EP0525325A1 - Process for preparing dense sintered articles - Google Patents
Process for preparing dense sintered articles Download PDFInfo
- Publication number
- EP0525325A1 EP0525325A1 EP92108827A EP92108827A EP0525325A1 EP 0525325 A1 EP0525325 A1 EP 0525325A1 EP 92108827 A EP92108827 A EP 92108827A EP 92108827 A EP92108827 A EP 92108827A EP 0525325 A1 EP0525325 A1 EP 0525325A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- binder
- green body
- mixture
- mold
- powder
- 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.)
- Granted
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 3
- 239000011230 binding agent Substances 0.000 claims abstract description 55
- 239000000203 mixture Substances 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims abstract description 31
- 239000000463 material Substances 0.000 claims abstract description 22
- 239000002904 solvent Substances 0.000 claims abstract description 16
- 238000005266 casting Methods 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 229910010293 ceramic material Inorganic materials 0.000 claims abstract description 5
- 229910052751 metal Inorganic materials 0.000 claims abstract description 5
- 239000002184 metal Substances 0.000 claims abstract description 5
- 230000009969 flowable effect Effects 0.000 claims abstract description 3
- 239000000843 powder Substances 0.000 claims description 17
- 238000005245 sintering Methods 0.000 claims description 11
- 150000001875 compounds Chemical class 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 3
- 238000001513 hot isostatic pressing Methods 0.000 claims description 2
- 239000002245 particle Substances 0.000 description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 10
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 238000011049 filling Methods 0.000 description 6
- 229920001800 Shellac Polymers 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- ZLGIYFNHBLSMPS-ATJNOEHPSA-N shellac Chemical compound OCCCCCC(O)C(O)CCCCCCCC(O)=O.C1C23[C@H](C(O)=O)CCC2[C@](C)(CO)[C@@H]1C(C(O)=O)=C[C@@H]3O ZLGIYFNHBLSMPS-ATJNOEHPSA-N 0.000 description 4
- 239000004208 shellac Substances 0.000 description 4
- 229940113147 shellac Drugs 0.000 description 4
- 235000013874 shellac Nutrition 0.000 description 4
- 238000002156 mixing Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000004809 Teflon Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910000601 superalloy Inorganic materials 0.000 description 2
- 239000001993 wax Substances 0.000 description 2
- 229910001928 zirconium oxide Inorganic materials 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 208000031872 Body Remains Diseases 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000001739 density measurement Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- UGFMBZYKVQSQFX-UHFFFAOYSA-N para-methoxy-n-methylamphetamine Chemical compound CNC(C)CC1=CC=C(OC)C=C1 UGFMBZYKVQSQFX-UHFFFAOYSA-N 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/26—Producing shaped prefabricated articles from the material by slip-casting, i.e. by casting a suspension or dispersion of the material in a liquid-absorbent or porous mould, the liquid being allowed to soak into or pass through the walls of the mould; Moulds therefor ; specially for manufacturing articles starting from a ceramic slip; Moulds therefor
-
- 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
-
- 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 dense sintered workpieces made of metal, a metal alloy or ceramic materials, in which a green body is first formed from a mixture of the metal in powder form, the metal alloy or the ceramic material and a binder, which removes the binder. sintered and the sintered body is compressed, if necessary, by hot isostatic pressing (HIP process).
- HIP process hot isostatic pressing
- a viscous mixture of powder and binder has previously been produced, and this mixture has been pressed into the predetermined shape under a pressure of a few hundred bars. Quite apart from the fact that with this procedure narrow cavities of the form to be filled can be inaccessible to the viscous mass, it also shows that during the subsequent binder removal or Sintering process, to which the viscous mass filled under pressure is subjected, the binder is not completely removed from the mass or. the green body escapes so that undesirable residues can remain in the workpiece.
- This object is achieved in that first the mixture of the powder, the binder, the proportion of which in the mixture is such that it is sufficient to solidify the powder-binder mixture to form the green body and thereby 2 to 5 vol %, and a solvent for the binder is formed so that it is in the form of a flowable, solid, liquid mass (casting mass), after which this mass is poured into the predetermined shape, applied or sprayed on and then dried, the solvent escaping and the remaining binder Powder-binder mixture solidified, so that the green body is formed, which is then debindered and sintered.
- the green body is removed from the mold after drying and is ready for further processing.
- the casting compound is expediently produced in a separate vessel, after which it is poured into the mold through a sprue or a funnel.
- Adequate filling of the form is achieved by gravitation and can be accompanied by targeted vibration of the form. External vibrations and / or rotations of the shape by hand or mechanically are useful for this.
- the solvent can be removed from the mass filled into the mold under normal pressure and at room temperature. However, this drying process can also take place at elevated temperature and / or under a slight negative pressure or can be accelerated thereby.
- the filling can be built up in several steps using different materials.
- a procedure which is expedient for this is that mixtures formed from different materials are poured into the mold one after the other, so that the poured-in mass and thus also the green body formed thereafter consists of layers of different composition arranged one above the other.
- a second is poured onto the first. This process is continued until the mold is completely filled, so that a layer system green body composed of different materials with a stepped structure, e.g. with regard to material, porosity, grain / particle size distribution.
- a further process variant consists in that the mixture is filled in via / or around a green body previously introduced into the mold or an already finished workpiece.
- an inner or outer coating (s) or covering of a solid part that has already been produced can be produced, the casting compound being poured into the cavities and the surface to be coated after being introduced into a suitable mold.
- the casting compound can also be applied or sprayed on with a brush and then further processed with good success.
- Composites or graded materials can be made by inserting the insert component into the premix or by inserting it into the mold prior to casting.
- the general rule is that the proportion of the binder in the mixture should be such that it is sufficient to solidify the mass to form a manageable green body.
- the amount of binder required for this can easily be determined by means of a few preliminary tests; it is in the range between 2 and 5% by volume.
- binder fraction 0.02 (2.00% by volume) with particle sizes of approximately 20 ⁇ m have considerable strength. However, when using larger particles with the same binder content, the strength is still sufficient to ensure that the green bodies are handled safely.
- the proportion of binder can be varied by controlled addition or evaporation of the liquid, volatile solvent component (carrier). In practice, the maximum volume fraction is limited by the solubility limit of the binder in the solvent or by the relative natural porosity, which is approximately 26% for ideally packed spherical particles.
- the binder condenses as a thin film on the powder particles during the removal (evaporation) of the solvent (carrier) and a rapid, continuous removal of the solvent (carrier) through the free particle spaces takes place.
- the final strength of the green body is achieved after the solvent (carrier) has been completely removed and after the binder has solidified at room temperature (possibly also at elevated temperature) as a solid network with connecting bridges between adjacent powder particles.
- the green body After the green body has been formed, it is subjected to a thermally activated debinding and sintering treatment.
- the green body is heated to remove the binder.
- This debinding process is not restricted to a specific time-temperature program (profiles, sequences, cycles), although a few partial steps are required to enable complete binder removal.
- a typical procedure is that the green body is heated at a rate of 3-10 ° C./min to a temperature in the range from 280 to 420 ° C. and, depending on the size of the body, is kept at this temperature until the binder is removed.
- the body is then heated to sintering temperature up to a rate of> 10 ° C / min.
- High temperatures promote the rapid splitting of the binder into a vapor that sublimes outside the green body either in the atmosphere or pumped out by a vacuum system. The splitting and removal takes until the binder has burned out.
- Materials such as super alloys, stainless steel, titanium alloys and aluminum alloys, iron materials, ceramic powders, for example, can be used as the material for the workpieces to be produced.
- Zirconium oxide, chromium oxide, lathan oxide, perovskite, aluminum oxide, silicon oxide can be provided.
- Wax, shellac, PMMA and alcohol, trichlorethylene, toluene (toluene) are mentioned as binders.
- the sintering of the green bodies produced by the process according to the invention was carried out using specific, known schemes for each material. Density measurements showed that the sinterability of the materials is not affected by the process itself.
- the end product can be sintered to a closed porosity. The sintered parts with closed porosity can therefore be compacted containerless up to the theoretical density by HIP.
- Chemical analyzes of end products produced by the method according to the invention showed no increase in the concentration of contaminants related to the chemical composition of the binder, such as oxygen, carbon, nitrogen and hydrogen.
- the overall composition was within the nominal concentrations of the starting products.
- the mixture was poured into a four-part stable Teflon mold, measuring 80x20x1 mm. After 2 hours of drying in air, the product achieved high strength, making handling easy.
- the total process time was 4.27 h.
- the density of the sintered part was 92.5% of the theoretical density of Ti6A14V and the chem. Analysis showed within the measurement accuracy the same composition as that of the starting powder.
- the mixture was applied to the substrate with a brush.
- the 50 ⁇ m thick layer produced in this way was then air-dried for half an hour.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Dispersion Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Powder Metallurgy (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Ceramic Products (AREA)
- Manufacture Of Alloys Or Alloy Compounds (AREA)
Abstract
Description
Die Erfindung bezieht sich auf ein Verfahren zum Herstellen dichter Sinterwerkstücke aus Metall, einer Metalllegierung oder aus keramischen Werkstoffen, bei dem zunächst aus einem Gemisch des als Pulver vorliegenden Metalls, der Metalllegierung oder des keramischen Werkstoffs und einem Binder ein Grünkörper geformt wird, dieser entbindert, gesintert und der Sinterkörper ggfs. durch Heißisostatisches Pressen (HIP-Verfahren) verdichtet wird.The invention relates to a method for producing dense sintered workpieces made of metal, a metal alloy or ceramic materials, in which a green body is first formed from a mixture of the metal in powder form, the metal alloy or the ceramic material and a binder, which removes the binder. sintered and the sintered body is compressed, if necessary, by hot isostatic pressing (HIP process).
Dieses bekannte Verfahren, bei dem der Grünkörper z.B. im Vakuum gesintert und anschließend der HIP-Schritt angewandt wird, dient dazu, Werkstücke annähernd auf ihre theoretisch mögliche Werkstoffdichte zu kompaktieren.This known method in which the green body e.g. Sintered in a vacuum and then using the HIP step serves to compact workpieces approximately to their theoretically possible material density.
Zur Herstellung des Grünkörpers wurde bisher ein viskoses Gemisch aus Pulver und Binder (Wachse und Kunststoffe) hergestellt und dieses Gemisch unter Druck von einigen Hundert Bar in die vorbestimmte Form gepreßt. Ganz abgesehen davon, daß bei dieser Verfahrensweise enge Hohlräume der zu füllenden Form für die viskose Masse unzugänglich sein können, zeigt sich auch, daß beim anschließenden Binderentfernungs-bzw. Sinterungsvorgang, dem die unter Druck in die Form gefüllte viskose Masse unterworfen wird, der Binder nicht vollständig aus der Masse bwz. dem Grünkörper entweicht, so daß unerwünschte Rückstände im Werkstück verbleiben können.To produce the green body, a viscous mixture of powder and binder (waxes and plastics) has previously been produced, and this mixture has been pressed into the predetermined shape under a pressure of a few hundred bars. Quite apart from the fact that with this procedure narrow cavities of the form to be filled can be inaccessible to the viscous mass, it also shows that during the subsequent binder removal or Sintering process, to which the viscous mass filled under pressure is subjected, the binder is not completely removed from the mass or. the green body escapes so that undesirable residues can remain in the workpiece.
Es ist daher Aufgabe der Erfindung, ein Verfahren der eingangs bezeichneten Art zu schaffen, daß die vorgenannten Nachteile weitgehend vermeidet.It is therefore an object of the invention to provide a method of the type described in the opening paragraph which largely avoids the aforementioned disadvantages.
Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß zunächst das Gemisch derart aus dem Pulver, dem Binder, dessen Anteil im Gemisch so bemessen ist, daß er zur Verfestigung des Pulver-Binder-Gemischs zur Bildung des Grünkörpers ausreicht und dabei am Gemisch 2 bis 5 Vol% beträgt, und einem Lösungsmittel für den Binder gebildet wird, daß es als fließfähige, festflüssige Masse (Gießmasse) vorliegt, wonach diese Masse in die vorbestimmte Form gegossen, aufgetragen oder aufgesprayt und anschließend getrocknet wird, wobei das Lösungsmittel entweicht und der verbleibende Binder das Pulver-Binder-Gemisch verfestigt, so daß der Grünkörper gebildet wird, der anschließend entbindert und gesintert wird.This object is achieved in that first the mixture of the powder, the binder, the proportion of which in the mixture is such that it is sufficient to solidify the powder-binder mixture to form the green body and thereby 2 to 5 vol %, and a solvent for the binder is formed so that it is in the form of a flowable, solid, liquid mass (casting mass), after which this mass is poured into the predetermined shape, applied or sprayed on and then dried, the solvent escaping and the remaining binder Powder-binder mixture solidified, so that the green body is formed, which is then debindered and sintered.
Wie sich gezeigt hat, können durch diese erfindungsgemäße Verfahrensweise, die als "Naß-Pulvergießen" bezeichnet werden kann, aus Pulvern verschiedener Materialien und mit verschiedenen Teilchengrößenverteilungen dreidimensionale, endkonturnahe, feste Körper von vorher entworfener Gestalt und/oder Größe geformt werden. Die rheologischen Eigenschaften der Pulver-Träger-Bindermischung vor dem Gießen werden genutzt, um eine freie (durch Gravitation), ggfs. auch erzwungene Formfüllung zu erreichen, wobei nach der Entfernung des Lösungsmittel (während der Trocknung) das Pulver-Bindergemisch sich in einen festen Grünkörper verfestigt, der die Innenkonturen der Form wiedergibt. Zur erzwungenen Formfüllung werden allenfalls Drücke wenig oberhalb Atmosphärendruck eingesetzt.As has been shown, by this procedure according to the invention, which can be called "wet powder casting", three-dimensional, near-net-shape, solid bodies of a previously designed shape and / or size can be formed from powders of different materials and with different particle size distributions. The rheological properties of the powder-carrier-binder mixture before casting are used to achieve a free (by gravitation), possibly also forced mold filling, whereby after the removal of the solvent (during drying) the powder-binder mixture becomes solid Green body solidified, which reflects the inner contours of the shape. At most, pressures slightly above atmospheric pressure are used to force the mold to be filled.
Der Grünkörper wird nach dem Trocknen aus der Form entfernt und ist damit bereit für die weitere Bearbeitung.The green body is removed from the mold after drying and is ready for further processing.
Die Gießmasse wird zweckmäßigerweise in einem separaten Gefäß hergestellt, wonach sie durch einen Einguß oder einen Trichter in die Form gegossen wird.The casting compound is expediently produced in a separate vessel, after which it is poured into the mold through a sprue or a funnel.
Ein ausreichendes Verfüllen der Form wird durch die Gravitation erreicht und kann durch gezielte Erschütterung der Form begleitet werden. Hierzu sind äußere Vibrationen und/oder Rotationen der Form von hand oder mechanisch dienlich.Adequate filling of the form is achieved by gravitation and can be accompanied by targeted vibration of the form. External vibrations and / or rotations of the shape by hand or mechanically are useful for this.
Die Entfernung des Lösungsmittels aus der in die Form gefüllten Masse kann unter Normaldruck und bei Raumtemperatur erfolgen. Dieser Trocknungsvorgang kann aber auch bei erhöhter Temperatur und/oder unter leichtem Unterdruck stattfinden bzw. dadurch beschleunigt werden.The solvent can be removed from the mass filled into the mold under normal pressure and at room temperature. However, this drying process can also take place at elevated temperature and / or under a slight negative pressure or can be accelerated thereby.
Sollen Werkstücke aus unterschiedlichen Schichtungen (gradierte Werkstoffe) hergestellt werden, so kann der Aufbau der Füllung in mehreren Schritten mit unterschiedlichen Materialien erfolgen. Eine hierfür zweckmäßige Verfahrensweise besteht dabei darin, daß aus unterschiedlichen Materialien gebildete Gemische nacheinander in die Form gegoßen werden, so daß die eingegossene Masse und damit auch der danach gebildete Grünkörper aus übereinanderliegend angeordneten Schichten unterschiedlicher Zusammensetzung besteht.If workpieces are to be produced from different layers (graded materials), the filling can be built up in several steps using different materials. A procedure which is expedient for this is that mixtures formed from different materials are poured into the mold one after the other, so that the poured-in mass and thus also the green body formed thereafter consists of layers of different composition arranged one above the other.
Nach dem Eingießen des ersten Materials mit bestimmter Zusammensetzung wird ein zweites auf das erste gegossen. Dieser Prozeß wird bis zur vollständigen Füllung der Form fortgesetzt, so daß ein aus verschiedenen Materialien aufgebauter Schichtsystem-Grünkörper mit einer abgestuften Struktur, z.B. bezüglich Material, Porosität, Korn/Teilchengrößenverteilung, entsteht.After pouring the first material with a certain composition, a second is poured onto the first. This process is continued until the mold is completely filled, so that a layer system green body composed of different materials with a stepped structure, e.g. with regard to material, porosity, grain / particle size distribution.
Eine weitere Verfahrensvariante besteht darin, daß das Gemisch über/oder um einen in die Form vorab eingebrachten Grünkörper oder ein bereits fertiges Werkstück eingefüllt wird.A further process variant consists in that the mixture is filled in via / or around a green body previously introduced into the mold or an already finished workpiece.
Auf diese Weise läßt sich eine innere oder äußere Beschichtung(en) oder Umhüllung eines bereits erzeugten, festen Teils herstellen, wobei nach dem Einbringen in eine geeignete Form die Gießmasse in die Hohlräume und die zu beschichtende Oberfläche gegossen wird.In this way, an inner or outer coating (s) or covering of a solid part that has already been produced can be produced, the casting compound being poured into the cavities and the surface to be coated after being introduced into a suitable mold.
Wie sich gezeigt hat, kann die Gießmasse auch mit einem Pinsel aufgetragen oder aufgesprayt und dann mit gutem Erfolg weiterbehandelt werden.As has been shown, the casting compound can also be applied or sprayed on with a brush and then further processed with good success.
Verbundwerkstoffe bzw. gradierte Werkstoffe können hergestellt werden, indem die Einlagekomponente in die Vormischung eingebracht wird oder indem sie vor dem Gießen in die Form eingebracht wird.Composites or graded materials can be made by inserting the insert component into the premix or by inserting it into the mold prior to casting.
Die erzielte Festigkeit des Grünkörpers hängt im allgemeinen von 2 Parametern ab:
- a. vom relativen Volumenanteil des Binders im Grünkörpers und
- b. von der mittleren Teilchengröße des verwendeten Pulvers.
- a. of the relative volume fraction of the binder in the green body and
- b. from the average particle size of the powder used.
Generelle Regel ist dabei, daß der Anteil des Binders im Gemisch so zu bemessen ist, daß er gerade zur Verfestigung der Masse zur Bildung eines handhabbaren Grünkörpers ausreicht. Die hierzu erforderliche Menge des Binders ist leicht durch einige Vorversuche zu ermitteln, sie liegt im Bereich zwischen 2 und 5 Vol%.The general rule is that the proportion of the binder in the mixture should be such that it is sufficient to solidify the mass to form a manageable green body. The amount of binder required for this can easily be determined by means of a few preliminary tests; it is in the range between 2 and 5% by volume.
Wie sich gezeigt hat, haben Grünkörper mit einem Binderanteil von 0,02 (2,00 Vol%) mit Teilchengrößen von ca. 20 um eine beachtliche Festigkeit. Bei der Verwendung von größeren Teilchen mit demselben Binderanteil ist die Festigkeit jedoch immer noch hinreichend, um ein sicheres Handhaben der Grünkörper zu gewährleisten. Der Binderanteil läßt sich durch kontrolliertes Hinzufügen oder Verdampfen des flüssigen, flüchtigen Lösungsmittel-Bestandteils (Träger) variieren. In der Praxis wird der maximale Volumenanteil durch die Löslichkeitsgrenze des Binders im Lösungsmittel oder durch die relative natürliche Porosität begrenzt, die ungefähr 26 % bei ideal gepackten Kugelteilchen beträgt.As has been shown, green bodies with a binder fraction of 0.02 (2.00% by volume) with particle sizes of approximately 20 μm have considerable strength. However, when using larger particles with the same binder content, the strength is still sufficient to ensure that the green bodies are handled safely. The proportion of binder can be varied by controlled addition or evaporation of the liquid, volatile solvent component (carrier). In practice, the maximum volume fraction is limited by the solubility limit of the binder in the solvent or by the relative natural porosity, which is approximately 26% for ideally packed spherical particles.
Da das erfindungsgemäße Verfahren nur verhälnismäßig kleine Bindermengen (2 - 5 Vol.%) verwendet, ist nur ein Teil des Raumes zwischen den Teilchen von Binder erfüllt. Deshalb kondensiert der Binder während der Entfernung (Verdampfung) des Lösungsmittels (Trägers) als dünner Film auf den Pulverteilchen und eine schnelle, kontinuierliche Entfernung des Lösungsmittels (Trägers) durch die freien Teilchenzwischenräume findet statt.Since the method according to the invention uses only relatively small amounts of binder (2-5% by volume), only part of the space between the particles of binder is fulfilled. Therefore, the binder condenses as a thin film on the powder particles during the removal (evaporation) of the solvent (carrier) and a rapid, continuous removal of the solvent (carrier) through the free particle spaces takes place.
Die Endfestigkeit des Grünkörpers wird erreicht nach der vollständigen Entfernung des Lösungsmittels (Trägers) und nach dem Festwerden des Binders bei Raumtemperatur (ggfs. auch bei erhöhter Temperatur) als festes Netzwerk mit Verbindungsbrücken zwischen benachbarten Pulverteilchen.The final strength of the green body is achieved after the solvent (carrier) has been completely removed and after the binder has solidified at room temperature (possibly also at elevated temperature) as a solid network with connecting bridges between adjacent powder particles.
Die Tatsache, daß die Bindung der Pulverteilchen, eines mit dem anderen, durch die Bildung von lokalen Brücken gewährleistet wird, ist nicht nur vorteilhaft für die Entfernung der Lösungsmittel, sondern ist auch für den anschließenden Prozeß der Sinterung von großer Bedeutung.The fact that the binding of the powder particles, one with the other, is ensured by the formation of local bridges is not only advantageous for the removal of the solvents, but is also of great importance for the subsequent sintering process.
Nach Bildung des Grünkörpers wird dieser einer thermisch aktivierten Entbinderungs- und Sinterbehandlung unterzogen. Dabei wird der Grünkörper zur Entfernung des Binders erhitzt. Dieser Entbinderungsprozeß ist nicht auf ein bestimmtes Zeit-Temperatur-Programm beschränkt (Profile, Zeifolgen, Zyklen), obwohl einige Teilschritte erforderlich sind, um eine vollständige Binderentfernung zu ermöglichen. Eine typische Verfahrensweise besteht darin, daß die Grünkörper mit einer Rate von 3 - 10°C/min auf eine Temperatur im Bereich von 280 bis 420 ° C aufgeheizt und je nach der Größe des Körpers auf dieser Temperatur bis zur Entfernung des Binders gehalten wird. Anschließend wird der Körper auf Sintertemperatur bis mit einer Rate von > 10°C/min aufgeheizt.After the green body has been formed, it is subjected to a thermally activated debinding and sintering treatment. The green body is heated to remove the binder. This debinding process is not restricted to a specific time-temperature program (profiles, sequences, cycles), although a few partial steps are required to enable complete binder removal. A typical procedure is that the green body is heated at a rate of 3-10 ° C./min to a temperature in the range from 280 to 420 ° C. and, depending on the size of the body, is kept at this temperature until the binder is removed. The body is then heated to sintering temperature up to a rate of> 10 ° C / min.
Die besten Entbinderungsergebnisse erhält man in der Regel unter Fein- bis Hochvakuumbedingungen, wenn auch ein beachtlicher Entwachsungsumfang bei Atmosphärendruck oder leichtem Vakuum stattfindet. Eine Entbinderung unter strömender Gasatmosphäre ist ebenso möglich.The best debinding results are usually obtained under fine to high vacuum conditions, although there is a considerable amount of dewaxing at atmospheric pressure or a light vacuum. Debinding under a flowing gas atmosphere is also possible.
Die Unemfpindlichkeit des Entbinderungsprozesses auf den speziellen thermischen Zyklus als auch die Möglichkeit relativ hohe Heizraten zu verwenden liegt primär an zwei Faktoren:
- a. der geringe Volumenanteil des Binders hat eine offene Struktur zwischen den Teilchen zur Folge. Diese gewährleistet für die Dämpfe, die von dem sich zersetzenden Binder stammen, einen unbehinderten Weg aus dem Grünkörper. b. die intrinsichen Eigenschaften des Binders, der, wenn er über den Schmelzpunkt erhitzt wird, in ein hoch-viskoses Produkt polymerisiert, so daß die netzwerkartige Struktur zwischen den Teilchen und die damit verbundene Form des Grünkörpers bestehen bleibt.
- a. the low volume fraction of the binder results in an open structure between the particles. This guarantees an unobstructed path out of the green body for the vapors that come from the decomposing binder. b. the intrinsic properties of the binder, which, when heated above the melting point, polymerizes into a highly viscous product, so that the network-like structure between the particles and the associated shape of the green body remains.
Hohe Temperaturen fördern das schnelle Aufspalten des Binders in einen Dampf, der außerhalb des Grünkörpers entweder in der Atmosphäre oder abgepumpt von einem Vakuumsystem sublimiert. Das Aufspalten und Entfernen dauert so lange, bis der Binder herausgebrannt ist.High temperatures promote the rapid splitting of the binder into a vapor that sublimes outside the green body either in the atmosphere or pumped out by a vacuum system. The splitting and removal takes until the binder has burned out.
Die Tatsache, daß die Festigkeit des entbinderten Grünkörpers ausreichend ist, um eine weitere Handhabbarkeit zu gewährleisten, liegt an möglichen Binder-Spaltungsrückständen, die die Pulverteilchen in der jeweiligen Lage halten.The fact that the strength of the debindered green body is sufficient to ensure further manageability is due to possible binder cleavage residues which hold the powder particles in the respective position.
Als Material für die herzustellenden Werkstükke können Materialien, wie Superlegierungen, Edelstahl, Titanlegierungen und Aluminiumlegierungen, Eisenwerkstoffe, keramische Pulver z.B. Zirkonoxid, Chromoxid, Lathanoxid, Perovskite, Aluminiumoxid, Siliziumoxid vorgesehen werden. Als Binder sind Wachs, Schellak, PMMA und als Lösungsmittel Alkohol, Trichlorethylen, Toluen (Toluol) zu nennen.Materials such as super alloys, stainless steel, titanium alloys and aluminum alloys, iron materials, ceramic powders, for example, can be used as the material for the workpieces to be produced. Zirconium oxide, chromium oxide, lathan oxide, perovskite, aluminum oxide, silicon oxide can be provided. Wax, shellac, PMMA and alcohol, trichlorethylene, toluene (toluene) are mentioned as binders.
Das Sintern der nach dem erfindungsgemäßen Verfahren hergestellten Grünkörper wurde unter Verwendung von spezifischen, bekannten Schemen für jedes Material durchgeführt. Dichtemessungen zeigten, daß die Sinterfähigkeit der Materialien nicht vom Verfahren selbst beeinflußt wird. Das Endprodukt kann bis zur geschlossenen Porosität gesintert werden. Die gesinterten Teile mit geschlossener Porosität können deshalb containerlos bis zur theoretischen Dichte durch HIP kompaktiert werden.The sintering of the green bodies produced by the process according to the invention was carried out using specific, known schemes for each material. Density measurements showed that the sinterability of the materials is not affected by the process itself. The end product can be sintered to a closed porosity. The sintered parts with closed porosity can therefore be compacted containerless up to the theoretical density by HIP.
Chemische Analysen von Endprodukten, die nach dem erfindungsgemäßen Verfahren erzeugt wurden, zeigten keinen Konzentrationsanstieg von Veruneinigungselementen die mit der chemischen Zusammensetzung des Binders in Verbindung standen, wie Sauerstoff, Kohlenstoff, Stickstoff und Wasserstoff. Die gesamte Zusammensetzung lag im Rahmen der nominellen Konzentrationen der Ausgangsprodukte.Chemical analyzes of end products produced by the method according to the invention showed no increase in the concentration of contaminants related to the chemical composition of the binder, such as oxygen, carbon, nitrogen and hydrogen. The overall composition was within the nominal concentrations of the starting products.
-
1. Werkstoff Pulver:
- Ni-Basis-Superlegierung (2.4636)
- Teilchengröße: 100 um
- Masse: 100 g
- Volumen: 12,6 ml (berechnet aus der theor.
- Dichte)
- Lösungsmittel
- (Träger): Alkohol (Ethanol)
- Volumen (20 °C): 50 ml
- Masse: 39,5g
- Binder:
- Schellack
- Masse: 2g
- Volumen: 1,8 ml (berechnet)
- Gewichtsanteil Binder:
- 0,014 (1.4 %)
- Volumenanteil Binder:
- 0,028 (2.8 %)
- Ni-based superalloy (2.4636)
- Particle size: 100 µm
- Weight: 100 g
- Volume: 12.6 ml (calculated from the theor.
- Density)
- solvent
- (Carrier): alcohol (ethanol)
- Volume (20 ° C): 50 ml
- Weight: 39.5g
- Binder:
- shellac
- Weight: 2g
- Volume: 1.8 ml (calculated)
- Binder weight fraction:
- 0.014 (1.4%)
- Binder volume fraction:
- 0.028 (2.8%)
-
2. Mischung der Komponenten
Die Werkstoffe wurden in einem Taumelmischer für 2 Stunden gemischt.2. Mixing the components
The materials were mixed in a tumble mixer for 2 hours. -
3. Gießen (Formfüllung) und Trocknung
Die Mischung wurde in eine zweiteilige stabile Teflonform gegossen, die aus zwei exzentrisch zueinander angeordneten Zylindern (20 und 10 mm φ und 10 bzw. 15 mm Länge) bestand. Das Produkt erreichte nach 14 h Trockenzeit in der Luft oder nach 4 h Trocknung im Exsikkator hohe Festigkeit, so daß die Handhabung gut möglich ist.3. Pouring (mold filling) and drying
The mixture was poured into a two-part stable Teflon mold, which consisted of two eccentrically arranged cylinders (20 and 10 mm φ and 10 or 15 mm in length). The product reached high strength after 14 hours of drying time in the air or after 4 hours of drying in a desiccator, so that handling is easy. -
4. Entbinderung und Sinterung Entbinderung und Sinterung wurden im selben Ofen in einem kontinuierlichen Zyklus folgendermaßen durchgeführt:
- 1) Aufheizen von Raumtemperatur auf 350°C mit 3 ° C/min (1,9h).
- 2) Halten bei 350 °C für 3 h.
- 3) Aufheizen von 350°C auf 900°C mit 10 ° C/min (0,9 h).
- 4) Halten bei 900 °C für 3 h.
- 5) Aufheizen von 900°C auf 1265°C mit 10 ° C/min (0,6 h).
- 6) Halten bei 1265°C für 3 h.
- 1) Heating from room temperature to 350 ° C at 3 ° C / min (1.9h).
- 2) Hold at 350 ° C for 3 h.
- 3) Heating from 350 ° C to 900 ° C at 10 ° C / min (0.9 h).
- 4) Hold at 900 ° C for 3 h.
- 5) Heating from 900 ° C to 1265 ° C at 10 ° C / min (0.6 h).
- 6) Hold at 1265 ° C for 3 h.
-
5. Dichte und chem. Analyse
Die Dichte des gesinterten Teiles war 96 % der theor. Dichte (Archimedische Methode) des Werkstoffes und die chem. Analyse erbrachte keine Abweichung von der Nominalzusammensetzung dieses Werkstoffes. Ausführungsbeispiel Nr. 25. Density and chem. analysis
The density of the sintered part was 96% of the theoretical density (Archimedean method) of the material and the chem. Analysis showed no deviation from the nominal composition of this material. Embodiment 2 -
1. Werkstoff
- Pulver:
- Ti6A14V
- Teilchengröße: +53 -180 um
- Masse: 275 g
- Volumen: 62.2 ml (berechnet aus der theor.
- Dichte)
- Lösungmittel (Träger):
- Alkohol (Ethanol)
- Volumen (20 °C): 50 ml
- Masse: 39.5 g
- Binder:
- Schellak
- Masse: 3g
- Volumen: 2.75 ml (berechnet)
- Gewichtsanteil Binder:
- 0,009 (0.9 %)
- Volumenanteil Binder:
- 0,027 (2.7 %)
- Powder:
- Ti6A14V
- Particle size: +53-180 µm
- Weight: 275 g
- Volume: 62.2 ml (calculated from the theor.
- Density)
- Solvent (carrier):
- Alcohol (ethanol)
- Volume (20 ° C): 50 ml
- Weight: 39.5 g
- Binder:
- Shellac
- Weight: 3g
- Volume: 2.75 ml (calculated)
- Binder weight fraction:
- 0.009 (0.9%)
- Binder volume fraction:
- 0.027 (2.7%)
-
2. Mischung der Komponenten
Wie 2. in Ausführungsbeispiel Nr. 12. Mixing the components
Like 2nd in embodiment no. 1 - 3. Gießen (Formfüllung) und Trocknung3. Pouring (mold filling) and drying
Die Mischung wurde in eine vierteilige stabile Teflonform gegossen, mit den Maßen 80x20x1 mm. Das Produkt erreichte nach 2 h Trockenzeit in Luft hohe Festigkeit, so daß Handhabung gut möglich ist.The mixture was poured into a four-part stable Teflon mold, measuring 80x20x1 mm. After 2 hours of drying in air, the product achieved high strength, making handling easy.
4. Entbinderung und Sinterung
- 1) Aufheizen von Raumtemperatur auf 350°C mit 25 ° C/min (0,22 h).
- 2) Halten bei 350 °C für 1 h.
- 3) Aufheizen von 350°C auf 1100°C mit 100°C /min (0,12 h).
- 4) Halten bei 1100°C für 20 Minuten (0,33 h).
- 5) Argonfüllung auf 400 mbar Druck.
- 6) Aufheizen von 1100°C auf 1600°C mit 100 ° C/min (0,1 h).
- 7) Halten bei 1600°C für 2,5 h.
- 1) Heating from room temperature to 350 ° C at 25 ° C / min (0.22 h).
- 2) Hold at 350 ° C for 1 h.
- 3) Heating from 350 ° C to 1100 ° C at 100 ° C / min (0.12 h).
- 4) Hold at 1100 ° C for 20 minutes (0.33 h).
- 5) Argon filling at 400 mbar pressure.
- 6) Heating from 1100 ° C to 1600 ° C at 100 ° C / min (0.1 h).
- 7) Hold at 1600 ° C for 2.5 h.
Die Gesamtprozeßzeit betrug 4.27 h.The total process time was 4.27 h.
5. Dichte und chem. Analyse5. Density and chem. analysis
Die Dichte des gesinterten Teiles war 92,5 % der theor. Dichte von Ti6A14V un die chem. Analyse ergab im Rahmen der Meßgenauigkeit die gleiche Zusammensetzung wie die des Ausgangspulvers.The density of the sintered part was 92.5% of the theoretical density of Ti6A14V and the chem. Analysis showed within the measurement accuracy the same composition as that of the starting powder.
-
1. Werkstoff Pulver:
- Perovskite Lao.84 Sro.16 Mn03
- Teilchengröße: +45 -90 um
- Masse: 25 g
- Lösungsmittel:
- Alkohol (Ethanol)
- Volumen 25 ml
- Binder.
- Schellack
- Masse: 0.5 g
- Substratdichte: Zr02-8Y Folie
- 40 mm φ.
- Perovskite La o . 84 Sr o . 16 Mn0 3
- Particle size: +45 -90 µm
- Weight: 25 g
- Solvent:
- Alcohol (ethanol)
- Volume 25 ml
- Binder.
- shellac
- Weight: 0.5 g
- Substrate density: Zr0 2 -8Y film
- 40 mm φ.
-
2. Mischung der Komponenten
Wie 2 in Ausführungsbeispiel Nr. 1 und Nr. 22. Mixing the components
Like 2 in working example No. 1 and No. 2 - 3. Anwendung der Mischung und Trocknung3. Application of the mixture and drying
Die Mischung wurde mit einer Bürste auf das Substrat aufgebracht. Die hierdurch erzeugte ca. 50 µm dicke Schicht wurde anschließend eine halbe Stunde an der Luft getrocknet.The mixture was applied to the substrate with a brush. The 50 µm thick layer produced in this way was then air-dried for half an hour.
Enbinderung und Sinterung wurden im selben Ofen in einem kontinuierlichen Zyklus folgendermaßen durchgeführt:
- 1) Aufheizen von Raumtemperatur auf 350°C mit 1 ° C/min (5.7 h)
- 2) Halten bei 350 °C für 2 h.
- 3) Aufheizen vo 350 ° C auf 1500 ° C mit 1 ° C/min (19.2 h)
- 4) Halten bei 350 °C für 5 h.
- 5. Ergebnis
- 1) Heating from room temperature to 350 ° C at 1 ° C / min (5.7 h)
- 2) Hold at 350 ° C for 2 h.
- 3) Heating from 350 ° C to 1500 ° C at 1 ° C / min (19.2 h)
- 4) Hold at 350 ° C for 5 h.
- 5. Result
Metallopraphische Analyse der hergestellten Perovskiteschicht ergab eine deutlich sichtbare Haftung zum Zirkonoxidsubstrat. Außerdem konnte eine gleichmäßige poröse Struktur mit ausgeprägter Teilchenverbindung festgestellt werden.Metallographic analysis of the perovskite layer produced showed clearly visible adhesion to the zirconium oxide substrate. In addition, a uniform porous structure with a pronounced particle connection was found.
Claims (9)
dadurch gekennzeichnet,
daß zunächst das Gemisch derart aus dem Pulver, dem Binder, dessen Anteil im Gemisch so bemessen ist, daß er zur Verfestigung des Pulver-Binder-Gemischs zur Bildung des Grünkörpers ausreicht und dabei am Gemisch 2 bis 5 Vol% beträgt, und einem Lösungsmittel für den Binder gebildet wird, daß es als fließfähige, festflüssige Masse (Gießmasse) vorliegt, wonach diese Masse in die vorbestimmte Form gegossen, aufgetragen oder aufgesprayt und anschließend getrocknet wird, wobei das Lösungsmittel entweicht und der verbleibende Binder das Pulver-Binder-Gemisch verfestigt, so daß der Grünkörper gebildet wird, der anschließend entbindert und gesintert wird.1. A method for producing dense sintered workpieces made of metal, a metal alloy or ceramic materials, in which a green body is first formed from a mixture of the metal present in powder form, the metal alloy or the ceramic material and a binder, which debinders, sintered and the sintered body if necessary, compacted by hot isostatic pressing (HIP process),
characterized,
that first the mixture of the powder, the binder, the proportion of which in the mixture is such that it is sufficient to solidify the powder-binder mixture to form the green body and is 2 to 5% by volume of the mixture, and a solvent for the binder is formed so that it is in the form of a flowable, solid, liquid mass (casting mass), after which this mass is poured into the predetermined shape, applied or sprayed on and then dried, the solvent escaping and the remaining binder solidifying the powder-binder mixture, so that the green body is formed, which is then debindered and sintered.
dadurch gekennzeichnet,
daß die Masse unter gleichzeitiger gezielter Erschütterung der Form in diese eingeführt wird.2. The method according to claim 1,
characterized,
that the mass is introduced into this while simultaneously shaking the form in a targeted manner.
dadurch gekennzeichnet,
daß die in der Form befindliche Gießmasse während des Trocknens einem Unterdruck ausgesetzt wird.3. The method according to claim 1 or 2,
characterized,
that the casting compound in the mold is exposed to a negative pressure during drying.
dadurch gekennzeichnet,
daß die in der Form befindliche Gießmasse während des Trocknens temperiert wird.4. The method according to any one of claims 1 to 3,
characterized,
that the casting compound in the mold is tempered during drying.
dadurch gekennzeichnet, daß aus unterschiedlichen Materialien gebildete Gemische nacheinander in die Form gegossen werden, so daß die Gießmasse und damit auch der anschließend gebildete Grünkörper aus übereinanderliegenden Schichten unterschiedlicher Zusammensetzung besteht.5. The method according to any one of claims 1 to 4,
characterized, that mixtures formed from different materials are poured into the mold one after the other, so that the casting compound and thus also the subsequently formed green body consist of layers of different composition lying one above the other.
dadurch gekennzeichnet,
daß das Gemisch über/oder um einen in die Form vorab eingebrachten Grünkörper oder ein bereits fertiges Werkstück eingefüllt wird.6. The method according to any one of claims 1 to 5,
characterized,
that the mixture is filled in via / or around a green body previously introduced into the mold or an already finished workpiece.
dadurch gekennzeichnet,
daß der Grünkörper mit einer Rate von 3 bis 10°C/min auf eine Temperatur im Bereich von 280 bis 420°C aufgeheizt und je nach der Größe des gebildeten Körpers auf dieser Temperatur bis zur Entfernung des Binders gehalten wird.7. The method according to any one of claims 1 to 6,
characterized,
that the green body is heated at a rate of 3 to 10 ° C / min to a temperature in the range from 280 to 420 ° C and, depending on the size of the body formed, is kept at this temperature until the binder is removed.
dadurch gekennzeichnet,
daß der Grünkörper anschließend auf eine Sintertemperatur mit einer Rate von > 10°C /min aufgeheizt wird.8. The method according to claim 7,
characterized,
that the green body is then heated to a sintering temperature at a rate of> 10 ° C / min.
dadurch gekennzeichnet,
daß die Ausheizung unter Fein- bis Hochvakuumbedingungen erfolgt.9. The method according to any one of claims 1 to 8,
characterized,
that the heating takes place under fine to high vacuum conditions.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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DE4120706A DE4120706C2 (en) | 1991-06-22 | 1991-06-22 | Process for the production of porous or dense sintered workpieces |
DE4120706 | 1991-06-22 |
Publications (2)
Publication Number | Publication Date |
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EP0525325A1 true EP0525325A1 (en) | 1993-02-03 |
EP0525325B1 EP0525325B1 (en) | 1996-03-06 |
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EP (1) | EP0525325B1 (en) |
AT (1) | ATE134922T1 (en) |
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DE4037258A1 (en) * | 1989-11-24 | 1991-05-29 | Asea Brown Boveri | Complicated metal or ceramic component prodn. - by vacuum slip casting of thixotropic powder slip |
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US5006493A (en) * | 1986-03-31 | 1991-04-09 | The Dow Chemical Company | Novel ceramic binder comprising poly(ethyloxazoline) |
US4882110A (en) * | 1987-01-27 | 1989-11-21 | Air Products And Chemicals, Inc. | CO2 copolymer binder for forming ceramic bodies and a shaping process using the same |
-
1991
- 1991-06-22 DE DE4120706A patent/DE4120706C2/en not_active Expired - Lifetime
-
1992
- 1992-05-26 AT AT92108827T patent/ATE134922T1/en active
- 1992-05-26 EP EP92108827A patent/EP0525325B1/en not_active Expired - Lifetime
- 1992-05-26 DE DE59205549T patent/DE59205549D1/en not_active Expired - Lifetime
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US4491559A (en) * | 1979-12-31 | 1985-01-01 | Kennametal Inc. | Flowable composition adapted for sintering and method of making |
EP0177209A2 (en) * | 1984-10-01 | 1986-04-09 | CDP, Ltd. | Consolidation of a part from separate metallic components |
EP0260101A2 (en) * | 1986-09-09 | 1988-03-16 | Mixalloy Limited | Production of flat products from particulate material |
WO1988007901A1 (en) * | 1987-04-09 | 1988-10-20 | Ceramic Systems Corporation | Molding and precision forming using highly loaded systems |
DE4037258A1 (en) * | 1989-11-24 | 1991-05-29 | Asea Brown Boveri | Complicated metal or ceramic component prodn. - by vacuum slip casting of thixotropic powder slip |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6652804B1 (en) | 1998-04-17 | 2003-11-25 | Gkn Sinter Metals Gmbh | Method for producing an openly porous sintered metal film |
DE10027551A1 (en) * | 2000-06-02 | 2001-12-13 | Thomas Hesse | Porous or solid product molding process, in which a non-melting powder, solvent and beeswax binder are formed below the wax melting point |
DE10027551B4 (en) * | 2000-06-02 | 2005-09-29 | Hesse, Thomas, Dipl.-Ing. | Process for the production of moldings from a plastically processable molding composition based on beeswax, solvents and sinterable powders and a use of the molding composition |
Also Published As
Publication number | Publication date |
---|---|
EP0525325B1 (en) | 1996-03-06 |
DE4120706C2 (en) | 1994-10-13 |
DE59205549D1 (en) | 1996-04-11 |
ATE134922T1 (en) | 1996-03-15 |
DE4120706A1 (en) | 1992-12-24 |
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