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
  • B22F3/20—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by extruding
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
  • C22C1/0408—Light metal alloys
  • C22C1/0416—Aluminium-based alloys
• • 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
  • B22F3/20—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by extruding
  • B22F2003/206—Hydrostatic or hydraulic extrusion
• • 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
  • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
  • B22F2005/001—Cutting tools, earth boring or grinding tool other than table ware
• • 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
• • 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
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

• the invention relates to sintered metal parts with a homogeneous distribution of non-homogeneously melting components, in the wstl. from non-homogeneous melting non-ferrum metal powder mixtures and processes for their production.
• non-ferrum also means metal mixtures which contain iron in small amounts, up to about 8% by weight - smaller amounts of iron than alloy additives should be possible.
• Hot isostatic pressing Hot Isostatic Pressing
• isostatic pressing Cold Isostatic Pressing
• hot sintering hot isostatic pressing
• All of these methods avoid a complete melting of the metal powder mixture, since separation phenomena would otherwise occur.
• HIP and CIP the parts have to be sintered discontinuously individually in pressure chambers, which is only acceptable for series production in exceptional cases.
• the powder, granulate, semolina or the like to be sintered is generally pressed uniaxially together with pressing aids in near-net shape and the green body thus produced in a sintering furnace at temperatures at 2/3 to 4/5 of the melting or sol Dust temperature of the metal powder, if necessary under a protective atmosphere, sintered.
• powder forging Another known technique for compacting metal powder is powder forging. It is also a discontinuous process in which individual parts are produced in dies.
• Multi-phase powders and powder mixtures are generally sintered near the melting or solidus temperature of the lowest melting component of the mixture.
• Sintering temperature often takes place under a protective gas atmosphere.
• This actual compression of the green part was followed by a heat treatment which improves the structure thus formed.
• This is often followed by post-processing or calibration, in which the sintered parts are brought into their final shape.
• these additional work steps are cost-intensive and complex to integrate into a production line.
• the sintered parts of non-homogeneously melting metal mixtures produced by known processes especially if non-homogeneously melting powder mixtures were sintered, often had porous or segregated areas due to the different diffusion speed of the elements, in which individual phases of the immiscible components crystallize inhomogeneously. This permanently disrupts the sintered structure and its mechanical-technological properties.
• the properties of the powder-sintered parts produced in this way were consequently worsened by these interfering areas, the occurrence of which was unpredictable, and there were large differences in individually produced interfaces, which resulted, for example, in an increased tendency to material cracks along the inhomogeneous areas and a reduced elasticity as a result showed.
• the task is performed by a sintered metal part with a homogeneous distribution of non-homogeneously melting components, in the wstl. from non-homogeneous melting non-ferrum metal powder mixtures, can be produced by: continuous isostatic pressure sintering at temperatures up to about 70% of the melting point of the main Part of the metal powder starting mixture by a die under conditions that avoid the occurrence of a liquid phase in the powder, with formation of a near-net shape sintered profile.
• the invention relates to methods for producing a near-net shape sintered metal part, characterized by: producing a powder compact not close to the net contour, continuous isostatic pressure sintering at a pressure according to the formula
• Pressure sintering temperature and D indicates the relative density of the cold isostatically pre-pressed starting product.
• the relative density is the quotient of the absolute density of the pre-pressed starting product p 0 and the density of the solid alloy p B.
• the pressure sintering process takes place through a die open on one side to form a sintered profile; if necessary, separating the sintered profile into sintered products, heat treating the sintered products or the sintered profile and, if necessary, reworking them.
• the typical continuous isostatic pressure sintering at temperatures up to about 70% of the melting point of the main constituent of the metal powder starting mixture is preferably carried out on a hydraulic extrusion press which is adapted to the process parameters - the usual extrusion which is carried out with homogeneously melting materials at temperatures in the vicinity of the melting point, due to excessive heating of the press strand leads to few dimensionally stable product strands which then have to be further processed, for example by pressing, forging etc.
• the continuous isostatic pressure sintering used here at very high pressures according to the above formula additionally allows a temperature to be selected in which the Heating of the press strand due to friction is also taken into account.
• the actual The preheating temperature T v of the geCIPten starting material is determined using the following formula:
• T means the temperature for the selected hot stretching limit of the material
• Q B the amount of heat supplied to the starting material
• Q ⁇ the amount of heat given off to the tool surface
• 1 the active tool length
• c B the compression speed
• the process is characterized in that the powder material is only slightly and briefly heated due to the possible reduction in the preheating temperature - in contrast to conventional extrusion molding, in which continuous and higher heating of the pressed material is desired.
• a powder compact is preferably used as a starting material for continuous isostatic pressing, by known pressing methods for powder compaction, without lubricants, lubricants or sintering aids.
• This powder compact can already have an inhomogeneous material distribution - in particular if inhomogeneous sintered parts - that is to say composite parts - are to be produced.
• Typical is e.g. an outer material layer made of another, chemically or physically more resistant material - if, for example, a certain corrosion behavior is required in an outer or inner layer - as with powder metallurgical pipes or washers.
• the powder compact is then isostatically pressed / sintered relatively cold in a press with a die and undergoes a bonding reaction at the grain boundaries of the constituents due to the shear forces during the pressing, without a liquid phase which could cause segregation to occur. In this way, a homogeneous sintered product with superior material properties can be obtained.
• this continuously produced sintered product formed by the die can be cooled by controlled cooling, for example by spraying with water, in such a way that a fine crystalline state is generated by quenching or that a defined heat treatment, for example in the case of aluminum alloys, can be carried out using a T4 heat treatment ,
• the cooled strand can be reworked mechanically.
• the 'continuously produced profile-like sintered product is usually separated at product height - by sawing, water jet cutting, laser cutting or other methods familiar to the person skilled in the art. These sections of defined length of the continuously produced sintered product can then be used as such or after finishing - such as surface treatment or calibration.
• the sintered part cut to length in this way can also be subjected to heat treatment if necessary in order to change or temper the material structure.
• the heat treatment must be designed so that no liquid phases can arise.
• a typical post-processing of the sintered product according to the invention is calibration on a press in order to obtain the dimensionally very tightly tolerated final shape of the product. Machining or "machining" is usually not necessary.
• the product sintered at temperatures up to 70% of the melting point of the main constituent already has a finished final contour - this means that the post-treatment steps require little effort.
• the sintered parts produced according to the invention from metal mixtures which do not melt homogeneously show better machinability and higher ductility and higher elongation than those which were produced using methods according to the prior art. This can be seen in the further production process in the better reworkability.
• the mechanical, technological characteristics of the sintered parts, the elasticity, tensile strength and elongation are influenced very favorably.
• a pressure-free sintered component made of an aluminum alloy with 13% by weight silicon has an elongation at break of less than 0.5%, while a component made of the same alloy, which was produced by the method according to the invention, has typical values in the elongation at break of 7 to Has 12%.
• the scatter of the material parameters of sintered parts produced according to the invention is very much smaller than that of hot sintered parts of the same composition - that is, they have narrower material value limits than is the case with conventional HIP or hot sintering.
• immiscible constituents such as hard phases
• the material powder used is a powder mixture of metals or their alloys and other materials such as hard parts, fibers or wear carriers such as boron carbide, BN.
• metal matrix composites can be produced (metal matrix composite), the second component being fibrous or particulate.
• Short or long fibers or particles in proportions of between 5 and 30% by volume can be added as fibers.
• Short fibers or whiskers have a length that is west. is less than 100 times the fiber diameter.
• Long, endless or continuous fibers are those whose fiber length is greater than 100 times their diameter. Fibers can serve to improve the strength of the sintered parts.
• Particle reinforced materials can also be produced in this way. So those with SiC, boron carbide etc.
• Ti alloys such as. Ti / Nb alloys, TiAl, and TiAl Nb as well as Co-Ti-B Mg + SiC, boron carbide, AI2O3 or AIPb alloys with high heat storage capacity that cannot be produced by melt metallurgy - i.e. sintered composite material parts are processed continuously or beryllium parts - magnesium parts, etc.
• Typical compositions are, for example, aluminum with Si, Mg, Cu, Zn and possibly Fe, for example with 10 - 40% Si, Mg 0-3%, Cu 0-5%, Zn and Fe 0-7% as well as other light metal alloys, such as those of magnesium, calcium,, beryllium, etc.
• AlSi, AlSiCu, aluminum sintered materials include: AICuMg, with - AI Cu 3.8-4.4, Mg 0.5 -1, 0: AlMgSi with AI Si 0.4-0.8 Mg 0.5-1.0, AIZnMgCu 0.05 0.6 Cu 0.25-1.6 Mg 0.1-1.5 Zn 1.5 8.0, AlSi with more than about 7% Si, an
• the invention relates to light metal sintered parts made of light-metal alloys that are difficult to machine. Hypereutectic alloys can also be produced, further advantages being obvious to the person skilled in the art on the basis of his specialist knowledge.
• the advantages of the sintered parts produced according to the invention include the following: finest and uniform grain sizes of wear carriers, significantly finer wear carrier distribution, no segregation and segregation, completely homogeneous structure and extremely high dimensional accuracy - the distortions that occur during hot sintering do not occur in the process according to the invention and become so manufactured very dimensionally stable parts.
• the former powder particles can no longer be seen in the microscope using the method according to the invention, while the very fine grain structure of the structure also exhibits an elongated deformation, which also mechanically improves the strength of the sintered composite produced in this way.
• the sintered parts according to the invention are characterized by an at least 150% higher elongation than those of the same material composition, which are produced by powder forging, sintering or casting.
• wear carriers are typical. A finest and uniform grain size of the wear carriers and a significantly finer distribution of the same compared to other processes can be achieved. There are no segregations and segregations and it is preserved as a homogeneous structure. It is an extremely simple process for the production of highly wear-resistant sintered metal components with extremely high dimensional accuracy. Hypereutectic alloys can also be produced.
• fibers such as ceramic fibers, carbon fibers or hard material fibers: higher strengths - increase in tensile strength, increase in yield strength, increase in elastic modulus, better heat resistance and creep resistance - a reduction in the coefficient of thermal expansion is obtained.
• wear carriers or hard materials typical SiC particles, AIN, BN, TiB2, boron carbide, SiO2, WC: fibers such as carbon fibers, metal fibers, ceramic or glass fibers.
• Suitable metal phases can be selected from aluminum, titanium, copper, beryllium, magnesium, calcium, nickel, lithium, chromium, molybdenum, tungsten, bronzes, niobium, lead, zinc and cobalt.
• the process can also be used to sinter a composite (preferably powder compact) consisting of several areas of different composition - that is to say a sintered part with layers, rings, strips, etc.
• a composite preferably powder compact
• This can be interesting, for example, if a hard layer is required as the outer material - for example for cutting discs or the like - but a cheaper, more ductile and elastic material is desired as the inner material.
• the method according to the invention enables production in one step by means of continuous isostatic pressing, which means that several materials are then sintered together.
• Sintered parts with a hard cutting edge can also be produced from a different material composition than other areas.
• 1 shows a schematic representation of the process steps in comparison with conventional sinter pressing of aluminum-silicon alloy
• 2 shows a microscopic image of solid-state sections made of the AISi14% alloy - produced by melt-metallurgical casting, using the method according to the invention and using conventional sintering.
• Fig. 4 Friction coefficient curves of AISi14% against 100 Cr6 - by the method according to the invention and parts produced by sintering
• Fig. 5 Sintered products with inhomogeneous sections - shown schematically.
• Fig. 6 Schematic process flow of the production of sintered products with inhomogeneous sections
• a preferred embodiment of the invention is described below on the basis of the production of AISi14% moldings which have hitherto usually been hot-sintered - but this is by no means restricted to this application - other sinterable metallic powder, such as Ti, Ta, Mg , Be, Cs, Cu can be processed.
• Fig. 1 the process flow according to the teaching of the invention is shown schematically.
• the method comprises the production of a continuously sintered part, which is produced by continuously isostatically pressing a sinterable material mixture without lubricant from a sintered mold closed by a die.
• the starting material here a non-homogeneously melting mixture of aluminum powder with 13% by weight silicon powder (AlSi melts only in the range 5-7% homogeneous) is mixed intimately and then in a powder press for the production of Powder bolts not transferred to near-net shape. There it is pressed cold into a bolt-like green body under high pressure. The bolt-like green body is transferred to a system for continuous isostatic sintering - here an extrusion press - and pressed through the die under sintering.
• the AISM4 sintered part emerges from the die at temperatures up to 70% of the melting point of the main component as a sintered continuous profile, the outer contour of which is close to the final shape.
• the continuously sintered profile is then mechanically separated according to the desired disc height and the material discs at 250 ° C for 30 minutes. heat treated.
• the sintered disks originating from the heat treatment are then calibrated in a calibration press at a force of 150 KN - ie the final shape, which is very closely tolerated in terms of dimensions, is achieved.
• the sintered parts produced in this way no longer have to be decapsulated and have a flow behavior which is sufficient for calibration. They can then be used as finished parts without further post-processing.
• AlSi 14% sintered parts were conventionally produced by sintering, by pressing a green compact with aluminum oxide with 14% by weight silicon Si with a pressing aid Hoechst Wachs C into a disk, then treating the disk in a heat treatment step at 410 ° C. for 20 minutes , subsequently sintered in a sintering furnace for 30 min at 590 ° C and subsequently heat-treated again at 240 ° C for 240 min, produced as comparison products.
• FIG. 2 shows a comparison of the microstructures of the sintered aluminum disks made of AISM4, produced with conventional hot sintering according to the comparative test and produced according to the isostatic pressing according to the invention. It is clearly shown that the part produced according to the invention has a smaller grain size and fewer segregated areas - the sintered part produced according to the invention is therefore more homogeneous in its properties.
• FIG. 3 shows the coefficient of friction curves of hot isostatically pressed AISi14% shaped bodies and continuously isostatically pressure-sintered AISi14% shaped bodies according to the invention against 100Cr6. It can clearly be seen that the isostatic pressure-sintered material initially has a greater surface roughness, but this is rolled out quickly, so that the coefficient of friction in the later course of the friction test for the isostatically pressure-sintered material is lower than for the hot isostatically pressed product. This suggests a higher ductility of the isostatically pressure-sintered material.
• the sintered bodies produced by the process according to the invention have less scattering — can therefore be set more precisely and therefore also deliver fewer missing parts.
• the sintered parts are more homogeneous and also stretchable, which improves the elastic behavior, as is required in particular of mechanically stressed parts, such as chain wheels against steel chains, rotor and stator in a camshaft adjuster system or oil pump parts, bearing parts, pump wheels etc.
• FIG. 5 shows the result of the production of sintered parts according to the invention with different material areas - here in FIG. 5a a cut round sintered part with a different outer layer - in FIG. 5b a two-layer angular sintered part; 5c shows a tubular sintered part with different layers; 5d shows a strip-shaped distribution in sintered parts.
• a connection of different sintered materials is thus possible simultaneously with the production of the sintered part - for example, the application of an outer layer reinforced with hard materials can be avoided by direct "Mitansintem" as a separate process step - etc.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Powder Metallurgy (AREA)
• Adornments (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)

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• 2001
  • 2001-07-20 DE DE10135485A patent/DE10135485A1/de not_active Withdrawn
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  • 2001-11-23 DE DE50103474T patent/DE50103474D1/de not_active Revoked
  • 2001-11-23 ES ES01127413T patent/ES2227044T3/es not_active Expired - Lifetime
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• 2002
  • 2002-07-22 BR BR0211267-1A patent/BR0211267A/pt not_active Application Discontinuation
  • 2002-07-22 DE DE10293319T patent/DE10293319D2/de not_active Expired - Fee Related
  • 2002-07-22 CA CA002438397A patent/CA2438397A1/en not_active Abandoned
  • 2002-07-22 WO PCT/DE2002/002692 patent/WO2003011501A2/de not_active Application Discontinuation
  • 2002-07-22 US US10/483,645 patent/US20040208772A1/en not_active Abandoned
  • 2002-07-22 JP JP2003516724A patent/JP2004536232A/ja active Pending
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  • 2002-07-22 DE DE50201420T patent/DE50201420D1/de not_active Revoked
  • 2002-07-22 EP EP20020754408 patent/EP1412113B1/de not_active Revoked
  • 2002-07-22 AT AT02754408T patent/ATE280647T1/de not_active IP Right Cessation
  • 2002-07-22 ES ES02754408T patent/ES2231721T3/es not_active Expired - Lifetime
  • 2002-07-22 HU HU0401206A patent/HUP0401206A2/hu unknown

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