Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
  • C10M105/56—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing nitrogen
  • C10M105/68—Amides; Imides
• • 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
  • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
• • 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
  • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
  • B22F1/108—Mixtures obtained by warm mixing
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
  • C10M171/06—Particles of special shape or size
• • 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
  • B22F2003/023—Lubricant mixed with the metal 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
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

• the present invention relates to metal powder compositions and a method of preparing such compositions.
• the invention relates to iron-based composi- tions having consistent apparent density and flowability at different temperatures.
• the powder metallurgy art generally uses different standard temperature regimes for the compaction of a metal powder to form a metal component . These include chill-pressing (pressing below ambient temperatures) , cold-pressing (pressing at ambient temperatures) , hot- pressing (pressing at temperatures above those at which the metal powder is capable of retaining work-hardening) , and warm-pressing (pressing at temperatures between cold- pressing and hot-pressing) .
• the US patents 5,744, 433 (Storstrom et al) and 5,154,881 (Rutz) disclose metal powder compositions including amide lubricants which are especially developed for warm compaction.
• the US patent 5,744, 433 discloses a lubricant for metallurgical powder compositions contains an oligomer of amide type, which has a weight-average molecular weight M w of 30,000 at the most.
• the amide lubricant consists of the re- action product of a monocarboxylic acid, a dicarboxylic acid and a diamine.
• ADVAWAX.®. 450 which is an ethylenebisstearamide product .
• An object of the present invention is to reduce or eliminate current problems associated with large scale production. Another object is to provide a new type of lubricant useful in metal compositions intended for compaction at elevated temperatures . Still another problem is to provide an iron-based powder composition distinguished by excellent flow rate and apparent density.
• a further object is to provide a powder composition, which generates a minimum of dust and the preparation of which does not require the use of organic solvents.
• Another object is to provide a method for warm compaction such a metal powder composition.
• a powder composition comprising an iron-based powder, at least one oligomer amide type lubricant, at least one fatty acid and optionally one or more additives such as flow agents, process- ing aids and hard phases.
• the method according to the invention includes the steps of
• iron-based powder encompasses powder essentially made up of pure iron; iron powder that has been prealloyed with other substances improving the strength, the hardening properties, the electromagnetic properties or other desirable properties of the end products; and particles of iron mixed with particles of such alloying elements (diffusion annealed mixture or purely mechanical mixture).
• alloying elements are nickel, copper, molybdenum, chromium, manganese, phosphorus, carbon in the form of graphite, and tungsten, which are used either separately or in combination, e.g. in the form of compounds (Fe 3 P and FeMo) .
• the lubricants according to the invention are used in combination with iron-based powders having high compressability.
• such powders have a low carbon content, preferably below 0.04% by weight.
• Such powders include e.g. Distaloy AE, Astaloy Mo and ASC 100.29, all of which are commercially available from Hoganas AB, Sweden.
• the lubricant used according to the present invention is new and may be represented by the following formula :
• D is -H, COR, CNHR, wherein R is a straight or branched aliphatic or aromatic group including 2-21 C atoms C is the group -NH (CH) n C0-
• A is alkylen having 4-16 C atoms optionally including up to 4 0 atoms ma is an integer 1-10 mb is an integer 1-10 n is an integer 5-11.
• the lubricant has the chemical structure wherein D is COR, wherein R is an aliphatic group 16 - 20 C atoms, C is -NH (CH) n CO- wherein n is 5 or 11; B is amino; A is alkylen having 6-14 C atoms optionally including up to 3 0 atoms, and ma and mb, which may be the same or different is an integer 2-5.
• Examples of such lubricants may be selected from the group consisting of
• the oligomer amide type lubricant which is added to the iron-based powder is preferably in the form of a solid powder, can make up 0.1-1% by weight of the metal- powder composition, preferably 0.2-0.8% by weight, based on the total amount of the metal -powder composition.
• the possibility of using the lubricant according to the present invention in low amounts is an especially advanta- geous feature of the invention, since it enables high densities to be achieved
• the fatty acid used according to the present inventions is preferably a fatty acid having 10-22 C atoms.
• examples of such acids are oleic acid, stearic acid and palmitic acid.
• the amount of the fatty acid is normally 0.005-0.15, preferably 0.010-0.08 and most preferably 0.015-0.07 % calculated on the total weight of the powder composition. Fatty acid contents below 0.005 make it difficult to achieve an even distribution of the fatty acid. If the content is higher than 0.15 there is a considerable risk that the flow will deteriorate.
• the melting point of the fatty acid should be lower than that of the amide oligomer lubricant.
• the new powder composition may contain one or more addi- tives selected from the group consisting of processing aids and hard phases .
• the processing aids used in the metal -powder composition may consist of talc, forsterite, manganese sul- phide, sulphur, molybdenum disulphide, boron nitride, tellurium, selenium, barium difluoride and calcium di- fluoride, which are used either separately or in combination.
• the hard phases used in the metal -powder composition may consist of carbides of tungsten, vanadium, titanium, niobium, chromium, molybdenum, tantalum and zirconium, nitrides of aluminium, titanium, vanadium, molybdenum and chromium, Al 2 0 3 , and various ceramic materials.
• the flow agent which is preferably a silicon dioxide, is used in an amount from about 0.005 to about 2 percent by weight, preferably from about 0.01 to about 1 percent by weight, and more preferably from about 0.025 to about 0.5 percent by weight, based on the total weight of the metallurgical composition. Furthermore, the flow agent should have an average particle size below about 40 nanometers.
• Preferred silicon oxides are the silicon dioxide materials, both hydrophilic and hydrophobic forms, commercially available as the Aerosil line of silicon dioxides, such as the Aerosil 200 and R812 products, from Degussa Corporation.
• the iron-based powder, at least one oligomer amide type lubricant, at least one fatty acid and optionally one or more additives, such as processing aids and hard phases, are heated to a temperature above the melting point of the lubricant; the obtained mixture is subsequently cooled to a temperature below the melting point of the lubricant and above the melting point of the fatty acid ; and a pulverulent flow agent is added to the obtained mixture, which is then mixed and cooled.
• FIG. 1 shows the effect of the combination of the oligomer amide type lubricant defined above and a fatty acid (stearic acid) on the apparent density.
• FIG. 2 shows the effect of the combination of the lubricant defined above and a fatty acid (stearic acid) on the flow rate.
• the powder mixture tested was prepared by dry mixing Distaloy AE (an iron-based powder available from H ⁇ ganas AB, Sweden) with 0.6 % by weight of organic material which consisted of the oligomer amide type lubricant defined above and 0.03 or 0.05 % by weight of stearic acid. 0.3 % by weight of graphite was aslo added and the ob- tained mixture was heated to 165 °C. The mixture was cooled to 110 °C and 0.06 % by weight of Aerosil® was added at this temperature. Essentially the same results are obtained when the Aerosil is added at ambient temperature . The results disclosed in FIG.l and 2 respectively demonstrate that clear and unexpected effects on both apparent density and flow can be obtained with the powder compositions according to the present invention.
• the above mixture which included 0.03% by weight of stearic acid was also tested with regard to the dust reduction in comparison with a mixture prepared according to the US patent 5 368 630.
• the known mixture also included 0.6% by weight of organic material but in this case the organic material consisted of 0.55% by weight of lubricant and 0.15% by weight of an organic binder (cellulose butyrate) .
• the iron-based powder was Distaloy AE in both mixtures.
• the preparation of the known mixture involves dry mixing of the iron-based powder, the lubricant according to the US patent and 0.3% by weight of graphite.
• the organic binder was dissolved in acetone and added to the dry mixture and after thorough mixing. The acetone was removed and 0.06% by weight of Aerosil® was added to the dried mixture.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)
• Powder Metallurgy (AREA)

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Cited By (4)

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Citations (5)

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• 2001
  • 2001-04-17 SE SE0101343A patent/SE0101343D0/xx unknown
  • 2001-05-10 US US09/852,016 patent/US20020178863A1/en not_active Abandoned
  • 2001-05-16 TW TW090111713A patent/TWI235183B/zh not_active IP Right Cessation
• 2002
  • 2002-04-17 ES ES02724846T patent/ES2248547T3/es not_active Expired - Lifetime
  • 2002-04-17 CN CNB028084179A patent/CN1250684C/zh not_active Expired - Fee Related
  • 2002-04-17 DE DE60205610T patent/DE60205610T2/de not_active Expired - Fee Related
  • 2002-04-17 WO PCT/SE2002/000763 patent/WO2002083346A1/en active IP Right Grant
  • 2002-04-17 EP EP02724846A patent/EP1387730B1/en not_active Expired - Lifetime
  • 2002-04-17 JP JP2002581133A patent/JP4126230B2/ja not_active Expired - Fee Related
  • 2002-04-17 AT AT02724846T patent/ATE302081T1/de not_active IP Right Cessation

Patent Citations (5)

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