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
  • B22F3/02—Compacting only
• • 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
  • B22F3/12—Both compacting and sintering
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/12—Metallic powder containing non-metallic particles
• • 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
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
• • 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
  • B22F3/02—Compacting only
  • B22F2003/026—Mold wall lubrication or article surface lubrication
• • 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
  • B22F3/12—Both compacting and sintering
  • B22F3/16—Both compacting and sintering in successive or repeated steps
  • B22F3/164—Partial deformation or calibration
  • B22F2003/166—Surface calibration, blasting, burnishing, sizing, coining
• • 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
  • B22F3/24—After-treatment of workpieces or articles
  • B22F2003/241—Chemical after-treatment on the surface
  • B22F2003/242—Coating
• • 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
  • B22F3/24—After-treatment of workpieces or articles
  • B22F2003/248—Thermal after-treatment
• • 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 present invention relates to sintered components and method for producing sintered components from a sinterable material.
• the usual sintering process comprises the steps of filling a sinterable material/composition into a press mold, pressing it to a so-called green compact, and sintering this green compact at sintering temperatures, followed if necessary by a homogenizing annealing, and also a subsequent sizing and possibly a hardening.
• the step of sizing is time-consuming and costly, since the component taken from the sintering step proper often does not have sufficient dimensional stability.
• a sizing is correspondingly indispensable.
• Sizing thus represents a step in sinter processing, which because of its many-layered nature is not only determinative for the quality of the final sintered component to be delivered, but also is negative from the economic viewpoint.
• the present invention relates to sintered components and methods for preparing sintered components, which include the steps of introducing a sinterable material into a first mold, pressing the sinterable material to form a green compact; at least partially post-compressing the green compact in a second press mold, and, sintering the green compact.
• the density of the post-compressed green compact is greater than the density prior to compression.
• the sinterable materials includes conventionally known sinterable materials, such as for example, iron-containing powders, aluminum-containing powders, ceramic-containing powders, metal-containing powders, or combinations thereof.
• the present invention relates to sintered components and methods for preparing sintered components, which include the steps of introducing a sinterable material into a first mold, pressing the sinterable material to form a green compact; at least partially post-compressing the green compact in a second press mold, and, sintering the green compact.
• the density of the post-compressed green compact is greater than the density prior to compression.
• Methods for producing sintered components and composite parts from a sinterable material include steps wherein, the sinterable material, comprising 0.6-1.8 wt. % of a binder or lubricant, with respect to the total amount of the powder mixture, is filled into a first press mold; in a second step, the sinterable material is pressed to a green compact; in a third step, the green compact is at least partially post-compressed in a second press mold by uniaxial compression; in a fourth step, the post-compressed green compact is sintered, a density being attained in the post-compression performed in the third step which is about 2 to 40%, preferably 5-30%, more preferably 15-25%, above that obtained before post-compression.
• the advantageous result is attained that the oxide layers present on the surface of the material used are mechanically broken, so that a better cold welding between the individual material particles is attained in the pressing process. Furthermore by this means the diffusion of the individual material particles during the sintering process proper is also improved. Components with increased strength values and in particular higher hardness can hereby be attained.
• sintered components are to be understood to be components which are produced completely from a sinterable material; on the other hand, there are hereby understood also composite parts, where the base member of such a composite part can for example be produced from an aluminum-containing powder mixture and the member further connected to the base member from a further material, for example iron or cast steel, sintered or solid, or of solid cast aluminum.
• the composite part can for example have a sintered layer of an aluminum-containing powder mixture only on the end face or its surface, whereas the base member is for example of steel or cast iron, sintered or solid.
• the sintered components can be sized and/or heat hardened.
• the sinterable material is applied to the base member, for example by conventional methods; it can also be provided, for example, to spray on the material in powder form (wet powder spraying, WPS). It is necessary to prepare a suspension of the sinterable material for this purpose.
• the suspension necessary for this purpose preferably includes solvents, binders, stabilizers and/or dispersing agents.
• Particularly preferred solvents are chosen from a group comprising water, methanol, ethanol, isopropanol, terpenes, C 2 -C 5 alkenes, toluene, trichloroethylene, diethyl ether and/or C 1 -C 6 aldehydes and/or ketones.
• Preferred solvents are those evaporable at temperatures below 100° C.
• the amount of the solvent used lies in a range of about 40 through 70 wt. % with respect to the sinterable powder mixture used, preferably in a range of about 50-65 wt. %.
• the post-compression (which may also be termed intermediate compression) taking place in the third step can be performed by means of the usual and known method for pressing a green compact.
• the green compact pressed in the second step can be again introduced into a conventional mold and at least partially post-compressed in this by corresponding press plunger.
• the post-compression tools can be completely or partially of conical design, so that particularly high compressions can be attained at given predetermined places of the green compact.
• the green compact is dewaxed in a further step before the third step.
• the dewaxing preferably takes place under nitrogen, hydrogen, air and/or mixtures of the said gases, particularly also with a specific supply of air. Furthermore this dewaxing can take place with endogenous and/or exogenous gas, however also in vacuum.
• the dewaxing can preferably be performed by means of applied microwaves and/or ultrasound, or else with only microwaves to control the temperature. Finally, the dewaxing can also be performed with solvents such as alcohol and the like, or by supercritical carbon dioxide with or without the effect of temperature, microwaves or ultrasound or combinations of the said methods.
• a mold in which the possibly dewaxed green compact is introduced is sprayed with a lubricant before introduction of the green compact.
• the dewaxed green compact can also be soaked in lubricant.
• the sintering process it is particularly advantageous for the sintering process to be performed under nitrogen with a dew point below ⁇ 40° C., preferably below ⁇ 50° C.
• the sintering preferably takes place under pure nitrogen.
• the sintering can also be performed under air, mixtures of nitrogen and hydrogen with or without specific air supply, endogenous gas or exogenous gas, or in vacuum; sintering can take place by superposed microwaves or else with microwaves for temperature control.
• an additional surface compression in general an introduction of internal pressure stresses in the surface region, is possible by sandblasting or shot peening.
• a sizing may be performed before or after the homogenizing annealing. The sizing is performed at room temperature or an elevated temperature, up to the forging temperature, also with the use of pressures up to 900 N/mm 2 . If necessary, sizing can be performed even above the solidus line, it then being possible also to remove the component directly from the sintering heat.
• the sizing and/or forging tools used for sizing can be wholly or partially of conical shape, whereby particularly high compressions can be attained at given regions of the component.
• the temperature of the sizing and/or forging tools can differ according to the component to be processed, and can possibly be kept in the isothermal range.
• a surface compression or application of internal pressures to the component is also possible before or after sizing.
• coatings may be applied to the sintered component.
• Processes are here preferred with which the components are hard coated and/or anodized, for example, thermal spray processes such as plasma spraying, flame spraying, or else physical and/or chemical processes such as PVD, CVD and the like.
• coatings may also be applied in purely chemical ways such as for example by lubricant lacquers which may contain Teflon, or nanocomposite materials, can be applied.
• the surface of the composites can be modified by a coating according to the hardness, roughness and coefficient of friction in a predetermined manner according to the use purpose.
• the sinterable material is a powder and/or powder mixture containing iron and/or aluminum, more preferably aluminum-containing powder mixtures.
• powder-form materials high densities of the as yet uncompressed green compacts can already be obtained before the actual sintering step.
• a sinterable powder mixture comprising 60-98.5%, with respect to the total amount of the powder mixture, preferably 85-98.5 wt. %, of an Al-based powder of metals and/or their alloys, comprising Al, 0.2-30 wt. % Mg, 0.2-40 wt. % Si, 0.2-15 wt. % Cu, 0.2-15 wt. % Zn, 0.2-15 wt. % Ti, 0.2-10 wt. % Sn, 0.2-5 wt. % Mn, 0.2-10 wt. % Ni and/or less than 1 wt.
• % of As, Sb, Co, Be, Pb and/or B the weight percent fractions being respectively based on the total amount of Al-based powder; and 0.8-40 wt. %, based on the total amount of the powder mixture, preferably 1.5-20 wt. %, of a metallic powder, chosen from a first group of metals and/or their alloys, consisting of Mo, W, Cr, V, Zr and/or Yt.
• the sinterable powder mixture furthermore advantageously includes a second group of metals and/or their alloys, consisting of Cu, Sn, Zn, Li and/or Mg.
• a second group of metals and/or their alloys consisting of Cu, Sn, Zn, Li and/or Mg.
• the second group of metals and/or their alloys transform into an at least partially liquid state at the sintering temperature, whereby the binding of the first group of metals in particular and of their alloys, and/or their alloying to the aluminum-based powder, is improved.
• the ratio of the amount of the first group of metals and/or their alloys to that of the second group in the powder mixture is preferably in a range of 1:8 to 15:1 parts by weight.
• the ratio preferably lies in a range of 2:1 to 6:1 parts by weight.
• the Al-based powder has, besides Al, 0.2-15 wt. % Mg, 0.2-16 wt. % Si, 0.2-10 wt. % Cu, and/or 0.2-15 wt. % Zn, respectively with respect to the total amount of Al-based powder.
• the second group of metals and/of their alloys preferably has Cu, Zn and/or Sn.
• the sinterable powder mixture includes lubricant in an amount of 0.2-5 wt. % based on the total amount of the powder mixture.
• lubricants there can be provided on the one hand self-lubricating means such as, for example, MoS 2 , WS 2 , BN, MnS as well as graphite and/or other carbon modifications such as coke, polarized graphite, and the like.
• 1-3 wt. % of lubricant is added to the sinterable powder mixture.
• the sinterable powder mixture can furthermore comprise binders and/or lubricants. These are preferably chosen from a group comprising polyvinyl acetate, waxes, in particular amide waxes such as ethylene-bisstearoylamide, shellac, polyalkylene oxides and/or polyglycols. Polyalkylene oxides and/or polyalkylene glycols are preferably used as polymers and/or copolymers with average molecular weights in a range of 100-500,000 g/mol, preferably 1,000-3,500 g/mol, more preferably 3,000-6,500 g/mol.
• the media are preferably used in an amount in a range of 0.01-12 wt., preferably in a range of 0.5-5 wt. %, more preferably in a range of 0.6-1.8 wt. %, respectively with respect to the total amount of the powder mixture.
• the binder and/or lubricant also facilitate the removal from the press mold of the components made from the sinterable powder mixture.
• the powder mixture can be produced by mixing the individual components in conventional devices such as tumble mixers, both when hot (hot mixing) and also at room temperature (cold mixing); hot mixing is preferred.
• Sintered components produced by the disclosed methods have strength values and hardnesses which clearly exceed those alloys which are produced by conventional methods.
• the sintered components according to the invention preferably have a tensile strength of at least 140 N/mm 2 , measured according to DIN EN 10002-1. More preferably the tensile strength is more than 200 N/mm 2 , yet more preferably more than 300 N/mm2.
• the components sintered according to the invention have an elasticity modulus of at least 70 kN/mm 2 , measured according to DIN EN 10002-1, and more preferably is greater than 80 kN/mm 2 .
• the sintered components have a hardness (HB 2.5 mm/62.5 kg) of at least 100, measured according to DIN EN 24498-1.
• the hardness is more preferably greater than 110, and yet more preferably greater than 125.
• the sintered component is formed as a gearwheel, pump wheel, particularly oil pump wheel, and/or rotor set.
• An Al-based powder of the composition Al 4 CulMg 0.5 Si (corresponds to the designation AC2014 of a conventional aluminum alloy, the basic powder having 4 wt. % Cu, 1 wt. % Mg, 0.5 wt. % Si and 94.5 wt. % Al, with respect to the total amount of powder) of the Company ECKA Granulate GmbH & Co. KG, Velden, Germany, with the company designation ECKA Alumix 123 (92.5% Al), and 1.5 wt. % of an amide wax as binder, of the Hoechst Company with designation Mikrowachs C, were mixed with molybdenum or tungsten powder according to the following Table 1. Mixing took place in a tumble mixer by addition of the molybdenum or tungsten powder to the already present Al-based powder at room temperature during 5 minutes.
• the Al-based powder had a grain size distribution between 45 and 200 ⁇ m, the average particle diameter D 50 being 75-95 ⁇ m.
• the admixed molybdenum or tungsten powder was from the Company H.C. Starck Gmbh & Co. KG, Goslar, Germany and had an average particle diameter D 50 of 25 ⁇ m with a grain size distribution in a range of 5-50 ⁇ m.
• the powder mixture was then placed in a die mold and pressed under a pressure of about 175 N/mm 2 (calculated for a wheel end surface of 20 cm 2 ) for about 0.2-0.5 sec. at room temperature to a green compact in the form of a pump wheel.
• the density of the green compact was about 2.35-2.38 g/cm 3 .
• the thus produced green compact was then dewaxed for about 30 min at about 430° C., and was then sintered at a sintering temperature of 610° C. under a pure nitrogen atmosphere with a dew point of ⁇ 50° C. in a belt furnace set to a speed of 3.4 m/h for 30 min.
• the green compacts were on Al 2 O 3 plates.
• a homogenizing annealing was then performed for 1.5 hours at a temperature of 515° C.
• the sintered pump wheel was then shock cooled by quenching with water with a temperature of about 40° C. for 10 sec.
• a sizing was then performed to a theoretical density of 97-98% using a pressure of about 810 N/mm 2 at 200° C.
• the above trial under numeral 1 was repeated, a copper powder however being admixed, sold by the Company Eckhart Granules under the trademark ECKA KUPFER CH-S.
• the admixture took place such that the molybdenum powder or the tungsten powder was first mixed with the copper powder in a tumble mixer at room temperature for 5 min and this was then mixed with the Al-based powder in a tumble mixer.
• the copper powder had an average particle diameter D 50 of 25 ⁇ m and a grain size distribution in a range of about 5 to about 50 ⁇ m.
• the copper powder was produced electrolytically; the individual particles had a dendritic form.
• sintered components particularly based on an Al-based powder, which not only have excellent strength values, but also in particular have high hardness.
• Such articles can hereby advantageously be used at strongly stressed places, particularly in the motor or else in gears.
• sintered components can be more favorably and quickly produced by the possible omission of sizing and of hardening by hot storage.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Powder Metallurgy (AREA)
• Compositions Of Oxide Ceramics (AREA)
• Press-Shaping Or Shaping Using Conveyers (AREA)

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• 2002
  • 2002-01-29 DE DE10203283A patent/DE10203283C5/de not_active Expired - Fee Related
• 2003
  • 2003-01-21 EP EP03734681A patent/EP1469963B1/de not_active Revoked
  • 2003-01-21 MX MXPA04005695A patent/MXPA04005695A/es active IP Right Grant
  • 2003-01-21 WO PCT/EP2003/000529 patent/WO2003064083A2/de not_active Application Discontinuation
  • 2003-01-21 ES ES03734681T patent/ES2244938T3/es not_active Expired - Lifetime
  • 2003-01-21 BR BR0307194-4A patent/BR0307194A/pt not_active Application Discontinuation
  • 2003-01-21 CN CNB038028182A patent/CN1290649C/zh not_active Expired - Fee Related
  • 2003-01-21 AT AT03734681T patent/ATE299770T1/de not_active IP Right Cessation
  • 2003-01-21 AU AU2003239254A patent/AU2003239254A1/en not_active Abandoned
  • 2003-01-21 JP JP2003563755A patent/JP2005526178A/ja active Pending
  • 2003-01-21 DE DE50300811T patent/DE50300811D1/de not_active Revoked
  • 2003-01-21 KR KR10-2004-7011254A patent/KR20040070318A/ko not_active Application Discontinuation
• 2004
  • 2004-07-29 US US10/909,202 patent/US20050036899A1/en not_active Abandoned

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