A higher magnification optical micrograph of the interface area between the dental filling material and tooth structure and illustrating the good bonding is shown in Fig. 17. Finally a photograph of an extracted tooth with a mercury-free filling prepared according to the above-described methods is shown in Fig. 18.
- Examples 8, 9, 11 and 12 illustrate a more general aspect of the invention, wherein the inventive processes are applied to form bulk intermetallic compounds in additional systems.
- Example 10 illustrates the potential of applying some of the processes to non-compound forming systems in order to achieve homogeneous fine-scale mixtures of different phases.
- Silver powder is stirred for 5 min in a 10% HBF4 solution and consolidated in near-net-shape molds for density, compressive and transverse rupture strength determination.
- dry silver powder is also consolidated and its transverse rupture strength determined.
- the results are shown in Fig. 1 and illustrate significant increase of transverse rupture strength resulting from the surface treatment of the silver powder. This surface treatment increases the compressive and transverse rupture strength of both spherical and dendritic silver particulates.
- the density and the compressive strength of the consolidated silver as a function of the concentration used in the acid-assisted consolidation process is shown in Fig. 2.
- a solution of 12.10 g/L AgBF4 (Aldrich, Cat. No. 20,836-1) in 20 % HBF4 is prepared. 8.02 grams of Sn metal powder, 99.8 % pure, (-325 mesh, 12.5 ⁇ m average size from CERACTM, Cat. # T-1120), is added to the solution and stirred for 50 min. The powder is allowed to settle, the liquid removed and the remaining slurry is rinsed in a 10 % HBF4 solution. The powder is allowed to settle again and the slurry removed. A pellet is pressed from the slurry, at 1,178 MPa in a steel mold. X-ray diffraction analysis of this pellet started within 30 min of its preparation. The diffraction pattern that is obtained is shown in Figure 4a.
- Fig. 5 is a micrograph of a sample that had been hand consolidated using common dental office tools.
- the light areas represent the residual elemental Sn particles which are embedded in the gray matrix consisting of the intermetallic compound that was formed at the Sn-Ag interfaces.
- a solution of 20 g/1 of AgN ⁇ 3 in 10 % HBF4 was prepared.
- 6.1 g of atomized, average size 13.5 ⁇ m diameter Ag-Sn compound powder was added to and stirred in the solution at room temperature for 6 min.
- the nominal composition of the atomized Ag- Sn alloy was 73 weight % Ag and 27 weight % Sn corresponding to the Ag3Sn compound composition.
- the atomized spherical particles were not in a thermodynamic equilibrium state and contained some elemental Sn.
- the powder was allowed to settle in the liquid which was removed from above the slurry.
- the slurry was rinsed in a 10 % HBF4 solution and again the liquid removed.
- Fig. 6a shows approximately equal amounts of elemental Ag and of the Ag3Sn+Ag4Sn compounds and some traces of elemental Sn.
- Fig. 6b shows the diffraction spectrum of the same sample after 64 h at 37° C. This spectrum shows increased intensity of the diffraction lines corresponding to the compound, decrease of the Ag lines and almost complete disappearance of the diffraction lines of elemental Sn.
- Fig. 7 is a metallographic cross-section of a hand consolidated sample, showing a uniform dispersion of the dark gray
- a solution of 12 g/L AgBF4 (Aldrich, Cat. No. 20,836-1) in 20 % HBF4 was prepared.
- An amount of 6.1 grams of atomized Ag-Sn alloy powder was stirred in the solution, for 5 min.
- the powder was allowed to settle, the liquid removed and the remaining slurry rinsed in a 10 % HBF4 solution. Again the powder was allowed to settle and the slurry removed.
- a pellet was pressed at 1,178 MPa from that slurry in a steel mold.
- the metallography of a hand consolidated sample by common dental tools shows a structure similar to that shown in Fig. 5, but with a higher Ag/Ag3Sn ratio.
- the gray areas represent the original Ag-Sn alloy particles which are embedded in the bright matrix consisting mainly of silver and silver-rich tin solid solution.
- a solution of 265 g/L KI (potassium iodide, ALFA Cat. # 11601) and 10 g/L AgN03 (silver nitrate, ALFA Cat. # 11414) was prepared.
- 4.06 g of Ag-Sn atomized alloy powder (13.2 ⁇ m average size) were rinsed in 10 % HBF4, and stirred in the first solution for 32 min.
- Fig. 10a is the diffraction pattern of the initial Ag-Sn alloy, prior to coating, showing the presence of the intermetallic compound Ag4Sn+Ag3Sn and of elemental Sn.
- Fig. 11 is an optical micrograph of a pellet of that slurry, compressed at 470 MPa, illustrating the efficiency of the process, described in this example, in producing with a relatively low volume fraction of silver (represented by the bright circular halos, surrounding the spherical, atomized Ag-Sn alloy particles), large silver-silver interface area that promotes consolidation, and silver-tin interface that promotes compound formation.
- a silver coating solution was prepared by dissolving 265 g of KI (ACS, ALFA Cat. # 11601) and 10 g of AgN ⁇ 3 (ACS, ALFA Cat. # 11414, 99.94% pure) and 8 ml concentrated HCl (Mallinckrodt) in 1 L of distilled H2O at pH 1.06 after adjustment by 10 M KOH.
- An amount of 4 g atomized Ag(60)Sn(40) powder with 13.2 ⁇ m average particle size was stirred in 500 ml of 10% HBF4 solution for 30 sec. The acid was decanted and the wet powder rinsed in distilled H2O. The powder was stirred in 500 ml of the silver coating solution for 30 min.
- Fig. 12 is a metallography of the consolidated sample.
- the silver copper alloy component was added to increase the overall hardness of the consolidated solid.
- a solution of 21.7 g/L AgBF4 (Ag as metal 12 g) (Aldrich, Cat. No. 20,836-1) in 5 % HBF4 was prepared.
- An amount of 7 g of In metal powder, -400 mesh particle size, (ALFA, 99.99%, Cat. # 11024) was stirred for 8 min in 250 ml of the silver fluoroborate solution at a pH of 0.5 and 23°C temperature.
- the slurry, after decanting the solution, was rinsed in 10% HBF4 and consolidated at 300 MPa in a steel mold.
- curve (a) is the x-ray diffraction pattern of the resulting disc, obtained approximately lh after the removal of the slurry from the solution.
- Fig. 14 is a x-ray pattern of a disc made from the slurry that was removed from the solution consolidated at 1220 MPa. The x-ray exposure was made lh after the removal of the slurry from the solution. The sample consists mostly of the AuSn compound, a small fraction of AuSn2 and some excess Au.
- a solution of 29.4 g/L AgBF4 (16.2 g Ag as metal) (Aldrich, Cat. No. 20,836-1) in 5 % HBF4 was prepared.
- An amount of 3.15 g of In metal powder, -400 mesh particle size, (ALFA, 99.99%, Cat. # 11024) was stirred for 10 min in 250 ml of the silver fluoroborate solution at a pH of 0.5 and 23°C temperature.
- An x-ray pattern of the resulting disc was obtained approximately 2Oh after the removal of the slurry from the solution. Analysis of the pattern obtained shows that Ag is the main component with the additional presence of Agln 2 ( ⁇ phase) , Aggln4 ( ⁇ phase) , and Agin ( ⁇ phase) .
- the x-ray pattern after a 51 h anneal at 140 °C shows that Ag 9 ln 4 is the major constituent (75%) with Ag3ln (25%) and some residual Ag and traces of Agln2-
- Example 12 A solution of 708 g/L Cu(BF4)2 (Fidelity Chemical Products Corp. #0360) in 10 % HBF4 was prepared. Silver metal constituted 190 g of that amount of copper fluoroborate. An amount of 8 g of Sn metal powder, -325 mesh particle size, was stirred for 10 min in 100 ml of the copper added to 400 ml solution of 10% fluoroborate solution at a pH 0.2 and at 23°C temperature. The slurry, after decanting the solution, was rinsed in 10% HBF4 and consolidated at 300 MPa in a steel mold. X-ray exposure was made within 1 h after the removal of the slurry from the solution.
Abstract
Description
Claims
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13331693A | 1993-10-08 | 1993-10-08 | |
US133316 | 1993-10-08 | ||
US317729 | 1994-10-04 | ||
US08/317,729 US6001289A (en) | 1991-12-04 | 1994-10-04 | Acid assisted cold welding and intermetallic formation |
PCT/US1994/011312 WO1995010379A1 (en) | 1993-10-08 | 1994-10-05 | Acid assisted cold welding and intermetallic formation and dental applications thereof |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0725698A1 EP0725698A1 (en) | 1996-08-14 |
EP0725698A4 true EP0725698A4 (en) | 1999-05-26 |
Family
ID=26831256
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94930610A Withdrawn EP0725698A4 (en) | 1993-10-08 | 1994-10-05 | Acid assisted cold welding and intermetallic formation and dental applications thereof |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0725698A4 (en) |
JP (1) | JPH10501025A (en) |
AU (1) | AU691530B2 (en) |
CA (1) | CA2173734A1 (en) |
IL (1) | IL111195A (en) |
WO (1) | WO1995010379A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6001289A (en) | 1991-12-04 | 1999-12-14 | Materials Innovation, Inc. | Acid assisted cold welding and intermetallic formation |
JP6079375B2 (en) * | 2013-03-29 | 2017-02-15 | 三菱マテリアル株式会社 | Solder powder, method for producing the same, and solder paste using the powder |
CN106925774B (en) * | 2017-03-16 | 2019-06-07 | 重庆云天化瀚恩新材料开发有限公司 | A kind of preparation method of silver-coated copper powder |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3936577A (en) * | 1971-12-15 | 1976-02-03 | E. I. Du Pont De Nemours & Company | Method for concomitant particulate diamond deposition in electroless plating, and the product thereof |
US4477296A (en) * | 1982-09-30 | 1984-10-16 | E. I. Du Pont De Nemours And Company | Method for activating metal particles |
US5026519A (en) * | 1990-10-19 | 1991-06-25 | Gte Products Corporation | Method of making tungsten powder compacts |
WO1993010927A1 (en) * | 1991-12-04 | 1993-06-10 | THE UNITED STATES OF AMERICA, as represented by THE SECRETARY, UNITED STATES DEPARTMENT OF COMMERCE | Process for forming alloys in situ in absence of liquid-phase sintering |
Family Cites Families (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3914507A (en) * | 1970-03-20 | 1975-10-21 | Sherritt Gordon Mines Ltd | Method of preparing metal alloy coated composite powders |
US3871876A (en) * | 1974-03-18 | 1975-03-18 | Kamal Asgar | Dental Amalgam |
US4427501A (en) * | 1976-09-10 | 1984-01-24 | Rogers Olbert W | Method of manufacture of artificial teeth |
US4450188A (en) * | 1980-04-18 | 1984-05-22 | Shinroku Kawasumi | Process for the preparation of precious metal-coated particles |
JPS56150101A (en) * | 1980-04-18 | 1981-11-20 | Shinroku Kawakado | Preparation of powder coated with noble metal |
US4323395A (en) * | 1980-05-08 | 1982-04-06 | Li Chou H | Powder metallurgy process and product |
JPS5944378B2 (en) * | 1981-07-27 | 1984-10-29 | 株式会社東洋化学研究所 | Method for manufacturing dental silver amalgam alloy |
US4528207A (en) * | 1982-06-04 | 1985-07-09 | The University Of Virginia Alumni Patents Foundation | Plated dental amalgam alloys |
US4742861A (en) * | 1985-04-15 | 1988-05-10 | Itzhak Shoher | Method and material for dental structures |
US4664855A (en) * | 1985-11-12 | 1987-05-12 | Special Metals Corporation | Method for producing amalgamable alloy |
DE3717048C1 (en) * | 1987-05-21 | 1988-11-03 | Degussa | Process for the preparation of alloy powders for dental amalgams |
JPH01119611A (en) * | 1987-11-02 | 1989-05-11 | Dowa Mining Co Ltd | Production of metal powder |
JPH01119602A (en) * | 1987-11-02 | 1989-05-11 | Mitsui Mining & Smelting Co Ltd | Production of silver-coated copper powder |
DE3820970C1 (en) * | 1988-06-22 | 1989-11-09 | Degussa Ag, 6000 Frankfurt, De | |
MX170144B (en) * | 1988-09-12 | 1993-08-09 | Ampex | COATING COMPOSITIONS OF MAGNETIC METAL PARTICLES AND RECORDING MEDIA |
JPH02253837A (en) * | 1989-03-28 | 1990-10-12 | Agency Of Ind Science & Technol | Method for coating surface of inert granular matter |
JPH0689320B2 (en) * | 1989-06-28 | 1994-11-09 | 新日本製鐵株式会社 | Powder consisting of metal and polybasic acid |
JP2832247B2 (en) * | 1990-07-24 | 1998-12-09 | 三井金属鉱業株式会社 | Method for producing silver-coated copper powder |
JP3143684B2 (en) * | 1991-08-09 | 2001-03-07 | 奥野製薬工業株式会社 | Coating method of granular material and composite plating method by magnetic metal coating |
JPH05234729A (en) * | 1992-02-21 | 1993-09-10 | Nippon Steel Corp | Manufacture of rare earth-iron-nitrogen magnet powder and manufacture thereof |
-
1994
- 1994-10-05 WO PCT/US1994/011312 patent/WO1995010379A1/en not_active Application Discontinuation
- 1994-10-05 CA CA002173734A patent/CA2173734A1/en not_active Abandoned
- 1994-10-05 JP JP7511896A patent/JPH10501025A/en not_active Ceased
- 1994-10-05 AU AU79675/94A patent/AU691530B2/en not_active Ceased
- 1994-10-05 EP EP94930610A patent/EP0725698A4/en not_active Withdrawn
- 1994-10-07 IL IL11119594A patent/IL111195A/en not_active IP Right Cessation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3936577A (en) * | 1971-12-15 | 1976-02-03 | E. I. Du Pont De Nemours & Company | Method for concomitant particulate diamond deposition in electroless plating, and the product thereof |
US4477296A (en) * | 1982-09-30 | 1984-10-16 | E. I. Du Pont De Nemours And Company | Method for activating metal particles |
US5026519A (en) * | 1990-10-19 | 1991-06-25 | Gte Products Corporation | Method of making tungsten powder compacts |
WO1993010927A1 (en) * | 1991-12-04 | 1993-06-10 | THE UNITED STATES OF AMERICA, as represented by THE SECRETARY, UNITED STATES DEPARTMENT OF COMMERCE | Process for forming alloys in situ in absence of liquid-phase sintering |
Non-Patent Citations (3)
Title |
---|
DARIEL M P LASHMORE D S ET AL: "NEW TECHNOLOGY FOR MERCURY FREE METALLIC DENTAL RESTORATIVE ALLOYS", POWDER METALLURGY, vol. 37, no. 2, 1 January 1994 (1994-01-01), pages 88, XP000466702 * |
RATZKER M ET AL: "Ambient temperature synthesis of bulk intermetallics", INTERMETALLIC MATRIX COMPOSITES III SYMPOSIUM, INTERMETALLIC MATRIX COMPOSITES III, SAN FRANCISCO, CA, USA, 4-6 APRIL 1994, 4 March 1994 (1994-03-04), 1994, Philadelphia, PA, USA, Mater. Res. Soc, USA, pages 41 - 46, XP002098376 * |
See also references of WO9510379A1 * |
Also Published As
Publication number | Publication date |
---|---|
IL111195A0 (en) | 1995-03-30 |
WO1995010379A1 (en) | 1995-04-20 |
AU7967594A (en) | 1995-05-04 |
CA2173734A1 (en) | 1995-04-20 |
EP0725698A1 (en) | 1996-08-14 |
AU691530B2 (en) | 1998-05-21 |
IL111195A (en) | 1998-08-16 |
JPH10501025A (en) | 1998-01-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5711866A (en) | Acid assisted cold welding and intermetallic formation and dental applications thereof | |
US5318746A (en) | Process for forming alloys in situ in absence of liquid-phase sintering | |
US4762558A (en) | Production of reactive sintered nickel aluminide material | |
JPS60228602A (en) | Dispersion-enhanced metal composite body | |
US6042781A (en) | Ambient temperature method for increasing the green strength of parts | |
EP1044286A1 (en) | Dispersion hardening alloy and method for the production of the alloy | |
AU691530B2 (en) | Acid assisted cold welding and intermetallic formation and dental applications thereof | |
JPS62502813A (en) | New alloys with high electrical and mechanical properties, processes for their production and their use in particular in electrical, electronic and related fields | |
AU718126B2 (en) | Acid assisted cold welding and intermetallic formation and dental applications thereof | |
JP2001518143A (en) | Method of manufacturing parts from particulate ferrous material | |
JP2943026B2 (en) | Method for producing titanium-based alloy and titanium-based sintered alloy | |
JP3327080B2 (en) | High strength and high wear resistance diamond sintered body and method for producing the same | |
Dariel et al. | A silver-tin alternative to dental amalgams | |
JP3796321B2 (en) | Method for producing sintered material using tin-coated copper powder | |
Ratzker et al. | Ambient temperature synthesis of bulk intermetallics | |
JP2680832B2 (en) | Method for producing Cu-Zn-Al sintered superelastic alloy | |
JPH01275723A (en) | Manufacture of ni2al3 material having self-lubricative characteristics | |
JPH03247731A (en) | Ceramic-copper alloy composite | |
DE10047525B4 (en) | A method of producing a shaped article using a raw material containing silicon carbide in powder or particulate form and copper, and shaped articles thus produced | |
JPS63203733A (en) | Manufacture of shape memory alloy | |
JPS59226134A (en) | Manufacture of ti-ni alloy material | |
JPS63140049A (en) | Forming method for ti-al intermetallic compound member | |
Gennari | Strong Biocompatible Niobium Alloy Developed |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19960502 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: KELLEY, DAVID R. Inventor name: EICHMILLER, FREDERICK C. Inventor name: GIUSEPPETTI, ANTHONY A. Inventor name: RATZKER, MENAHEM B. Inventor name: JOHNSON, CHRISTIAN E. Inventor name: DARIEL, MOSHE P. Inventor name: LASHMORE, DAVID S. Inventor name: BEANE, GLENN L., R.F.D. 3 |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: BEANE, GLENN L. Owner name: THE UNITED STATES OF AMERICA, AS REPRESENTED BY T Owner name: MATERIALS INNOVATION INC. |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: BEANE, GLENN L. Owner name: THE UNITED STATES OF AMERICA, AS REPRESENTED BY T Owner name: MATERIALS INNOVATION INC. |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: KELLEY, DAVID R. Inventor name: EICHMILLER, FREDERICK C. Inventor name: GIUSEPPETTI, ANTHONY A. Inventor name: RATZKER, MENAHEM B. Inventor name: JOHNSON, CHRISTIAN E. Inventor name: DARIEL, MOSHE P. Inventor name: LASHMORE, DAVID S. Inventor name: BEANE, GLENN L., R.F.D. 3 |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: BEANE, GLENN L. Owner name: THE UNITED STATES OF AMERICA, AS REPRESENTED BY T Owner name: MATERIALS INNOVATION INC. |
|
A4 | Supplementary search report drawn up and despatched |
Effective date: 19990413 |
|
AK | Designated contracting states |
Kind code of ref document: A4 Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE |
|
17Q | First examination report despatched |
Effective date: 19991111 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20011120 |