EP1587772B1 - Method for producing porous sintered bodies - Google Patents

Method for producing porous sintered bodies Download PDF

Info

Publication number
EP1587772B1
EP1587772B1 EP04705030A EP04705030A EP1587772B1 EP 1587772 B1 EP1587772 B1 EP 1587772B1 EP 04705030 A EP04705030 A EP 04705030A EP 04705030 A EP04705030 A EP 04705030A EP 1587772 B1 EP1587772 B1 EP 1587772B1
Authority
EP
European Patent Office
Prior art keywords
molding composition
foaming
sintered
blowing agent
molding
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.)
Expired - Lifetime
Application number
EP04705030A
Other languages
German (de)
French (fr)
Other versions
EP1587772A1 (en
Inventor
Jörg FÄRBER
Manfred Jaeckel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plansee SE
Original Assignee
Plansee SE
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Plansee SE filed Critical Plansee SE
Publication of EP1587772A1 publication Critical patent/EP1587772A1/en
Application granted granted Critical
Publication of EP1587772B1 publication Critical patent/EP1587772B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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
    • B22F3/10—Sintering only
    • B22F3/11—Making porous workpieces or articles
    • B22F3/1121—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers
    • B22F3/1125—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers involving a foaming process
    • 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
    • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

  • the invention relates to a method for producing a cellular porous shaped sintered body with the manufacturing steps of preparing a thermoplastic flowable molding compound by mixing ceramic u / o metal powder with binder components and incorporation of organic blowing agents, converting the molding material into a molten state and introduction into a molding device, foaming the molding material by means of the blowing agent, solidification of the foamed molding composition, spreading of blowing agents and organic components and sintering of the thus treated molding.
  • a ductile binder has to be added to the matrix powder, for example a ductile metal powder in hard metal production, in order to obtain products which can be pressed and sintered.
  • a relatively recent technology for producing ceramic metallic sintered shaped bodies is the MIM (metal injection molding) process, in which the ceramic metallic matrix powder particles are mixed with organic binder components, and the mixture is usually brought into the desired shape in the thermoplastic state which solidifies molded part and then freed by pyrolysis u / o by dissolving and extracting its organic and / or inorganic binder components and finally sintered to form an approximately pore-free dense molded body.
  • the shaping takes place alternatively for injection molding, for example by means of extrusion.
  • Targeted pore structures in sintered bodies are created, for example, by mixing the matrix starting powders with a pulverulent placeholder, wherein the placeholder particles usually chemically before or during the sintering process from the molded composite material removed u / o removed by thermal decomposition and take their place free spaces, or pores. It is also known to produce pore structures in moldings by blowing in gases, for example argon or nitrogen gas, into a molten metal.
  • gases for example argon or nitrogen gas
  • sintered bodies having a pore structure are produced by introducing blowing agents as additives as homogeneously as possible into a matrix material mixed with thermoplastic binder and heating this composite or molding compound to the evaporation or foaming temperature of the blowing agent.
  • blowing agents as additives as homogeneously as possible into a matrix material mixed with thermoplastic binder
  • this composite or molding compound to the evaporation or foaming temperature of the blowing agent.
  • bubble-shaped gas spaces are formed in the, or foam formations of the thermoplastic or molten molding material, which stabilize upon cooling and transfer of the molding compound into a solid state and then allow extraction of the gas inclusions or the remaining propellant leaving pores.
  • the binder additives are extracted. The ready mechanical stabilization of the shaped body takes place by means of an additional sintering step.
  • a useful foaming agent is an isocyanate-capped polyoxyethylene polyol, which eliminates the need for an additional binder. According to one embodiment, under 50% volume expansion is foamed.
  • a disadvantage of this method is the use of water in conjunction with polyurethane or polyethylene binders, which allows the mass thus formed little thermoplastic properties and thus foaming in only a very limited volume. He comes to shrinkage after foaming.
  • the practically controllable pore content in the sintered body is 10-20% by volume, which generally precludes the formation of cellular pore structures.
  • the DE 177 15 20 A1 describes a method for producing ceramic masses by casting, with honeycomb structure in the mass inside and with a smooth surface, are stirred in the plastics with pearl structure in the tempered casting slurry and the molded body solidifies under cooling.
  • Preferred plastic is blowing agent-containing polystyrene which has been prefoamed depending on the desired bead size.
  • a disadvantage of this method is only unsatisfactory controllability of the bead distribution and arrangement in the casting slip, which is the use of the method with only moderate requirements for the mechanical minimum capacity of the cooled ceramic mass on the production of Shaped bodies with only low pore volume. The method does not provide for dispensing the polystyrene beads from the mass.
  • the essential features of the process lie in the separate preparation of two different components of a molding composition, on the one hand as an aqueous solution containing the foaming or blowing agent in a resinous binder and on the other hand, as a metal powder and a water-soluble, resinous binder solution , which are both brought together just before the planned foaming process.
  • the foaming step takes place in an atmosphere with at least 65% humidity.
  • the water-soluble resin binder stabilizes the pores formed in the bulk during foaming during the foaming and subsequent drying.
  • the water-soluble resin binder with temperature-dependent viscosity allows a suitable adjustment of the viscosity of the molding compound in adaptation to the individual production steps.
  • methyl cellulose hydroxypropylmethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, ammonium, ethyl celluslose and polyvinyl alcohol.
  • volatilizable hydrocarbons having 5 to 8 carbon atoms in the hydrocarbon radical are cited as means for forming gas bubbles or pores in the molding compound, specifically pentanes, hexanes, octanes, benzene and toluenes.
  • the foamable suspension may additionally contain organic plasticizers. A variety of oils, esters, glycerines and other organics are listed explicitly. The possible addition of specific means for stabilizing the foam state and the shaped microcells is provided.
  • the EP 0 460 392 A1 describes a method of producing foamable metal bodies by the steps of manufacturing, mixing metal powder and gas releasing propellant powder into a molding composition, heat compacting the molding composition under conditions permitting bonding and mechanical strengthening of the metal powders by diffusion, thereby gas tightly enclosing the propellant and simultaneously decomposing the propellant prevent. Furthermore, the compacted molding compound is brought to such a high temperature in an open container or in a mold that the matrix metal melts and the blowing agent decomposes to foam the melt. Depending on the heating and cooling rate, as well as the foaming time at maximum temperature, foam bodies of different pore size and structure are achieved. Titanium hydride, aluminum hydroxide and sodium bicarbonate are mentioned as blowing agents.
  • the object of the present invention is thus to provide an improved process for producing a highly porous metallic U / o ceramic sintered body by means of foaming a molding composition with the aid of a blowing agent.
  • the method thus serves to produce highly porous sintered shaped bodies with a cellular pore structure, ie the shaped body has comparatively thin cell walls, measured on the volume of the pores formed by them.
  • the finished sintered bodies have a solid sintered skeleton of the matrix materials metal u / o ceramic, free of additives, or only with insignificantly small residual amounts of such, the molding compound originally added additives. They have high mechanical strength.
  • the sintered cell walls are largely free of microporosity, but can also be manufactured on request in microporous execution.
  • the cell-like pores have a largely homogeneously uniform mean pore diameter of preferably 0.1 to 10 mm in the finished sintered body, in contrast to a microporosity that is regularly smaller by at least one order of magnitude, as known from sintering technology ,
  • the pore volume in the sintered body is preferably 60-85 vol.%.
  • Such high pore volume fractions are achievable only with strictly geometrically similar, for example honeycomb-like arrangement of the pores in the sintered shaped body.
  • EPS expandable poly-styrene
  • polystyrene blowing agent ie non-foamed polystyrene beads having a particle diameter of preferably 0.1 to 5 mm and containing as the blowing agent the volatile hydrocarbons pentane or hexane in a proportion of 1 to 8 % By weight.
  • copolymers of the monomeric styrene with fractions of acrylic esters or acrylonitrile instead of the pure EPS polystyrene beads.
  • the suitable combination of inventive blowing agent and matched thermoplastic binder components allows foaming of the molding composition up to comparatively very high pore volumes, measured on the known prior art.
  • sintered shaped bodies with greater than 30% by volume up to more than 85% by volume of cell-forming pores are produced in the sintered shaped body.
  • the plasticity of the molding material which is sufficient for foaming, is still present at significantly more than 50% by volume of metallic u / o ceramic matrix powder and correspondingly lower binder content in the prepared, unfoamed molding composition.
  • High proportions of matrix powder favor the subsequent sintering to mechanically strong sintered molded body substantially or make this possible.
  • Known methods aimed at achieving high pore volumes did not allow comparably favorable volume fractions in practice.
  • both the binder components and the inflated polystyrene beads are predominantly discharged from the molding composition via a solution process in organic solvents, such as acetone or ethyl acetate.
  • organic solvents such as acetone or ethyl acetate.
  • the process according to the invention uses, as a preponderantly predominant binder component, already known high-polymer plastics, such as, for example, polyamides, which are insoluble in the abovementioned solvents customary for extraction.
  • binder components used are plasticizers, surfactants and release agents that are as soluble in acetone and ethyl acetate at temperatures above 30 ° C as the polystyrene. These solvent-soluble additional components can lead to microporosity of the (still unsintered) cell walls and facilitate the application of solvent and solutes therein.
  • the proportion of binder in the molding compound must be matched to the materials used in the molding compound and the process parameters for their processing. If this proportion is too high, it impairs the sintering together of the matrix powder during the subsequent sintering process. If the proportion is too low, the foamed molding composition falls below a minimum mechanical strength, which is indispensable for manipulability and further processing.
  • the prepared molding material in a suitable shaping device is to be brought to a temperature suitable for volatilizing the blowing agents in the blowing agent, at the same time as the melting point of the molding compound.
  • Foaming is all the more controlled and uniform the more evenly the polystyrene particles or EPS beads are distributed in the molding compound and the more homogeneous the temperature distribution in the molding compound.
  • the process steps forming the molding compound and foaming can be carried out according to a number of different, previously practiced process.
  • the shaping and foaming of the molding composition has proven particularly useful by known injection molding.
  • Simply dimensioned shaped bodies such as plates, rounds or spheres, can be obtained by pressing a pulverulent EPS-containing molding compound Producing compacts and subsequent foaming with steam in a form perforated by slots economically.
  • the compacts can optionally be laminated with a non-foamable surface layer in a subsequent powder pressing process. This will give you plates or discs with pore-free outer layer.
  • the EPS is incorporated homogeneously into the molding compound melt at temperatures below 80 ° C. on a granulating extruder and the mass strands emerging from the perforated plate of the extruder are knocked off by means of so-called underwater granulation.
  • underwater granulation In order not to have to accept premature gas losses from the EPS beads, it is expedient to carry out the underwater granulation under increased media pressure.
  • Such EPS-containing molding compositions can be easily processed with the usual in plastics processing units to foamed molding compositions on.
  • EPS-containing granules are introduced directly into a vapor-permeable mold and foamed at the same time, as happens to a large extent with prefoamed EPS balls in the packaging industry.
  • this preferred method the production of large-scale and large-volume moldings is feasible.
  • the molding material is brought in a screw or piston press on melting and foaming simultaneously and pressed under high pressure of, for example 10 6 to 10 8 Pascal by a shaping tool.
  • the melt emerging from the mold increases its volume under foaming and is brought to a so-called calibration with simultaneous cooling in its enlarged shape to solidification and thus deducted steadily.
  • the molding composition is cooled to prevent foaming after exiting the extrusion die under high pressure.
  • the shaped mass is reheated, foamed in a volume increase adapted shape, cooled and treated according to the features of the invention.
  • This process variant is used primarily for the production of highly porous, large-area sintered moldings with either open or closed cell structure.
  • metallic and ceramic matrix materials is only in so far as a limitation, as they must be in the form of sinterable powder, a requirement whose implementation belongs to the knowledge of Pulvermetallurgen.
  • Preferred ceramic matrix materials are the oxides of aluminum, silicon and zirconium, as well as silicon nitride and mixtures thereof.
  • metallic matrix materials metals and alloys from the group Fe, Co, Ni, Cu, Ti, Ta, Mo, W and the precious metals, as well as metallic oxides, hydrides and hard metals have proven particularly useful.
  • Sintered bodies produced by the process according to the invention have a wide field of application. The focus is on the application in the field of lightweight components and parts with relatively low thermal conductivity, as well as in the case of open-pored sintered moldings in the field of mechanical filters and catalysts.
  • Example 1 describes the preparation of a porous chromium nickel steel sintered body.
  • Water-atomized chromium nickel powder grade 316 L (Pamco, Japan, 90% particle size less than 15 microns) is in a kneading aggregate with binder components, composed of polyamide, plasticizer, wetting and release agent (the binder), in a weight ratio, 93 , 5% by weight of 316 L powder, 6.5% by weight of binder are thoroughly mixed and kneaded at about 100 ° C. until a low-viscosity melt is present.
  • This mass is discharged from the kneading unit, solidified by cooling and ground to powder of a particle size smaller than 0.3 mm.
  • 140 g of this powder are mixed with 13 g of EPS beads (Styrofoam P 656 from BASF, particle size 0.3 to 0.4 mm) in a laboratory mixer and at room temperature under a pressure of 200 bar to a powder compact of dimensions 60 x 90 x 7.2 mm 3 pressed.
  • This compact is placed in a 20 mm high Al frame of dimensions 70 x 100 mm 2 , its top and bottom surfaces are covered with filter paper and fine mesh and then each with 6 mm thick Al plates, so that a closed, pressure-resistant and yet vapor permeable form arises.
  • the vapor permeability is ensured by holes in the plates of 4 mm diameter and 3 mm spacing.
  • the mold filled with compact is exposed for 4 minutes in a steam autoclave with steam at 120 ° C. under steam pressure of less than 0.7 bar. After cooling the autoclave to less than 100 ° C, the mold is removed and cooled to about 30 ° C under cold water.
  • the molded article of dimensions 70 ⁇ 100 ⁇ 20 mm 3 inflated compact is removed after removal from the mold from the filter paper and dried for 2 h at 60 ° C. He loses 2.5 wt.% Of moisture. Thereafter, the molding is treated for 24 hours, resting on a perforated plate, in 50 ° C warm ethyl acetate as a solvent.
  • the solvent-soluble and dissolved in it substances, already porous shaped body is removed from the bath and freed from the solution by means of vacuum distillation.
  • the not yet extracted portion of polystyrene and binder components, above all polyamide in volatile form is removed from the molding by means of pyrolysis at 500 ° C.
  • a sintered compact of dimensions 61.5 x 88 x 17.3 mm 3 and 130 g of weight is produced. This corresponds to a density of about 1.4 g / cm 3 or a pore volume of 82%.
  • the average diameter of the largely uniformly sized pores, or cells in the sintered shaped body is about 0.60 mm.
  • Example 2 describes the preparation of a porous Al 2 O 3 sintered body.
  • a sinterable Al 2 O 3 powder of 3 microns average particle size and 99.80% purity (grade CT 3000 SG, Fa. ALCOA) in a kneading unit with binder components (polyamide, plasticizer, wetting and release agent) at 100 ° C. mixed thoroughly and kneaded until a low-viscosity melt is present.
  • the weight fractions are 86.0% by weight of CT 3000 SG and 14.0% by weight of binder components.
  • the kneaded mass is discharged from the kneading unit, cooled and ground into powder of a particle size smaller than 0.3 mm.
  • the compact is processed to a foamed compact of dimensions 70 x 100 x 20 mm 3 and then stored for the extraction of soluble substances in ethyl acetate as a solvent.
  • the molded article present after vacuum distillation is 62 g and has the unaltered dimensions of 70 ⁇ 100 ⁇ 20 mm 3.
  • the weight loss compared to the weighing-in amounts at this point to 28 g, which corresponds to 89% of the theoretically extractable amount of substance of 31.5 g equivalent.
  • the sintered compact After pyrolysis of the remaining portions of the polystyrene and the binder components at 500 ° C in air and sintering at 1550 ° C for 60 minutes, the sintered compact has the dimensions 60 x 86 x17 mm 3 and a weight of 56 g. This corresponds to a density of about 0.64 g / cm 3 , or a pore volume of 84%. The mean diameter of the macropores is 0.60 mm.
  • the sintered body is mechanically stable or insensitive to breakage so that it can be manipulated and used without restrictive precautions with only a slight risk of damage.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Powder Metallurgy (AREA)

Abstract

The invention relates to a method for producing highly porous sintered parts, according to which free-flowing thermoplastic moulding materials are expanded at a temperature ranging between 80 and 130 °C. Said method is essentially characterised by the use of expandable polystyrene as the expanding agent, in addition to corresponding binding agents. During the expansion process, encapsulated cellular polystyrene foam particles are formed, allowing the production of mechanically solid sintered bodies with a percentage volume of pores of 85 % and a uniform pore diameter. The method is used to produce open- or closed-pore ceramic and/or metallic sintered bodies.

Description

Die Erfindung betrifft ein Verfahren zur Herstellung eines zellular porösen Sinterformkörpers mit den Fertigungsschritten Aufbereiten einer thermoplastisch fließfähigen Formmasse durch Mischen von Keramik- u/o Metallpulver mit Binderkomponenten und Einarbeitung von organischen Treibmitteln, Überführen der Formmasse in einen schmelzflüssigen Zustand und Einbringen in eine Formgebungsvorrichtung, Aufschäumen der Formmasse mittels des Treibmittels, Verfestigen der geschäumten Formmasse, Ausbringen von Treibmitteln und organischen Komponenten und Sintern des derart behandelten Formkörpers.The invention relates to a method for producing a cellular porous shaped sintered body with the manufacturing steps of preparing a thermoplastic flowable molding compound by mixing ceramic u / o metal powder with binder components and incorporation of organic blowing agents, converting the molding material into a molten state and introduction into a molding device, foaming the molding material by means of the blowing agent, solidification of the foamed molding composition, spreading of blowing agents and organic components and sintering of the thus treated molding.

Es ist bekannt, metallische u/o keramische Formkörper durch Pressen und Sintern geeigneter Ausgangspulver zu fertigen. Fallweise ist dem Matrixpulver ein duktiler Binder beizugeben, beispielsweise ein duktiles Metallpulver bei der Hartmetallherstellung, um press- und sinterfähige Produkte zu erhalten.
Eine vergleichsweise junge Technologie zur Herstellung von keramischen u/o metallischen Sinterformkörpern ist das MIM (metal injection molding) Verfahren, bei dem die keramischen u/o metallischen Matrix - Pulverteilchen mit organischen Binderkomponenten vermischt, die Mischung üblicherweise im thermoplastischen Zustand in die gewünschte Form gebracht, der Formteil verfestigt und danach mittels Pyrolyse u/o durch Lösen und Extrahieren von seinen organischen u/o anorganischen Binderanteilen befreit und schließlich zum annähernd porenfrei dichten Formkörper gesintert wird. Die Formgebung erfolgt alternativ zum Spritzgießen beispielsweise mittels Extrudieren.It is known to produce metallic and / or ceramic shaped bodies by pressing and sintering suitable starting powders. In some cases, a ductile binder has to be added to the matrix powder, for example a ductile metal powder in hard metal production, in order to obtain products which can be pressed and sintered.
A relatively recent technology for producing ceramic metallic sintered shaped bodies is the MIM (metal injection molding) process, in which the ceramic metallic matrix powder particles are mixed with organic binder components, and the mixture is usually brought into the desired shape in the thermoplastic state which solidifies molded part and then freed by pyrolysis u / o by dissolving and extracting its organic and / or inorganic binder components and finally sintered to form an approximately pore-free dense molded body. The shaping takes place alternatively for injection molding, for example by means of extrusion.

Während es üblicherweise das Ziel ist, Sinterformkörper in einen möglichst porenfreien Endzustand zu bringen, so sind auch Anwendungen von Sinterkörpern bekannt, bei denen eine bestimmte Porenstruktur benötigt wird. Gezielte Porenstrukturen in Sinterkörpern werden beispielsweise durch Vermischen der Matrix-Ausgangspulver mit einem pulverförmigen Platzhalter geschaffen, wobei die Platzhalter-Teilchen üblicherweise vor oder während des Sinterprozesses aus dem in Form gebrachten Werkstoffverbund chemisch herausgelöst u/o mittels thermischer Zersetzung entfernt werden und an ihre Stelle Freiräume, bzw. Poren treten. Es ist auch bekannt Porenstrukturen in Formkörpern mittels Einblasen von Gasen, z.B. Argon oder Stickstoffgas, in eine Metallschmelze zu erzeugen. Alternativ werden Sinterkörper mit Porenstruktur hergestellt, indem Treibmittel als Zusatzstoffe möglichst homogen in einen mit Thermoplast - Binder versetzten Matrixwerkstoff eingebracht und dieser Verbund, bzw. diese Formmasse auf Verdampfungs- bzw. Aufschäumtemperatur des Treibmittels erwärmt wird. Dabei bilden sich blasenförmige Gasräume in der, bzw. Schaumgebilde aus der thermoplastischen bzw. schmelzflüssigen Formmasse, die sich bei der Abkühlung und Überführung der Formmasse in einen festen Zustand stabilisieren und danach ein Extrahieren der Gaseinschlüsse bzw. des restlichen Treibmittels unter Zurücklassung von Poren erlauben. Parallel dazu werden die Binderzusätze extrahiert. Die gebrauchsfertige mechanische Stabilisierung des Formkörpers erfolgt mittels eines zusätzlichen Sinterschrittes. Die erzielbare Qualität derart gefertigter, poröser Sinterformkörper, bedeutsam sind deren mechanische Stabilität, mechanische Bearbeitbarkeit, Homogenität der Porenstruktur, Prozentsatz des erreichbaren Porenvolumens, hängt stark von der jeweils eingeschlagenen Prozessführung, von den Hilfsstoffen, Treibmittel und Bindermittel, sowie von der Aufbereitung aller in eine Formmasse eingebrachten Stoffe ab.While it is usually the goal to bring sintered moldings in a possible non-porous final state, so are applications of sintered bodies are known in which a certain pore structure is needed. Targeted pore structures in sintered bodies are created, for example, by mixing the matrix starting powders with a pulverulent placeholder, wherein the placeholder particles usually chemically before or during the sintering process from the molded composite material removed u / o removed by thermal decomposition and take their place free spaces, or pores. It is also known to produce pore structures in moldings by blowing in gases, for example argon or nitrogen gas, into a molten metal. Alternatively, sintered bodies having a pore structure are produced by introducing blowing agents as additives as homogeneously as possible into a matrix material mixed with thermoplastic binder and heating this composite or molding compound to the evaporation or foaming temperature of the blowing agent. In this case, bubble-shaped gas spaces are formed in the, or foam formations of the thermoplastic or molten molding material, which stabilize upon cooling and transfer of the molding compound into a solid state and then allow extraction of the gas inclusions or the remaining propellant leaving pores. In parallel, the binder additives are extracted. The ready mechanical stabilization of the shaped body takes place by means of an additional sintering step. The achievable quality of porous sintered shaped bodies produced in this way, their mechanical stability, mechanical workability, homogeneity of the pore structure, percentage of the achievable pore volume, depend greatly on the process control chosen, on the auxiliaries, blowing agent and binder, as well as on the preparation of all in one Form mass introduced substances.

Die heute verfügbare große Auswahl an organischen und anorganischen Bindern für diese Zwecke ist stark von den Fortschritten in der MIM-Technologie geprägt.
Gleichermaßen ist eine Vielzahl von unterschiedlichen, blähfähigen Stoffen als Treibmittel zur Schaffung von Porenstrukturen in aus Pulvern gefertigten Formkörpern vorbeschrieben.
Allerdings haben einzelne spezifische Kombinationen von Matrixpulver, Bindermittel und Treibmittel in Verbindung mit der jeweiligen Prozessführung einen vielfach nicht vorhersehbaren, wechselseitigen Einfluss auf das Ergebnis bzw. auf die Qualität derartiger poröser Formkörper.The wide range of organic and inorganic binders available today for these purposes is strongly influenced by the advances in MIM technology.
Likewise, a variety of different intumescent materials are described as propellants for creating pore structures in moldings made from powders.
However, individual specific combinations of matrix powder, binder and blowing agent in connection with the respective process control have a frequently unpredictable, mutual influence on the result or on the quality of such porous shaped bodies.

So beschreibt das Patent US 5 213 612 ein Verfahren zur Herstellung eines porösen Metallkörpers, gemäß dessen Ausführungsbeispielen eine wässrige Suspension aus Metallpulver und schäumfähigem Treibmittel innerhalb vorgegebener Volumenverhältnisse gemischt, geschäumt und durch Trocknen zum festen Formkörper gebracht werden. Beim anschließenden Erhitzen des Formkörpers (Schaummittel mit darin verteiltem Metallpulver) auf eine erste Temperaturstufe von 600 - 1200°C kommt es in einer reduzierenden Atmosphäre zu einer Schaummittelzersetzung bei gleichzeitiger teilchenübergreifender Diffusion und metallischen Bindung der Pulverteilchen. Abschließend wird die Temperatur auf eine, dem jeweiligen Metall angepasste Sintertemperatur hochgefahren und das Metallpulver unter Bildung eines porösen Körpers gesintert. Als brauchbares Schaummittel ist ein mit Isocyanat überdecktes Polyoxyäthylen Polyol angeführt, was die Verwendung eines zusätzlichen Bindermittels überflüssig macht. Gemäß einem Ausführungsbeispiel wird unter 50 % Volumensausweitung geschäumt.
Ein Nachteil dieses Verfahrens ist die Verwendung von Wasser in Verbindung mit Polyurethan oder Polyäthylen Bindern, was der so gebildeten Masse wenig thermoplastische Eigenschaften und damit ein Aufschäumen in nur sehr begrenztem Volumenumfang erlaubt. Er kommt zu Schrumpfungen nach dem Aufschäumen. Der praktisch beherrschbare Porenanteil im gesinterten Körper liegt bei 10 - 20 Vol.%, was die Ausbildung von zellularen Porenstrukturen generell ausschließt.This is how the patent describes US 5 213 612 a method for producing a porous metal body, according to which an aqueous suspension of metal powder and foaming blowing agent are mixed within predetermined volume ratios, foamed and brought to the solid molding by drying. During the subsequent heating of the shaped body (foaming agent with metal powder distributed therein) to a first temperature level of 600-1200 ° C., foaming agent decomposition takes place in a reducing atmosphere with simultaneous particle-spreading and metallic binding of the powder particles. Finally, the temperature is raised to a sintering temperature adapted to the respective metal, and the metal powder is sintered to form a porous body. A useful foaming agent is an isocyanate-capped polyoxyethylene polyol, which eliminates the need for an additional binder. According to one embodiment, under 50% volume expansion is foamed.
A disadvantage of this method is the use of water in conjunction with polyurethane or polyethylene binders, which allows the mass thus formed little thermoplastic properties and thus foaming in only a very limited volume. He comes to shrinkage after foaming. The practically controllable pore content in the sintered body is 10-20% by volume, which generally precludes the formation of cellular pore structures.

Die DE 177 15 20 A1 beschreibt ein Verfahren zur Herstellung keramischer Massen durch Gießen, mit Wabenstruktur im Masseninneren und mit glatter Oberfläche, bei dem Kunststoffe mit Perlenstruktur in den temperierten Gießschlicker eingerührt werden und der gegossene Formkörper sich unter Abkühlung verfestigt. Bevorzugter Kunststoff ist treibmittelhaltiges Polystyrol, das je nach gewünschter Perlengröße vorgeschäumt wurde.
Nachteilig bei diesem Verfahren ist eine nur unbefriedigende Steuerbarkeit der Perlenverteilung und -anordnung im Gießschlicker, was die Verwendung des Verfahrens bei auch nur mäßigen Anforderungen an die mechanische Mindesttragfähigkeit der erkalteten Keramikmasse auf die Fertigung von Formkörpern mit nur niedrigem Porenvolumen beschränkt. Das Verfahren sieht keine Ausbringen der Polystyrol-Perlen aus der Masse vor.The DE 177 15 20 A1 describes a method for producing ceramic masses by casting, with honeycomb structure in the mass inside and with a smooth surface, are stirred in the plastics with pearl structure in the tempered casting slurry and the molded body solidifies under cooling. Preferred plastic is blowing agent-containing polystyrene which has been prefoamed depending on the desired bead size.
A disadvantage of this method is only unsatisfactory controllability of the bead distribution and arrangement in the casting slip, which is the use of the method with only moderate requirements for the mechanical minimum capacity of the cooled ceramic mass on the production of Shaped bodies with only low pore volume. The method does not provide for dispensing the polystyrene beads from the mass.

Ein anderes Verfahren der eingangs genannten Art ist in der EP 0 765 704 beschrieben. Die wesentlichen Merkmale des Verfahrens liegen in der getrennten Aufbereitung zweier verschiedener Stoffkomponenten für eine Formmasse, zum einen als eine das Schäum- bzw. Treibmittel in einer harzigen Binder enthaltenden, wässrigen Lösung und zum anderen, als ein Metallpulver und einen wasserlöslichen, harzigen Binder enthaltene Lösung, die beide unmittelbar vor dem geplanten Schäumungsprozess zusammengebracht werden. Der Schäumungsschritt erfolgt in einer Atmosphäre mit mindestens 65 % Luftfeuchtigkeit. Der wasserlösliche Harzbinder stabilisiert die beim Schäumen in der Masse entstandenen Poren während des Schäumens und beim anschließenden Trocknen. Der wasserlösliche Harzbinder mit temperaturabhängiger Viskosität erlaubt eine geeignete Einstellung der Viskosität der Formmasse in Anpassung an die einzelnen Fertigungsschritte. Als Stoffbeispiele für einen derartigen wasserlöslichen Harzbinder werden explizit genannt, Methylzellulose, Hydroxypropylmethylzellulose, Hydroxyäthylzellulose, Karboxymethylzellulose, Ammonium, Äthylzelluslose und Polyvinylalkohol. Weiters werden verflüchtigbare Kohlenwasserstoffe mit 5 bis 8 Kohlenstoffatomen im Kohlenwasserstoff-Radikal als Mittel zur Bildung von Gasblasen bzw. Poren in der Formmasse genannt, und zwar explizit Pentane, Hexane, Oktane, Benzene und Toloene. Die schäumbare Suspension kann zusätzlich organische Plastifizierungsmittel enthalten. Eine Vielzahl von Ölen, Estern, Glyzerinen und anderen organischen Stoffen sind explizit aufgeführt. Die mögliche Zugabe spezifischer Mittel zur Stabilisierung des Schaumzustandes und der geformten Mikrozellen ist vorgesehen. Anders als bei der bisherigen Verwendung handelsüblichen Polyurethans als Schaum- bzw. Treibmittel, soll sich nach diesem Verfahren ein rissfreier und damit mechanisch stabiler, poröser Sinterkörper fertigen lassen. Die in den Beispielen näher ausgeführten Verfahrensschritte lassen die Anfälligkeit des Verfahrens erkennen. Tatsächlich lassen sich nach diesem Verfahren keine für die Mehrzahl der Anwendungsfälle ausreichend mechanisch stabilen, porösen Sinterkörper mit hohem Porenvolumenanteil erzielen. Der dort verwendete Begriff Sinterkörper mit Wabenstruktur hat auf diesem Hintergrund allenfalls eingeschränkten Aussagewert.Another method of the type mentioned is in the EP 0 765 704 described. The essential features of the process lie in the separate preparation of two different components of a molding composition, on the one hand as an aqueous solution containing the foaming or blowing agent in a resinous binder and on the other hand, as a metal powder and a water-soluble, resinous binder solution , which are both brought together just before the planned foaming process. The foaming step takes place in an atmosphere with at least 65% humidity. The water-soluble resin binder stabilizes the pores formed in the bulk during foaming during the foaming and subsequent drying. The water-soluble resin binder with temperature-dependent viscosity allows a suitable adjustment of the viscosity of the molding compound in adaptation to the individual production steps. As examples of such a water-soluble resin binder, there are explicitly mentioned methyl cellulose, hydroxypropylmethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, ammonium, ethyl celluslose and polyvinyl alcohol. Further, volatilizable hydrocarbons having 5 to 8 carbon atoms in the hydrocarbon radical are cited as means for forming gas bubbles or pores in the molding compound, specifically pentanes, hexanes, octanes, benzene and toluenes. The foamable suspension may additionally contain organic plasticizers. A variety of oils, esters, glycerines and other organics are listed explicitly. The possible addition of specific means for stabilizing the foam state and the shaped microcells is provided. Unlike the previous use of commercial polyurethane foam or blowing agent, a crack-free and therefore mechanically stable, porous sintered body should be finished by this method. The method steps detailed in the examples reveal the susceptibility of the method. In fact, according to this method, it is not possible to achieve sufficiently mechanically stable, porous sintered bodies with a high pore volume fraction for the majority of applications. The one used there The term sintered body with honeycomb structure has on this background at most limited information value.

Die EP 0 460 392 A1 beschreibt ein Verfahren zur Herstellung aufschäumbarer Metallkörper mit den Fertigungsschritten, Mischen von Metallpulver und gasabspaltendem Treibmittelpulver zu einer Formmasse, Heißkompaktieren der Formmasse unter Bedingungen, die ein Verbinden und mechanisches Verfestigen der Metallpulver über Diffusion ermöglichen, dabei das Treibmittel gasdicht einschließen und gleichzeitig ein Zersetzen des Treibmittels verhindern. Des Weiteren wird die kompaktierte Formmasse in einem offenen Behälter oder in einer Form auf eine so hohe Temperatur gebracht, dass das Matrixmetall schmilzt und sich das Treibmittel unter Aufschäumen der Schmelze zersetzt. In Abhängigkeit von der Aufheiz- und Abkühlgeschwindigkeit, sowie der Aufschäumdauer bei Maximaltemperatur, werden Schaumkörper unterschiedlicher Porengröße und -struktur erzielt. Als Treibmittel werden Titanhydrid, Aluminiumhydroxid und Natriumbikarbonat genannt.
Nach diesem Verfahren lassen sich indes Metallschäume hohen und homogenen Porenvolumens nur unbefriedigend fertigen. Die zum Aufschäumen notwendige niedrige Formmassenviskosität bedingt eine Erhitzung auf die üblicherweise hohen Metallschmelztemperaturen, was viele Nachteile hat. Es kommt während des Schäumvorganges zur unerwünschten Vereinigung einzelner Gasblasen mit der Gefahr des Kollabierens der schäumenden Formmasse sowie zur Ausbildung von in ihrer Größenverteilung unzureichend beherrschbarer Poren.
Die Aufgabe vorliegender Erfindung besteht somit in der Bereitstellung eines verbesserten Verfahrens zur Herstellung eines hochporösen metallischen u/o keramischen Sinterformkörpers mittels Aufschäumen einer Formmasse unter Zuhilfenahme eines Treibmittels. Die Nachteile bekannter Verfahren, wie zeit-und kostenmäßig aufwändige Prozessschritte, hohe Schäumtemperaturen, Schrumpfung des Formkörpers nach dem Aufschäumen und unzureichende Beeinflussbarkeit der gewünschten Porenstruktur, selbst bei nur mäßig hohem Gesamt-Porenvolumina, sollen vermieden bzw. auf ein deutlich niedrigeres Maß gebracht werden.The EP 0 460 392 A1 describes a method of producing foamable metal bodies by the steps of manufacturing, mixing metal powder and gas releasing propellant powder into a molding composition, heat compacting the molding composition under conditions permitting bonding and mechanical strengthening of the metal powders by diffusion, thereby gas tightly enclosing the propellant and simultaneously decomposing the propellant prevent. Furthermore, the compacted molding compound is brought to such a high temperature in an open container or in a mold that the matrix metal melts and the blowing agent decomposes to foam the melt. Depending on the heating and cooling rate, as well as the foaming time at maximum temperature, foam bodies of different pore size and structure are achieved. Titanium hydride, aluminum hydroxide and sodium bicarbonate are mentioned as blowing agents.
By this method, however, metal foams of high and homogeneous pore volume can only be produced unsatisfactorily. The low molding compound viscosity required for foaming causes heating to the usually high metal melting temperatures, which has many disadvantages. It comes during the foaming process for the unwanted combination of individual gas bubbles with the risk of collapse of the foaming molding composition and the formation of in their size distribution insufficient controllable pores.
The object of the present invention is thus to provide an improved process for producing a highly porous metallic U / o ceramic sintered body by means of foaming a molding composition with the aid of a blowing agent. The disadvantages of known processes, such as time-consuming and expensive process steps, high foaming temperatures, shrinkage of the molding after foaming and insufficient influenceability of the desired pore structure, even with only moderately high total pore volumes, should be avoided or brought to a significantly lower level.

Diese Aufgabe wird für das eingangs beschriebene Verfahren in erfinderischer Weise durch die in den Patentansprüchen genannten Verfahrensmerkmale gelöst.This object is achieved for the method described above in an inventive manner by the method features mentioned in the claims.

Das Verfahren dient somit zur Herstellung hochporöser Sinterformkörper mit zellularer Porenstruktur, d.h. der Formkörper weist vergleichsweise dünne Zellwände auf, gemessen am Volumen der durch sie gebildeten Poren. Die fertigen Sinterformkörper besitzen ein tragfähiges Sinterskelett aus den Matrixwerkstoffen Metall u/o Keramik, frei von Zusätzen, oder nur noch mit unbedeutend kleinen Restanteilen an solchen, der Formmasse ursprünglich beigegebenen Zusätzen. Sie besitzen hohe mechanische Festigkeit. Die gesinterten Zellwände sind weitgehend frei von Mikroporosität, lassen sich auf Wunsch aber auch in mikroporöser Ausführung fertigen.
Die zellenartigen Poren weisen, je nach Anforderungen, einen weitgehend homogen einheitlichen mittleren Porendurchmesser zwischen vorzugsweise 0,1 und 10 mm im fertig gesinterten Körper auf, dies im Unterschied zu einer regelmäßig mindestens um eine Zehnerpotenz kleineren Mikroporosität, wie sie von der Sintertechnologie her bekannt ist. Das Porenvolumen im Sinterkörper beträgt vorzugsweise
60 - 85 Vol.%. Solche hohen Porenvolumenanteile sind nur bei streng geometrisch gleichartiger, beispielsweise wabenartiger Anordnung der Poren im Sinterformkörper erreichbar.The method thus serves to produce highly porous sintered shaped bodies with a cellular pore structure, ie the shaped body has comparatively thin cell walls, measured on the volume of the pores formed by them. The finished sintered bodies have a solid sintered skeleton of the matrix materials metal u / o ceramic, free of additives, or only with insignificantly small residual amounts of such, the molding compound originally added additives. They have high mechanical strength. The sintered cell walls are largely free of microporosity, but can also be manufactured on request in microporous execution.
Depending on the requirements, the cell-like pores have a largely homogeneously uniform mean pore diameter of preferably 0.1 to 10 mm in the finished sintered body, in contrast to a microporosity that is regularly smaller by at least one order of magnitude, as known from sintering technology , The pore volume in the sintered body is preferably
60-85 vol.%. Such high pore volume fractions are achievable only with strictly geometrically similar, for example honeycomb-like arrangement of the pores in the sintered shaped body.

Zur Ausbildung großporig zellularer Strukturen wird als Polystyrol Treibmittel vorzugsweise handelsübliches EPS (expandierfähiges Poly-Styrol) verwendet, d.h. nichtgeschäumte Polystyrolperlen mit Teilchendurchmesser von vorzugsweise 0,1 bis 5 mm, die als Blähmittel die leichtflüchtigen Kohlenwasserstoffe Pentan oder Hexan in einem Anteil von 1 bis 8 Gew.% enthalten.
Für eine gezielte Einflussnahme auf die Schäumcharakteristik können auch Copolymerisate des monomeren Styrol mit Anteilen an Acrylsäureestern oder Acrylnitril anstelle der reinen EPS Polystyrolperlen verwendet werden.For the formation of large-pored cellular structures, commercially available EPS (expandable poly-styrene) is preferably used as the polystyrene blowing agent, ie non-foamed polystyrene beads having a particle diameter of preferably 0.1 to 5 mm and containing as the blowing agent the volatile hydrocarbons pentane or hexane in a proportion of 1 to 8 % By weight.
For a specific influence on the foaming characteristic, it is also possible to use copolymers of the monomeric styrene with fractions of acrylic esters or acrylonitrile instead of the pure EPS polystyrene beads.

Vorwiegend von der MIM―Technologie ist eine Vielzahl von thermoplastischen Binderwerkstoffen und Kombinationen einzelner Binderkomponenten bekannt. Mittels einer dem Fachmann geläufigen Komponentenauswahl erreicht man eine breite Vielfalt von auf die jeweilige Anforderung anpassbaren Bindern. Für die bestimmungsgemäße Durchführung vorliegender Erfindung ist aber gerade die Gewährleistung einer geeignet niedrigen Schmelzviskosität der gesamten Formmasse bei der durch die Gasfreisetzung des Treibmittels vorgegebenen Aufschäumtemperatur von 80 bis 130°C von großer Bedeutung.
Angelehnt an den Sprachgebrauch in der MIM―Technologie spricht man dann von einer erschmolzenen Formmasse für die Mischung aus vorzugsweise organischen Binderkomponenten und Matrixpulver, wenn diese einen niedrigviskosen, breiigen Zustand besitzt. -Mainly of the MIM technology is a variety of thermoplastic binder materials and combinations of individual binder components known. By means of a component selection familiar to the person skilled in the art, a broad variety of binders which can be adapted to the respective requirement can be achieved. For the intended implementation of the present invention, however, it is precisely the guarantee of a suitably low melt viscosity of the entire molding composition at the foaming temperature of 80 to 130 ° C. which is predetermined by the gas release of the blowing agent of great importance.
Based on the language used in MIM technology is then called a molten molding composition for the mixture of preferably organic binder components and matrix powder, if this has a low-viscosity, pulpy state. -

Die geeignete Kombination aus erfindungsgemäßem Treibmittel und darauf abgestimmten thermoplastischen Binderkomponenten erlaubt ein Aufschäumen der Formmasse bis zu vergleichsweise sehr hohen Porenvolumina, gemessen am bekannten Stand der Technik. Nach bevorzugten Ausführung des Verfahrens werden Sinterformkörper mit größer 30 bis zu über 85 Vol.% zellbildenden Poren im gesinterten Formkörper gefertigt.
Die für das Aufschäumen ausreichende Plastizität der Formmasse ist noch bei deutlich über 50 % Volumenanteil an metallischem u/o keramischen Matrixpulver und entsprechend geringerem Binderanteil in der aufbereiteten, ungeschäumten Formmasse gegeben. Hohe Matrixpulver―Anteile begünstigen die nachfolgende Sinterung zum mechanisch festen Sinterformkörper wesentlich oder machen diese erst möglich. Bekannte, auf die Erzielung hoher Porenvolumina ausgerichtete Verfahren, ließen vergleichbar günstige Volumenanteile in der Praxis nicht zu. Bekannte Verfahren verlangen vielmehr große Kompromisse, was die gleichzeitige Sinterstabilität und hohes Porenvolumen im Sinterformkörper anbelangt.
Mechanisch feste Sinterformkörper mit stabilem Sinterskelett und hohem Poren-Volumenanteilen sind gemäß Erfindung über die Verwendung von EPS als Treibmittel erreichbar, weil dieses im Unterschied zu Treibmitteln entsprechend dem bekannten Stand der Technik nicht allein zur Freisetzung von Gasen zwecks Gasblasen- und Porenbildung in der Formmasse, sondern vielmehr zur Ausbildung aufgeschäumter, mechanisch tragender, in sich geschlossener Polystyrol-Schaumstoffkügelchen führt. Nur so lässt sich das bei bisherigen Verfahren gefürchtete Kollabieren aufgeschäumter Schmelzen ab einer bestimmten, vergleichsweise geringen Porengröße vermeiden. Es kommt beim vorliegenden Verfahren weder zur Vereinigung einzelner kleiner zu einer großen Gasblase, bzw. Pore, noch zum Zusammenfallen aufgeschäumter Formmassen mangels ausreichender Thermoplastizität bei Überschreiten der Grenzoberflächenspannung zwischen Gasblase und Formmasse.The suitable combination of inventive blowing agent and matched thermoplastic binder components allows foaming of the molding composition up to comparatively very high pore volumes, measured on the known prior art. According to a preferred embodiment of the method, sintered shaped bodies with greater than 30% by volume up to more than 85% by volume of cell-forming pores are produced in the sintered shaped body.
The plasticity of the molding material, which is sufficient for foaming, is still present at significantly more than 50% by volume of metallic u / o ceramic matrix powder and correspondingly lower binder content in the prepared, unfoamed molding composition. High proportions of matrix powder favor the subsequent sintering to mechanically strong sintered molded body substantially or make this possible. Known methods aimed at achieving high pore volumes did not allow comparably favorable volume fractions in practice. On the contrary, known methods require great compromises with regard to the simultaneous sintering stability and high pore volume in the sintered shaped body.
Mechanically strong sintered moldings with stable sintered skeleton and high pore volume fractions can be achieved according to the invention via the use of EPS as blowing agent, because this, in contrast to blowing agents according to the known state of the art, is not solely responsible for the release of gases for the purpose of gas bubble and pore formation in the molding compound. rather rather leads to the formation of foamed, mechanically bearing, self-contained polystyrene foam beads. This is the only way to avoid the collapse of foamed melts, which was dreaded in previous processes, beyond a certain, comparatively small pore size. It comes in the present method neither to unite individual small to a large gas bubble, or pore, nor to collapse foamed molding compositions for lack of sufficient thermoplasticity when exceeding the surface tension boundary between the gas bubble and molding compound.

Mittels einer, dem Fachmann geläufigen Abstimmung der chemisch/physikalischer Eigenschaften der Binderkomponenten auf das erfindungsgemäße Treibmittel lässt sich als weiterer Vorteil des erfinderischen Verfahrens eine bisher nicht erreichte mechanische Porenstabilisierung in der aufgeschäumten Formmasse erreichen. Üblicherweise werden in einem, dem Aufschäumen folgenden Schritt sowohl die Binderkomponenten, als auch die aufgeblähten Polystyrol - Kügelchen über einen Lösungsprozess in organischen Lösungsmitteln, wie Aceton oder Ethylacetat zum überwiegenden Anteil aus der Formmasse ausgebracht. Dabei geht die mechanische Formstabilität verloren. Das erfindungsgemäße Verfahren verwendet als anteilsmäßig überwiegende Binderkomponente als solchen bereits bekannte hochpolymere Kunststoffe, wie z.B. Polyamide, die in den für das Extrahieren üblichen, oben genannten Lösungsmitteln unlöslich ist.
Weitere verwendete Binderkomponenten sind Weichmacher, Tenside und Trennmittel, die in Aceton und Ethylacetat bei Temperaturen über 30°C ebenso gut löslich sind wie das Polystyrol. Diese, im Lösungsmittel löslichen Zusatzkomponenten können zu einer Mikroporosität der (noch ungesinterten) Zellwände führen und die Ausbringung von Lösungsmittel und darin gelösten Stoffen erleichtern. Es ist nun der beim Extraktionsprozess nicht aus der geschäumten Formmasse herauslösbare hochpolymere Kunststoff, der den metallischen u/o keramischen Pulverteilchen noch bei einem Makroporenanteil von 85 Vol.% in der Formmasse ausreichende mechanische Festigkeit verleiht, und zwar einerseits für den ohne Volumenschrumpfung erfolgenden Extraktionsschritt, als auch weiterhin für eine Manipulation des extrahierten, ungesinterten Formkörpers, und schließlich für die, bezüglich Formerhaltung kritischen Anfangsphase des Sintervorgangs der metallischen u/o keramischen Pulverteilchen bis zum Zeitpunkt der rückstandsfreien Pyrolyse des Binders bei 500°C.By means of coordination of the chemical / physical properties of the binder components with the blowing agent according to the invention, which is familiar to the person skilled in the art, a further advantage of the inventive method is achieved in the foamed molding composition which has hitherto not been achieved. Usually, in a step following the foaming, both the binder components and the inflated polystyrene beads are predominantly discharged from the molding composition via a solution process in organic solvents, such as acetone or ethyl acetate. The mechanical dimensional stability is lost. The process according to the invention uses, as a preponderantly predominant binder component, already known high-polymer plastics, such as, for example, polyamides, which are insoluble in the abovementioned solvents customary for extraction.
Other binder components used are plasticizers, surfactants and release agents that are as soluble in acetone and ethyl acetate at temperatures above 30 ° C as the polystyrene. These solvent-soluble additional components can lead to microporosity of the (still unsintered) cell walls and facilitate the application of solvent and solutes therein. It is now the high-polymer plastic which can not be dissolved out of the foamed molding material during the extraction process which gives the metallic metallic powder particles sufficient mechanical strength even with a macroporous fraction of 85% by volume in the molding compound, on the one hand for the extraction step without volume shrinkage, as well as for manipulation of the extracted, unsintered shaped body, and finally for, with respect to shape preservation critical initial phase of the sintering process of the metallic u / o ceramic powder particles until the time of residue-free pyrolysis of the binder at 500 ° C.

Der Anteil des Binders in der Formmasse muss auf die eingesetzten Werkstoffe in der Formmasse und auf die Prozessparameter für deren Verarbeitung abgestimmt werden. Ist dieser Anteil zu hoch, so beeinträchtigt er das Zusammensintern der Matrixpulver beim anschließenden Sinterprozess. Ist der Anteil zu gering, so unterschreitet die geschäumte Formmasse eine mechanische Mindestfestigkeit, die für eine Manipulier- und Weiterverarbeitbarkeit unerlässlich ist.The proportion of binder in the molding compound must be matched to the materials used in the molding compound and the process parameters for their processing. If this proportion is too high, it impairs the sintering together of the matrix powder during the subsequent sintering process. If the proportion is too low, the foamed molding composition falls below a minimum mechanical strength, which is indispensable for manipulability and further processing.

Für den Aufschäumprozess ist die aufbereitete Formmasse in einer geeigneten Formgebungsvorrichtung auf eine für die Verflüchtigung der Blähstoffe im Treibmittel geeignete Temperatur, zugleich Schmelztemperatur der Formmasse, zu bringen. Das Aufschäumen gelingt um so kontrollierter und gleichmäßiger, je gleichmäßiger die Polystyrol-Teilchen, bzw. EPS-Perlen in der Formmasse verteilt sind und je homogener die Temperaturverteilung in der Formmasse ist.
Bei Verwendung einer mit feinen Schlitzen versehenen Form als Formgebungsvorrichtung in einem druckkontrollierten Autoklaven lassen sich besonders gute Ergebnisse hinsichtlich Zellhomogenität, Zellstruktur und Volumenanteil der Poren in der Formmasse erzielen.For the foaming process, the prepared molding material in a suitable shaping device is to be brought to a temperature suitable for volatilizing the blowing agents in the blowing agent, at the same time as the melting point of the molding compound. Foaming is all the more controlled and uniform the more evenly the polystyrene particles or EPS beads are distributed in the molding compound and the more homogeneous the temperature distribution in the molding compound.
When using a form provided with fine slots as a shaping device in a pressure-controlled autoclave, particularly good results can be achieved with regard to cell homogeneity, cell structure and volume fraction of the pores in the molding compound.

Die Verfahrensschritte Formung der Formmasse und Aufschäumen lassen sich nach einer Reihe verschiedener, schon bisher praktizierter Verfahren durchführen.The process steps forming the molding compound and foaming can be carried out according to a number of different, previously practiced process.

Für die Fertigung geometrisch komplexer Formteile hat sich die Formgebung und Aufschäumung der Formmasse mittels bekannter Spritzgießverfahren besonders bewährt.For the production of geometrically complex moldings, the shaping and foaming of the molding composition has proven particularly useful by known injection molding.

Einfach dimensionierte Formkörper, wie Platten, Ronden oder Kugeln, lassen sich durch Pressen einer pulverförmigen EPS-haltigen Formmasse zu Presslingen und nachträgliches Aufschäumen mit Dampf in einer durch Schlitze perforierten Form wirtschaftlich herstellen. Gemäß einer Verfahrensvariante lassen sich die Presslinge in einem nachfolgenden Pulver-Pressvorgang wahlweise mit einer nicht schäumbaren Oberflächenschicht kaschieren. Damit erlangt man Platten oder Ronden mit porenfreier Außenschicht.Simply dimensioned shaped bodies, such as plates, rounds or spheres, can be obtained by pressing a pulverulent EPS-containing molding compound Producing compacts and subsequent foaming with steam in a form perforated by slots economically. According to a variant of the method, the compacts can optionally be laminated with a non-foamable surface layer in a subsequent powder pressing process. This will give you plates or discs with pore-free outer layer.

Nach einer anderen wirtschaftlichen Schrittfolge gemäß Erfindung wird auf einem Granulierextruder das EPS bei Temperaturen unterhalb von 80°C in die Formmassenschmelze homogen eingearbeitet und es werden die an der Lochplatte des Extruders austretenden Massestränge mittels der sogenannten Unterwassergranulation abgeschlagen. Um keine vorzeitigen Gasverluste aus den EPS-Perlen hinnehmen zu müssen ist es zweckmäßig, die Unterwassergranulation unter erhöhtem Mediendruck vorzunehmen. Derartige EPS-haltige Formmassengranulate lassen sich mit den in der Kunststoffverarbeitung üblichen Aggregaten problemlos zu geschäumten Formmassenkörpem weiter verarbeiten.According to another economic step sequence according to the invention, the EPS is incorporated homogeneously into the molding compound melt at temperatures below 80 ° C. on a granulating extruder and the mass strands emerging from the perforated plate of the extruder are knocked off by means of so-called underwater granulation. In order not to have to accept premature gas losses from the EPS beads, it is expedient to carry out the underwater granulation under increased media pressure. Such EPS-containing molding compositions can be easily processed with the usual in plastics processing units to foamed molding compositions on.

Nach einer ähnlichen Verfahrensvariante werden EPS-haltige Granulate direkt in eine dampfdurchlässige Form eingebracht und zeitgleich aufgeschäumt, wie dies in großem Umfang mit vorgeschäumten EPS-Kugeln in der Verpackungsindustrie geschieht. Mittels dieses bevorzugten Verfahrens ist auch die Fertigung großflächiger und großvolumiger Formteile durchführbar.After a similar process variant, EPS-containing granules are introduced directly into a vapor-permeable mold and foamed at the same time, as happens to a large extent with prefoamed EPS balls in the packaging industry. By means of this preferred method, the production of large-scale and large-volume moldings is feasible.

Bei Einbeziehung des Extrudierens in das erfinderische Verfahren wird die Formmasse in einer Schnecken- oder Kolbenpresse auf Schmelz- und zugleich Aufschäumtemperatur gebracht und unter hohem Druck von beispielsweise 106 bis 108 Pascal durch ein formgebendes Werkzeug gedrückt. Die aus dem Werkzeug austretende Schmelze vergrößert unter Aufschäumen ihr Volumen und wird in einer sogenannten Kalibrierung unter gleichzeitiger Kühlung in ihrer vergrößerten Gestalt zur Erstarrung gebracht und dergestalt stetig abgezogen.When incorporating the extrusion in the inventive method, the molding material is brought in a screw or piston press on melting and foaming simultaneously and pressed under high pressure of, for example 10 6 to 10 8 Pascal by a shaping tool. The melt emerging from the mold increases its volume under foaming and is brought to a so-called calibration with simultaneous cooling in its enlarged shape to solidification and thus deducted steadily.

Entsprechend einer Variante der Extrudier-Schrittfolge wird die Formmasse zur Verhinderung des Aufschäumens nach dem Austritt aus dem Extrudierwerkzeug unter hohem Druck abgekühlt. In einer anschließenden Schrittfolge wird die geformte Masse erneut erwärmt, in einer der Volumenvergrößerung angepassten Form geschäumt, abgekühlt und entsprechend den Erfindungsmerkmalen weiterbehandelt. Diese Verfahrensvariante dient vor allem der Fertigung von hochporösen, großflächigen Sinterformteilen mit wahlweise offener oder geschlossener Zellstruktur.According to a variant of the extrusion step sequence, the molding composition is cooled to prevent foaming after exiting the extrusion die under high pressure. In a subsequent In sequence, the shaped mass is reheated, foamed in a volume increase adapted shape, cooled and treated according to the features of the invention. This process variant is used primarily for the production of highly porous, large-area sintered moldings with either open or closed cell structure.

Das erfindungswesentliche Verfahren ergibt, im Unterschied zu der bevorzugten Herstellung von Sinterformkörpern mit geschlossenen Poren, bzw. Zellen, immer dann offene Zellstrukturen, wenn entweder die Dehnbarkeit der Formmassenschmelze zu klein ist für die Geschwindigkeit und das Ausmaß des Aufschäumens - und diese kann man gezielt steuern, oder wenn der Aufschäumprozess beispielsweise durch Vergrößerung des EPS-Anteils in der Formmasse so beeinflusst wird, dass die zur Ausbildung und Beibehaltung geschlossener Zellen lokal bereitzustellende Formmassenmenge nicht ausreichend ist, so dass die sich weiter aufblähenden EPS-Kügelchen direkten Flächenkontakt zu ihren angrenzenden Nachbarn erhalten.The process essential to the invention, in contrast to the preferred production of sintered compacts with closed pores or cells, always open cell structures, either either the ductility of the molten mass melt is too small for the speed and extent of foaming - and these can be controlled specifically or if the foaming process is influenced, for example, by increasing the proportion of EPS in the molding compound such that the molding composition to be provided locally to form and maintain closed cells is insufficient, so that the further expanding EPS beads receive direct surface contact with their adjacent neighbors ,

Hinsichtlich der Auswahl an für das erfindungsgemäße Verfahren geeigneten metallischen und keramischen Matrixwerkstoffen besteht nur in sofern eine Einschränkung, als diese in Form sinterfähiger Pulver vorliegen müssen, eine Forderung, deren Umsetzung zum Wissen des Pulvermetallurgen gehört. Bevorzugte keramische Matrixwerkstoffe sind die Oxide des Aluminium, Silizium und Zirkonium, sowie Siliziumnitrid und Mischungen derselben.
Als metallische Matrixwerkstoffe haben sich Metalle und Legierungen aus der Gruppe Fe, Co, Ni, Cu, Ti, Ta, Mo, W und die Edelmetalle, sowie metallische Oxide, Hydride und Hartmetalle besonders bewährt.With regard to the selection of suitable for the process according to the invention metallic and ceramic matrix materials is only in so far as a limitation, as they must be in the form of sinterable powder, a requirement whose implementation belongs to the knowledge of Pulvermetallurgen. Preferred ceramic matrix materials are the oxides of aluminum, silicon and zirconium, as well as silicon nitride and mixtures thereof.
As metallic matrix materials, metals and alloys from the group Fe, Co, Ni, Cu, Ti, Ta, Mo, W and the precious metals, as well as metallic oxides, hydrides and hard metals have proven particularly useful.

Sinterformkörper, hergestellt nach dem erfindungsgemäßen Verfahren, besitzen ein weites Anwendungsfeld. Schwerpunktmäßig liegt die Anwendung im Bereich der Leichtbauteile und bei Teilen mit vergleichsweise geringer thermischer Leitfähigkeit, sowie im Fall offenporiger Sinterformteile im Bereich mechanischer Filter und Katalysatoren.Sintered bodies produced by the process according to the invention have a wide field of application. The focus is on the application in the field of lightweight components and parts with relatively low thermal conductivity, as well as in the case of open-pored sintered moldings in the field of mechanical filters and catalysts.

Die Erfindung wird durch nachfolgende Verfahrensbeispiele näher beschrieben.The invention is described in more detail by the following process examples.

Beispiel 1 beschreibt die Herstellung eines porösen Chromnickelstahl―Sinterformkörpers. Wasserverdüstes Chromnickel-Pulver der Sorte 316 L (Fa. Pamco,Japan, Teilchengröße zu 90 % kleiner 15 µm) wird in einem Knetaggregat mit Binderkomponenten, zusammengesetzt aus Polyamid, Weichmacher, Netz-und Trennmittel (der Binder), in einem Gewichtverhältnis, 93,5 Gew.% 316 L Pulver, 6,5 Gew.% Binder bei ca. 100°C intensiv gemischt und geknetet, bis eine niedrigviskose Schmelze vorliegt.
Diese Masse wird aus dem Knetaggregat ausgetragen , durch Abkühlen verfestigt und zu Pulver einer Teilchengröße kleiner 0,3 mm vermahlen. 140 g dieses Pulvers werden mit 13 g EPS―Perlen (Styropor P 656 der Fa. BASF, Teilchengröße 0,3 bis 0,4 mm)in einem Labormischer vermischt und bei Raumtemperatur unter einem Pressdruck von 200 bar zu einem Pulverpressling der Abmessungen 60 x 90 x 7,2 mm3 verpresst.
Dieser Pressling wird in einen 20 mm hohen Al-Rahmen der Abmessung 70 x 100 mm2 eingebracht, seine Ober- und Unterfläche werden mit Filterpapier und feinem Siebgewebe und anschließend mit jeweils 6 mm dicken Al-Platten abgedeckt, sodass eine geschlossene, druckfeste und doch dampfdurchlässig Form entsteht. Die Dampfdurchlässigkeit wird durch Löcher in den Platten von 4 mm Durchmesser und 3 mm Abstand gewährleistet.
Die mit Pressling gefüllte Form wird 4 min lang in einem Dampfautoklaven mit unter 0,7 bar Dampfüberdruck stehenden, 120°C heißen Wasserdampf ausgesetzt. Nach dem Abkühlen des Autoklaven auf weniger als 100°C wird die Form entnommen und unter kaltem Wasser auf etwa 30°C abgekühlt. Der zum Formkörper der Abmessungen 70 x 100 x 20 mm3 aufgeblähte Pressling wird nach der Entnahme aus der Form vom Filterpapier befreit und während 2 h bei 60°C getrocknet. Dabei verliert er 2,5 Gew.% an Feuchtigkeit.
Daraufhin wird der Formkörper während 24 h, auf einer gelochten Unterlagplatte ruhend, in 50°C warmem Ethylacetat als Lösungsmittel behandelt. Anschließend wird der mit Lösungsmittel und darin gelösten Stoffen vollgesogene, bereits poröse Formkörper dem Bad entnommen und mittels Vakuumdestillation von der Lösung befreit. Der verbleibende, noch ungesinterte Formkörper weist bei gegenüber dem geschäumten Formkörper unveränderter Außenabmessung ein Gewicht von 137 g auf. Aus einem Vergleich mit dem eingewogenen Gewicht der Formmasse
(140 g + 13 g = 153 g) ergibt sich ein Gewichtsverlust von 16 g, was, bezogen auf 17,2 g theoretisch extrahierbarer Stoff, einem Anteil von 93,0 % entspricht. Als erste Stufe des abschließenden Formkörper-Sinterns wird mittels Pyrolyse bei 500°C der noch nicht extrahierte Anteil an Polystyrol und Binderkomponenten, vor allem Polyamid in flüchtiger Form aus dem Formkörper entfernt. Mit dem weiteren Sinterprozess während 60 min bei 1320°C wird ein Sinterformkörper der Abmessungen 61,5 x 88 x 17,3 mm3 und von 130 g Gewicht hergestellt.
Das entspricht einer Dichte von ca. 1,4 g/cm3 oder einem Porenvolumen von 82%.
Der mittlere Durchmesser der weitgehend einheitlich großen Poren, bzw. Zellen im Sinterformkörper beträgt ca. 0,60 mm.Example 1 describes the preparation of a porous chromium nickel steel sintered body. Water-atomized chromium nickel powder grade 316 L (Pamco, Japan, 90% particle size less than 15 microns) is in a kneading aggregate with binder components, composed of polyamide, plasticizer, wetting and release agent (the binder), in a weight ratio, 93 , 5% by weight of 316 L powder, 6.5% by weight of binder are thoroughly mixed and kneaded at about 100 ° C. until a low-viscosity melt is present.
This mass is discharged from the kneading unit, solidified by cooling and ground to powder of a particle size smaller than 0.3 mm. 140 g of this powder are mixed with 13 g of EPS beads (Styrofoam P 656 from BASF, particle size 0.3 to 0.4 mm) in a laboratory mixer and at room temperature under a pressure of 200 bar to a powder compact of dimensions 60 x 90 x 7.2 mm 3 pressed.
This compact is placed in a 20 mm high Al frame of dimensions 70 x 100 mm 2 , its top and bottom surfaces are covered with filter paper and fine mesh and then each with 6 mm thick Al plates, so that a closed, pressure-resistant and yet vapor permeable form arises. The vapor permeability is ensured by holes in the plates of 4 mm diameter and 3 mm spacing.
The mold filled with compact is exposed for 4 minutes in a steam autoclave with steam at 120 ° C. under steam pressure of less than 0.7 bar. After cooling the autoclave to less than 100 ° C, the mold is removed and cooled to about 30 ° C under cold water. The molded article of dimensions 70 × 100 × 20 mm 3 inflated compact is removed after removal from the mold from the filter paper and dried for 2 h at 60 ° C. He loses 2.5 wt.% Of moisture.
Thereafter, the molding is treated for 24 hours, resting on a perforated plate, in 50 ° C warm ethyl acetate as a solvent. Subsequently, the solvent-soluble and dissolved in it substances, already porous shaped body is removed from the bath and freed from the solution by means of vacuum distillation. The remaining, still unsintered Shaped body has a weight of 137 g with respect to the foamed molding unchanged outer dimensions. From a comparison with the weight of the molding compound
(140 g + 13 g = 153 g) results in a weight loss of 16 g, which, based on 17.2 g of theoretically extractable material, corresponding to a share of 93.0%. As the first stage of the final molding sintering, the not yet extracted portion of polystyrene and binder components, above all polyamide in volatile form, is removed from the molding by means of pyrolysis at 500 ° C. With the further sintering process for 60 min at 1320 ° C, a sintered compact of dimensions 61.5 x 88 x 17.3 mm 3 and 130 g of weight is produced.
This corresponds to a density of about 1.4 g / cm 3 or a pore volume of 82%.
The average diameter of the largely uniformly sized pores, or cells in the sintered shaped body is about 0.60 mm.

Beispiel 2 beschreibt die Herstellung eines porösen Al2O3-Sinterformkörpers.
Dazu wird ein sinterfähiges Al2O3-Pulver von 3 µm mittlerer Teilchengröße und 99,80 % Reinheit (Sorte CT 3000 SG, Fa. ALCOA) in einem Knetaggregat mit Binderkomponenten (Polyamid, Weichmacher, Netz- und Trennmittel) bei 100°C intensiv gemischt und geknetet, bis eine niedrigviskose Schmelze vorliegt. Die Gewichtsanteile betragen, 86,0 Gew.% CT 3000 SG und 14,0 Gew.% Binderkomponenten.
Entsprechend Beispiel 1 wird die geknetete Masse aus dem Knetaggregat ausgetragen, abgekühlt und zu Pulver einer Teilchengröße kleiner 0,3 mm vermahlen.
Daraufhin wird 65 g dieser Pulvermasse mit 25 g EPS-Perlen (Styropor P 656, Fa. BASF, Teilchengröße 0,3 bis 0,4 mm) in einem Labormischer vermischt und bei Raumtemperatur unter 200 bar Pressdruck zu einem Pressling der Abmessung 60 x 90 x 12 mm3 verpresst.Example 2 describes the preparation of a porous Al 2 O 3 sintered body.
For this purpose, a sinterable Al 2 O 3 powder of 3 microns average particle size and 99.80% purity (grade CT 3000 SG, Fa. ALCOA) in a kneading unit with binder components (polyamide, plasticizer, wetting and release agent) at 100 ° C. mixed thoroughly and kneaded until a low-viscosity melt is present. The weight fractions are 86.0% by weight of CT 3000 SG and 14.0% by weight of binder components.
According to Example 1, the kneaded mass is discharged from the kneading unit, cooled and ground into powder of a particle size smaller than 0.3 mm.
Then 65 g of this powder mass is mixed with 25 g of EPS beads (Styrofoam P 656, BASF, particle size 0.3 to 0.4 mm) in a laboratory mixer and at room temperature under 200 bar pressing pressure to a compact of the dimension 60 x 90 x 12 mm 3 pressed.

Analog Beispiel 1 wird der Pressling zu einem geschäumten Pressling der Abmessungen 70 x 100 x 20 mm3 verarbeitet und anschließend zur Extraktion löslicher Stoffe in Ethylacetat als Lösungsmittel gelagert.
Der nach der Vakuumdestillation vorliegende Formkörper ist 62 g schwer und weist die unveränderten Abmessungen 70 x 100 x 20 mm3 auf Der Gewichtsverlust gegenüber der Einwage beträgt zu diesem Zeitpunkt 28 g, was einem Wert von 89 % der theoretisch extrahierbaren Stoffmenge von 31,5 g entspricht.
Nach der Pyrolyse der restlichen Anteile des Polystyrols und der Binderkomponenten bei 500°C in Luft und einer 60 minütigen Sinterung bei 1550°C weist der Sinterformkörper die Maße 60 x 86 x17 mm3 und ein Gewicht von 56 g auf.
Das entspricht einer Dichte von ca. 0,64 g/ cm3, bzw. einem Porenvolumen von 84 %.
Der mittlere Durchmesser der Makroporen beträgt 0,60 mm.
Der Sinterkörper ist mechanisch so stabil, bzw. bruchunempfindlich, dass er ohne einschränkende Vorsichtsmaßnahmen bei nur geringem Beschädigungsrisiko manipulierbar und nutzbar ist.Analogously to Example 1, the compact is processed to a foamed compact of dimensions 70 x 100 x 20 mm 3 and then stored for the extraction of soluble substances in ethyl acetate as a solvent.
The molded article present after vacuum distillation is 62 g and has the unaltered dimensions of 70 × 100 × 20 mm 3. The weight loss compared to the weighing-in amounts at this point to 28 g, which corresponds to 89% of the theoretically extractable amount of substance of 31.5 g equivalent.
After pyrolysis of the remaining portions of the polystyrene and the binder components at 500 ° C in air and sintering at 1550 ° C for 60 minutes, the sintered compact has the dimensions 60 x 86 x17 mm 3 and a weight of 56 g.
This corresponds to a density of about 0.64 g / cm 3 , or a pore volume of 84%.
The mean diameter of the macropores is 0.60 mm.
The sintered body is mechanically stable or insensitive to breakage so that it can be manipulated and used without restrictive precautions with only a slight risk of damage.

Claims (15)

  1. A process for producing a cellular shaped sintered body, which comprises the manufacturing steps of preparation of a thermoplastically flowable molding composition by mixing of ceramic and/or metal powder with binder components and incorporation of organic and/or inorganic blowing agents, conversion of the molding composition into a molten state and introduction into a shaping device, foaming of the molding composition by means of the blowing agent, solidification of the foamed molding composition, removal of blowing agents and organic components and sintering of the shaped body which has been treated in this way, characterized in that expandable polystyrene particles are used as blowing agent and the foaming step is carried out at temperatures of from 80° to 130°C in a mold which leaves room for expansion of the molding composition to form individual polystyrene foam particles which each take up a closed space in the molding composition and have a narrow diameter distribution.
  2. The process as claimed in claim 1, characterized in that bead-shaped polystyrene particles having a mean diameter of from 0.1 to 5 mm and a small scatter of the diameter are used.
  3. The process as claimed in claim 1 or 2, characterized in that a copolymer of monomeric styrene and acrylic esters or acrylonitrile is used as blowing agent.
  4. The process as claimed in any of claims 1 to 3, characterized in that polystyrene comprising pentane or hexane as expandable agent is used.
  5. The process as claimed in any of claims 1 to 4, characterized in that the blowing agent is incorporated as solid, not preexpanded pellets into the mixture for the molding composition.
  6. The process as claimed in any of claims 1 to 5, characterized in that small proportions of other thermally unstable, gas-releasing substances are additionally mixed into the molding composition physically separately from the expandable polystyrene particles to form micropores in the shaped body.
  7. The process as claimed in any of claims 1 to 5, characterized in that space occupier particles which are chemically soluble or can be volatilized by means of pyrolysis are added to the molding composition in addition to the polystyrene particles and physically separately therefrom to form micropores in the shaped body.
  8. The process as claimed in any of claims 1 to 5, characterized in that a proportion by volume of cell-forming pores of greater than 30% and less than 85%, based on the volume of the sintered shaped body, is formed on foaming.
  9. The process as claimed in any of claims 1 to 8, characterized in that cell-forming pores having a mean diameter of 0.1 - 10 mm and a proportion of 60 - 85% by volume, based on the state in the sintered shaped body, are produced.
  10. The process as claimed in any of claims 1 to 9, characterized in that the removal of blowing agents and organic components is effected by dissolution of these in organic solvents.
  11. The process as claimed in any of claims 1 to 10, characterized in that the removal of the blowing agent is effected pyrolytically.
  12. The process as claimed in any of claims 1 to 11, characterized in that the shaping and foaming process occurs after an extrusion process.
  13. The process as claimed in any of claims 1 to 12, characterized in that the metal powder selected from the group consisting of Fe, Co, Ni, Cu, Ti, Ta, Mo, W and noble metals is introduced as pure metal, as oxide, nitride and/or hydride into the mixture for the molding composition.
  14. The process as claimed in any of claims 1 to 13, characterized in that the metal powder is introduced in the form of a type of cemented carbide into the mixture for the molding composition.
  15. The process as claimed in any of claims 1 to 14, characterized in that a mixture of various binder components having a predominant proportion by weight of polyamide is used.
EP04705030A 2003-01-30 2004-01-26 Method for producing porous sintered bodies Expired - Lifetime EP1587772B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AT422003U 2003-01-30
AT0004203U AT6727U1 (en) 2003-01-30 2003-01-30 METHOD FOR PRODUCING POROUS SINTERED BODIES
PCT/AT2004/000025 WO2004067476A1 (en) 2003-01-30 2004-01-26 Method for producing porous sintered bodies

Publications (2)

Publication Number Publication Date
EP1587772A1 EP1587772A1 (en) 2005-10-26
EP1587772B1 true EP1587772B1 (en) 2008-08-13

Family

ID=31192710

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04705030A Expired - Lifetime EP1587772B1 (en) 2003-01-30 2004-01-26 Method for producing porous sintered bodies

Country Status (6)

Country Link
US (1) US20060118984A1 (en)
EP (1) EP1587772B1 (en)
JP (1) JP2006516678A (en)
AT (2) AT6727U1 (en)
DE (1) DE502004007830D1 (en)
WO (1) WO2004067476A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009040258A1 (en) 2009-09-04 2011-03-24 Jaeckel, Manfred, Dipl.-Ing. Process for producing a cellular sintered body

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT6556U1 (en) * 2003-02-20 2003-12-29 Plansee Ag METHOD FOR FOAMING SINTER MOLDED BODIES WITH CELL STRUCTURE
AT9339U1 (en) * 2006-07-06 2007-08-15 Plansee Se METHOD FOR PRODUCING AN EXTRUDED FORM BODY
US9447503B2 (en) * 2007-05-30 2016-09-20 United Technologies Corporation Closed pore ceramic composite article
US9242297B2 (en) * 2009-03-30 2016-01-26 Mitsubishi Materials Corporation Process for producing porous sintered aluminum, and porous sintered aluminum
JP5402380B2 (en) 2009-03-30 2014-01-29 三菱マテリアル株式会社 Method for producing porous aluminum sintered body
WO2010139686A1 (en) * 2009-06-02 2010-12-09 Basf Se Method for producing porous metal sintered molded bodies
US9992917B2 (en) 2014-03-10 2018-06-05 Vulcan GMS 3-D printing method for producing tungsten-based shielding parts
US10590529B2 (en) * 2015-11-20 2020-03-17 Fourté International, Sdn. Bhd Metal foams and methods of manufacture
KR20180041343A (en) * 2016-10-14 2018-04-24 주식회사 엘지화학 Preparation method for metal alloy foam
US10822280B2 (en) * 2017-12-15 2020-11-03 Rolls-Royce High Temperature Composites Inc. Method of making a fiber preform for ceramic matrix composite (CMC) fabrication utilizing a fugitive binder

Family Cites Families (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH494197A (en) * 1965-05-26 1970-07-31 Ohno Atsumi Manufacture of porous refractory materials by the
US4517069A (en) * 1982-07-09 1985-05-14 Eltech Systems Corporation Titanium and titanium hydride reticulates and method for making
JPS61132572A (en) * 1984-11-29 1986-06-20 東京窯業株式会社 Manufacture of heat insulating brick
JPS61191573A (en) * 1985-02-15 1986-08-26 呉羽化学工業株式会社 Resin reinforced porous carbon material
JPS62158175A (en) * 1986-01-07 1987-07-14 住友大阪セメント株式会社 Porous ceramic formed body for substitute bone and manufacture
JPH0784538B2 (en) * 1987-05-11 1995-09-13 エヌオーケー株式会社 Method for producing porous body
DE3724156A1 (en) * 1987-07-22 1989-02-02 Norddeutsche Affinerie METHOD FOR PRODUCING METALLIC OR CERAMIC HOLLOW BALLS
JPH01133989A (en) * 1987-11-19 1989-05-26 Toshiba Ceramics Co Ltd Manufacture of porous ceramic
DE4101630A1 (en) * 1990-06-08 1991-12-12 Fraunhofer Ges Forschung METHOD FOR PRODUCING FOAMABLE METAL BODIES AND USE THEREOF
JP2903738B2 (en) * 1991-02-22 1999-06-14 ティーディーケイ株式会社 Radio wave absorber
US5213612A (en) * 1991-10-17 1993-05-25 General Electric Company Method of forming porous bodies of molybdenum or tungsten
US5830305A (en) * 1992-08-11 1998-11-03 E. Khashoggi Industries, Llc Methods of molding articles having an inorganically filled organic polymer matrix
US5506046A (en) * 1992-08-11 1996-04-09 E. Khashoggi Industries Articles of manufacture fashioned from sheets having a highly inorganically filled organic polymer matrix
JPH07130528A (en) * 1993-10-29 1995-05-19 Tokin Corp Manufacture of sintered material of porous soft magnetic ferrite
JPH07291759A (en) * 1994-04-27 1995-11-07 Ngk Spark Plug Co Ltd Production of porous ceramics
DE19648926C1 (en) * 1996-11-26 1998-01-15 Manfred Dipl Ing Jaeckel Moulded body used as screw and kneading element
US6210612B1 (en) * 1997-03-31 2001-04-03 Pouvair Corporation Method for the manufacture of porous ceramic articles
FR2780406B1 (en) * 1998-06-29 2000-08-25 Bp Chem Int Ltd EXPANDABLE POLYSTYRENE COMPOSITION, PROCESS FOR PREPARING THE COMPOSITION AND EXPANDED MATERIALS RESULTING FROM THE COMPOSITION
US6759004B1 (en) * 1999-07-20 2004-07-06 Southco, Inc. Process for forming microporous metal parts
RU2185350C2 (en) * 2000-06-15 2002-07-20 Российский химико-технологический университет им. Д.И. Менделеева Method of manufacture of ceramic articles
JP4572287B2 (en) * 2001-03-23 2010-11-04 独立行政法人産業技術総合研究所 Method for producing high strength porous body and high strength porous body

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009040258A1 (en) 2009-09-04 2011-03-24 Jaeckel, Manfred, Dipl.-Ing. Process for producing a cellular sintered body
EP2679564A1 (en) 2009-09-04 2014-01-01 Manfred Jaeckel Method for producing a cellular sinter mould

Also Published As

Publication number Publication date
AT6727U1 (en) 2004-03-25
DE502004007830D1 (en) 2008-09-25
ATE404506T1 (en) 2008-08-15
WO2004067476A1 (en) 2004-08-12
US20060118984A1 (en) 2006-06-08
JP2006516678A (en) 2006-07-06
EP1587772A1 (en) 2005-10-26

Similar Documents

Publication Publication Date Title
DE10084853B3 (en) Process for producing microporous metal parts
EP1915226B1 (en) Process for the powder metallurgy production of metal foam and of parts made from metal foam
EP0799810B1 (en) Sintered foams with open porosity and continuous process for their preparation
EP0300543B1 (en) Process for the production of hollow metallic or ceramic spheres
DE102008000100B4 (en) A process for producing a lightweight green body, then manufactured lightweight green body and method for producing a lightweight molded article
EP2437905B1 (en) Method for producing porous metallic sintered bodies
EP1587772B1 (en) Method for producing porous sintered bodies
DE69018019T2 (en) METHOD FOR PRODUCING MOLDED BODIES FROM MIXTURES OF HEAT-CURABLE BINDERS AND POWDER WITH DESIRED CHEMICAL PROPERTIES.
EP0907620B1 (en) Method of stabilizing sintered foam and of producing open-cell sintered foam parts
WO2001078923A1 (en) Metallic miniaturized hollow shaped bodies and method for producing shaped bodies of this type
US6254998B1 (en) Cellular structures and processes for making such structures
WO2009050687A2 (en) Method of producing open-cell inorganic foam
DE3736660C2 (en)
EP2679564A1 (en) Method for producing a cellular sinter mould
EP1597004B1 (en) Method for foaming powder-molded bodies comprising a cellular structure
WO2004063406A2 (en) Method for producing metal foam bodies
DE19612985A1 (en) Producing open-celled inorganic sintered foam products
DE1504888C (en) Polymeric, network-structured body and method for producing the same
DE1504888A1 (en) Process for the production of polymer structures with a network structure

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: 20050701

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL LT LV MK

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: PLANSEE GMBH

DAX Request for extension of the european patent (deleted)
RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: PLANSEE SE

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: PLANSEE SE

RIN1 Information on inventor provided before grant (corrected)

Inventor name: JAECKEL, MANFRED

Inventor name: FAERBER, JOERG

17Q First examination report despatched

Effective date: 20051020

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

Free format text: LANGUAGE OF EP DOCUMENT: GERMAN

REF Corresponds to:

Ref document number: 502004007830

Country of ref document: DE

Date of ref document: 20080925

Kind code of ref document: P

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20081124

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

Ref country code: SI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

REG Reference to a national code

Ref country code: IE

Ref legal event code: FD4D

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

Ref country code: BG

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20081113

Ref country code: IE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: RO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

Ref country code: SK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20090113

Ref country code: CZ

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20090514

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: EE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

Ref country code: MC

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20090131

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20090126

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20090131

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20090131

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20091030

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20090126

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20081113

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20090131

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20090202

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20090126

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20081114

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20090126

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: HU

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20090214

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: TR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080813

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20160120

Year of fee payment: 13

REG Reference to a national code

Ref country code: DE

Ref legal event code: R119

Ref document number: 502004007830

Country of ref document: DE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20170801