WO2002083345A1 - Iron powder composition including an amide type lubricant and a method to prepare it - Google Patents

Iron powder composition including an amide type lubricant and a method to prepare it Download PDF

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Publication number
WO2002083345A1
WO2002083345A1 PCT/SE2002/000762 SE0200762W WO02083345A1 WO 2002083345 A1 WO2002083345 A1 WO 2002083345A1 SE 0200762 W SE0200762 W SE 0200762W WO 02083345 A1 WO02083345 A1 WO 02083345A1
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WO
WIPO (PCT)
Prior art keywords
powder
lubricant
powder composition
atoms
composition according
Prior art date
Application number
PCT/SE2002/000762
Other languages
French (fr)
Inventor
Hilmar Vidarsson
Per Knutsson
Original Assignee
Höganäs Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Höganäs Ab filed Critical Höganäs Ab
Priority to EP02723031A priority Critical patent/EP1390171B1/en
Priority to KR1020037013547A priority patent/KR100838925B1/en
Priority to DE60201903T priority patent/DE60201903T2/en
Priority to CA002443481A priority patent/CA2443481C/en
Priority to AT02723031T priority patent/ATE281899T1/en
Priority to BRPI0208914-9A priority patent/BR0208914B1/en
Priority to MXPA03009487A priority patent/MXPA03009487A/en
Priority to JP2002581132A priority patent/JP3908167B2/en
Priority to AU2002253770A priority patent/AU2002253770B2/en
Priority to US10/201,974 priority patent/US6755885B2/en
Publication of WO2002083345A1 publication Critical patent/WO2002083345A1/en

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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
    • 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
    • B22F1/103—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing an organic binding agent comprising a mixture of, or obtained by reaction of, two or more components other than a solvent or a lubricating agent
    • 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
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • 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
    • 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
    • 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
    • B22F3/14—Both compacting and sintering simultaneously
    • B22F2003/145—Both compacting and sintering simultaneously by warm compacting, below debindering temperature

Definitions

  • Iron powder composition including an amide typ lubricant and a method to prepare it.
  • the present invention relates to metal powder compositions. Particularly the invention relates to iron- based compositions suitable for compaction at elevated 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 lubricant according to the US patent 5,744,433 contains an oligomer of amide type, which has a weight - average molecular weight M w of 30,000 at the most. Very high densities and green strengths may be obtained by warm compacting powder compositions when the lubricant has a molecular weight above 4000, the preferred lubricant molecule having a molecular weight of about 6500. It has however been found that this lubricant has a tendency of sticking to the die wall, which requires fre- quent cleaning of the die. Another disadvantage is that the obtained green bodies are stained.
  • the amide lubricant consists of the reaction product of a monocarboxylic acid, a dicarboxylic acid and a diamine .
  • the only lubricant tested according to this patent is ADVAWAX® 450, the composition of which is not described in detail but the reaction product obtained includes i.a. ethylene bisstearamide according to Chemis-CIVS.
  • Our experience of this product is that it is difficult to obtain a constant com- position and quality, which in turn may result in components of varying quality. This may cause problems when the lubricant is used in large scale industrial production.
  • An object of the present invention is to reduce or eliminate current problems associated with large scale production.
  • a second object is to provide a new type of lubricant useful in metal compositions intended for compaction at elevated temperatures.
  • a third object is to provide a metal powder for pro- ducing components without stains.
  • a fourth object is to provide a metal composition including lubricant, which during the compaction of the metal powder does not deposit on the die wall.
  • a powder composition comprising an iron-based powder and new oligomer amide type lubricant.
  • the composition may also include one or more additives, such as binders, flow agents, processing aids and hard phases.
  • the warm compaction may be performed by mixing an iron-based powder with the oligomer amide type lubricant and optionally a binder, preheating the powder composition and compacting the metal -powder composition in a pre-heated tool.
  • 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 CO- B is amino or carbonyl
  • A is alkylen having 4-16 C atoms optionally including up to 4 O atoms ma is an integer 1-10 mb is an integer 1-10 n is an integer 5-11.
  • 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 O atoms, and ma and mb which may be the same or different, is an integer 2-5.
  • Examples of preferred lubricants to be used in the iron based compositions according to the present invention are:
  • EBS is formed when the lubricant according to the present invention is prepared.
  • EBS has the chemical formula
  • CH 3 (CH 2 ) 16 CO-HN(CH 2 ) 2 NH-OC(CH 2 ) 16 CH 3 ) is a molecule without lactam units which is in contrast to the lubricants according to the present invention.
  • the preferred lubricants have a molecular weight between 1000 and 5000, most pref- erably between 1500 and 3000.
  • the lubricant molecule may be prepared according standard procedures for amide oligomer as described in e.g. "Principles of Polymerization” third edition by George Odian (John Wiley & Sons, Inc.) .
  • the lubricant preferably consists of at least 80% of the amide having the formula described above.
  • up to 20% by weight of other types of lubricants may be added, as long as the advantageous properties of the new lubricant is not detrimentally affected.
  • This 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 advantageous feature of the invention, since it enables high densities to be achieved.
  • iron-based powder encompasses powder es- sentially made up of pure iron; iron powder that has been pre-alloyed 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 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 compressibility.
  • 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 new powder composition may contain one or more additives such as binders, flow agents, processing aids and hard phases .
  • the binder may be added to the powder composition in accordance with the method described in U.S. Pat. No.
  • 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 diox- ides, such as the Aerosil 200 and R812 products, from Degussa Corporation.
  • the processing aids used in the metal -powder composition may consist of talc, forsterite, manganese sulphide, 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 iron-based powder was Distaloy AE available from H ⁇ ganas AB, Sweden. This powder was mixed with 0.3% by weight of ultrafine graphite and 0.6% by weight of a lubricant according to the present invention. A flow enhancing agent Aerosil® 200 was added in an amount of 0.06% by weight.
  • the new oligomer amide type lubricant according to the present invention is superior not only as regards the ejection force, the ejection energy, the springback but also when it comes to the appearance of the compacted component. Additionally the lubricant does not deposit on the die wall .
  • the lubricant according to the present invention is superior as regards the ejection force, the ejection energy and the springback.
  • the iron-based powder was Distaloy AE available from H ⁇ ganas AB, Sweden.
  • This powder was mixed with 0.3% by weight of ultra- fine graphite and 0.6% by weight of a lubricant according to the present invention.
  • a flow enhancing agent Aerosil was added in an amount of 0.06% by weight.
  • EXAMPLE 3 discloses a comparison of densities of green bodies obtained with the oligomer amide lubricants which are used according to the present invention and which have different molecular weights.
  • the iron-based powder was Distaloy AE available from H ⁇ ganas AB, Sweden.
  • This powder was mixed with 0.3% by weight of ultra- fine graphite and 0.6% by weight of a lubricant according to the present invention.
  • a flow enhancing agent Aerosil was added in an amount of 0.06% by weight.
  • the powder was heated to a temperature of 130 °C and the temperature of die was 150 °C.
  • the compaction pressure was 700 MPa.
  • the molecular weight of the oligomer amide lubricant is lower than (about) 2000 the properties of the powder composition becomes worse with regards to flow, and the lubricant will have a tendency of sticking to the die wall and the surface of the ejected compact.
  • the sticky nature of such surfaces increases the risk of formation of rough surfaces on the final part owing to powder which may be collected onto the ejected compact.

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

Abstract

A powder composition for warm compaction comprising an iron-based powdered a lubricant powder consisting essentially of an amide described by the following formula D-Cm-B-A-B-Cm-D wherein 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 CO-;B is amino or carbonyl; A is alkylene having 4-16 C atoms optionally including up to 4 O atoms m is an integer 1-10 and n is an integer 5-11.

Description

Iron powder composition including an amide typ lubricant and a method to prepare it.
FIELD OF THE INVENTION
The present invention relates to metal powder compositions. Particularly the invention relates to iron- based compositions suitable for compaction at elevated temperatures .
BACKGROUND OF THE INVENTION
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) .
Distinct advantages arise by pressing at temperatures above ambient temperature. The tensile strength and work hardening rate of most metals is reduced with in- creasing temperatures, and improved density and strength can be attained at lower compaction pressures. The extremely elevated temperatures of hot-pressing, however, introduce processing problems and accelerate wear of the dies. Therefore, current efforts are being directed to- wards the development of metal compositions suitable for warm-pressing processes.
The US patent 4,955,789 (Musella) describes warm compaction in general. According to this patent, lubricants generally used for cold compaction, e.g. zinc ste- arate, can be used for warm compaction as well. In prac- tice, however, it has proved impossible to use zinc ste- arate or ethylene bissteara ide (commercially available as ACRA AX®.), which at present are the lubricants most frequently used for cold compaction, for warm compaction. The problems, which arise, are due to difficulties in filling the die in a satisfactory manner.
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 lubricant according to the US patent 5,744,433 contains an oligomer of amide type, which has a weight - average molecular weight Mw of 30,000 at the most. Very high densities and green strengths may be obtained by warm compacting powder compositions when the lubricant has a molecular weight above 4000, the preferred lubricant molecule having a molecular weight of about 6500. It has however been found that this lubricant has a tendency of sticking to the die wall, which requires fre- quent cleaning of the die. Another disadvantage is that the obtained green bodies are stained.
In the US. Patent 5,154,881 the amide lubricant consists of the reaction product of a monocarboxylic acid, a dicarboxylic acid and a diamine . The only lubricant tested according to this patent is ADVAWAX® 450, the composition of which is not described in detail but the reaction product obtained includes i.a. ethylene bisstearamide according to Chemis-CIVS. Our experience of this product is that it is difficult to obtain a constant com- position and quality, which in turn may result in components of varying quality. This may cause problems when the lubricant is used in large scale industrial production. OBJECTS OF THE INVENTION
An object of the present invention is to reduce or eliminate current problems associated with large scale production.
A second object is to provide a new type of lubricant useful in metal compositions intended for compaction at elevated temperatures.
A third object is to provide a metal powder for pro- ducing components without stains.
A fourth object is to provide a metal composition including lubricant, which during the compaction of the metal powder does not deposit on the die wall.
SUMMARY OF THE INVENTION
These objects are achieved by using a powder composition comprising an iron-based powder and new oligomer amide type lubricant. The composition may also include one or more additives, such as binders, flow agents, processing aids and hard phases.
The warm compaction may be performed by mixing an iron-based powder with the oligomer amide type lubricant and optionally a binder, preheating the powder composition and compacting the metal -powder composition in a pre-heated tool.
DETAILED DESCRIPTION OF THE INVENTION The new amide type lubricant used according to the present invention may be represented by the following formula
D-Cma-B-A-B-Cnb-D wherein
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)nCO- B is amino or carbonyl
A is alkylen having 4-16 C atoms optionally including up to 4 O atoms ma is an integer 1-10 mb is an integer 1-10 n is an integer 5-11.
It is preferred that D is COR, wherein R is an aliphatic group 16 - 20 C atoms, C is -NH (CH)nCO- wherein n is 5 or 11; B is amino; A is alkylen having 6-14 C atoms optionally including up to 3 O atoms, and ma and mb which may be the same or different, is an integer 2-5.
Examples of preferred lubricants to be used in the iron based compositions according to the present invention are:
CH3 (CH2) 16CO-[HN(CH2) nCO]2 -HN (CH2 ) 12NH-[OC (CH2) n H]2-
Figure imgf000005_0001
CH3 (CH2) ι6CO-[HN(CH2) nC0]2 -HN (CH2 ) 12NH-[OC (CH2) nNH]3 -
Figure imgf000005_0002
CH3 (CH2) 16CO-[HN(CH2) nC0]3 -HN (CH2 ) 12NH-[OC (CH2) ιχNH]3- OC(CH2)16CH3
CH3 (CH2) 16CO-[HN(CH2) nC0]3 -HN (CH2 ) 12NH-[OC (CH2) nNH]4- OC(CH2)ι6CH3
CH3 (CH2) 16CO-[HN(CH2) nCO]4 -HN (CH2 ) ι2NH-[OC (CH2) nNH]4- OC(CH2)i6CH3 CH3 (CH2) 16CO-[HN(CH2) 11CO]4-HN(CH2) i2NH-[OC (CH2 ) nNH]5-
Figure imgf000006_0001
CH3 (CH2) i6CO-[HN(CH2) 11CO]5-HN(CH2) ι2NH-[OC (CH2) nNH]5- OC(CH2)ι6CH3
Other examples are
CH3)CO-HN(CH2)5CO-HN(CH2)2NH-OC(CH2)5NH-OC(CH3) having the
MW 370.49;
CH3 (CH2) 20CO-HN (CH2) nCO-HN (CH2) 12NH-OC (CH2) lxNH-OC (CH2) 20CH3 having the MW 1240.10 CH3 (CH2) 20CO- [HN (CH2) nCO] 10-HN (CH2) 12NH- [OC (CH2) nNH] 10-
OC(CH2)20CH3 having the MW 8738.04
CH3 (CH2) 4CO- [HN (CH2) nCO] 3-HN (CH2) ι2NH- [OC (CH2) X1NH] 3-
OC(CH2)4CH3 having the MW 1580.53 CH3 (CH2) 4CO- [HN (CH2) 5CO] 7-HN (CH2) 6NH- [OC (CH2) 5NH] 7-OC (CH2) 4CH3 having the MW 1980.86
CH3 (CH2) 20CO- [HN (CH2) 5CO] 7-HN (CH2) 6NH- [OC (CH2) 5NH] 7-
OC(CH2)20CH3 having the MW 2429.69 and
CH3 (CH2) i6 H- [OC (CH2) nNH] 4-CO (CH2) 10CO- [HN (CH2) nCO] 4-
HN(CH2)16CH3 having the MW 2283.73
The chemical differences between the new lubricant and the lubricant described in the US patent 5,744,433 are that the new molecule has a central diamine or diacid moiety and identical terminal groups on both ends. The chemical difference between the new lubricant and the lu- bricant described in the US patent 5,154,881 is that the new lubricant molecule includes the unit -NH (CH) n CO- . In contrast to the lubricant known from US 5 154 881 no
EBS is formed when the lubricant according to the present invention is prepared. EBS has the chemical formula
CH3(CH2) 16CO-HN(CH2)2NH-OC(CH2)16CH3) is a molecule without lactam units which is in contrast to the lubricants according to the present invention.
As regards the molecular weight of the new lubricant molecule it has been found that the preferred lubricants have a molecular weight between 1000 and 5000, most pref- erably between 1500 and 3000.
The lubricant molecule may be prepared according standard procedures for amide oligomer as described in e.g. "Principles of Polymerization" third edition by George Odian (John Wiley & Sons, Inc.) . According to the present invention the lubricant preferably consists of at least 80% of the amide having the formula described above. Thus up to 20% by weight of other types of lubricants may be added, as long as the advantageous properties of the new lubricant is not detrimentally affected. This 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 advantageous feature of the invention, since it enables high densities to be achieved. As used in the description and the appended claims, the expression "iron-based powder" encompasses powder es- sentially made up of pure iron; iron powder that has been pre-alloyed 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) . Examples of alloying elements are 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 (Fe3P and FeMo) . Unexpectedly good results are obtained when the lubricants according to the invention are used in combination with iron-based powders having high compressibility. Generally, 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. Apart from the iron-based powder and the lubricant, the new powder composition may contain one or more additives such as binders, flow agents, processing aids and hard phases .
The binder may be added to the powder composition in accordance with the method described in U.S. Pat. No.
5,368,630 (which is hereby incorporated by reference) and may be organic compounds such as cellulose ester resins, hydroxyalkyl cellulose resins having 1-4 carbon atoms in the alkyl group, or thermoplastic phenolic resins. A type of flow agent, which can be used according to the present invention, is disclosed in the US patent 5,782,954 (which is hereby incorporated by reference). 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 diox- ides, such as the Aerosil 200 and R812 products, from Degussa Corporation.
The processing aids used in the metal -powder composition may consist of talc, forsterite, manganese sulphide, 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, Al2 03, and various ceramic materials.
The invention is further illustrated by the following examples, which are to be interpreted only as exam- pies but should not limit the scope of protection.
EXAMPLE 1
The following tables disclose a comparison of properties between components prepared from powder mixtures including the lubricant according to the present invention and the amide type lubricant disclosed in the US patent 5,744, 433. Table 1
Figure imgf000010_0001
Table 2
Figure imgf000011_0001
Temperature Powder/Die: 120°C/120°C
* lubricant preferred according to US patent 5,744, 433
The iron-based powder was Distaloy AE available from Hόganas AB, Sweden. This powder was mixed with 0.3% by weight of ultrafine graphite and 0.6% by weight of a lubricant according to the present invention. A flow enhancing agent Aerosil® 200 was added in an amount of 0.06% by weight.
As can be seen the new oligomer amide type lubricant according to the present invention is superior not only as regards the ejection force, the ejection energy, the springback but also when it comes to the appearance of the compacted component. Additionally the lubricant does not deposit on the die wall . EXAMPLE 2
The following table discloses a comparison of properties between components prepared from powder mixtures including the lubricant according to the present invention and the amide type lubricant disclosed in the US patent 5,154,881.
As can be seen the lubricant according to the present invention is superior as regards the ejection force, the ejection energy and the springback.
Table 3
Figure imgf000012_0001
Compaction pressure 700 MPa Temperature powder/Die 130°C/150°C
The iron-based powder was Distaloy AE available from Hόganas AB, Sweden.
This powder was mixed with 0.3% by weight of ultra- fine graphite and 0.6% by weight of a lubricant according to the present invention. A flow enhancing agent Aerosil was added in an amount of 0.06% by weight.
EXAMPLE 3 The following example discloses a comparison of densities of green bodies obtained with the oligomer amide lubricants which are used according to the present invention and which have different molecular weights.
The iron-based powder was Distaloy AE available from Hόganas AB, Sweden.
This powder was mixed with 0.3% by weight of ultra- fine graphite and 0.6% by weight of a lubricant according to the present invention. A flow enhancing agent Aerosil was added in an amount of 0.06% by weight. The powder was heated to a temperature of 130 °C and the temperature of die was 150 °C. The compaction pressure was 700 MPa.
Molecular Weight of Lubricant GD (g/cm3)
2000 7,44
3000 7,41
4000 7,31
If the molecular weight of the oligomer amide lubricant is lower than (about) 2000 the properties of the powder composition becomes worse with regards to flow, and the lubricant will have a tendency of sticking to the die wall and the surface of the ejected compact. The sticky nature of such surfaces increases the risk of formation of rough surfaces on the final part owing to powder which may be collected onto the ejected compact.

Claims

1. A powder composition for warm compaction comprising an iron-based powder and a lubricant powder, said lubricant consisting essentially of an amide represented by the following formula
D-Ona-B-A-B-Cmb-D
wherein
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)nCO- B is amino or carbonyl
A is alkylen having 4-16 C atoms optionally including up to 4 O atoms ma is an integer 1-10 mb is an integer 1-10 n is an integer 5-11.
2. A powder composition according to claim 1 wherein D is COR, wherein R is an aliphatic group 16 - 20 C atoms, C is -NH (CH)nCO- 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, respectively is an integer 2-5, whereby ma and mb may be the same or different.
3. A powder composition according to any one of the claims 1-2 wherein the lubricant consists of a compound selected from the group consisting of
CH3 (CH2) 16C0-[HN(CH2) nCO]2 -HN (CH2 ) 12NH-[0C (CH2 ) nNH]2* OC(CH2)16CH3 CH3 (CH2) 16CO-[HN(CH2) nCO]2 -HN (CH2 ) 12NH-[OC (CH2 ) nNH]3-
OC(CH2)16CH3
CH3 (CH2) 16CO-[HN(CH2) nCO]3 -HN (CH2 ) 12NH-[OC (CH2 ) nNH]3-
OCCH2)16CH3 CH3 (CH2) 16CO-[HN(CH2) ιχC0]3 -HN (CH2 ) 12NH-[OC (CH2 ) 1:LNH]4- OC(CH2)16CH3
CH3 (CH2) 16CO-[HN(CH2) nC0]4 -HN (CH2 ) 12NH-[OC (CH2 ) 11NH]4-
Figure imgf000015_0001
CH3 (CH2) ι6CO-[HN(CH2) ιχC0]4-HN (CH2 ) 12NH-[OC (CH2 ) n H]5- OC(CH2)i6CH3
CH3 (CH2) 16CO-[HN(CH2) nCO]5-HN(CH2) 12NH-[OC (CH2 ) nNH]5- OC(CH2)16CH3
4. A powder composition according to any one of the claims 1-3, wherein said amide has a molecular weight of
1500 to 3000 and is present in said composition in an amount of less than 1% by weight.
5. A powder composition according to any one of the claims 1-4, wherein the lubricant powder is provided in a concentration 0.2 to 0.8% by weight of the composition.
6. A powder composition according to any one of the claims 1-5, which additionally contains one or more additives selected from the group consisting of binders, processing aids, and hard phases.
7. A powder composition according to any one of the claims 1-6, wherein said iron-based powder is compressible, and at least 80% by weight of said lubricant powder is made up of said amide oligomer.
8. A powder composition according to any one of the claims 1-6, wherein said composition is essentially free from ethylenebisstearamide .
9. A powder composition according to any one of the claims 1-8, c h a r a c t e r i s e d in that said iron- based powder has a carbon content of at most 0.04% by weight .
10. A method for producing sintered products comprising :
(a) mixing an iron-based powder with a lubricant powder as defined in the previous claims;
(b) preheating the metal -powder composition,
(c) compacting the metal -powder composition in a preheated tool, and optionally
(d) sintering the compacted metal -powder composition at a temperature above 1050° C to form a sintered product.
PCT/SE2002/000762 2001-04-17 2002-04-17 Iron powder composition including an amide type lubricant and a method to prepare it WO2002083345A1 (en)

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EP02723031A EP1390171B1 (en) 2001-04-17 2002-04-17 Iron powder composition including an amide type lubricant and a method to prepare it
KR1020037013547A KR100838925B1 (en) 2001-04-17 2002-04-17 Iron powder composition including an amide type lubricant and a method to prepare it
DE60201903T DE60201903T2 (en) 2001-04-17 2002-04-17 IRON POWDER COMPOSITION USING AN AMID LUBRICANT AND PROCESS FOR MAKING IT
CA002443481A CA2443481C (en) 2001-04-17 2002-04-17 Iron powder composition including an amide type lubricant and a method to prepare it
AT02723031T ATE281899T1 (en) 2001-04-17 2002-04-17 IRON POWDER COMPOSITION WITH AN AMIDE LUBRICANT AND METHOD FOR PRODUCING IT
BRPI0208914-9A BR0208914B1 (en) 2001-04-17 2002-04-17 iron powder composition including an amide lubricant.
MXPA03009487A MXPA03009487A (en) 2001-04-17 2002-04-17 Iron powder composition including an amide type lubricant and a method to prepare it.
JP2002581132A JP3908167B2 (en) 2001-04-17 2002-04-17 Iron powder composition containing amide type lubricant and method for preparing the same
AU2002253770A AU2002253770B2 (en) 2001-04-17 2002-04-17 Iron powder composition including an amide type lubricant and a method to prepare it
US10/201,974 US6755885B2 (en) 2001-04-17 2002-07-25 Iron powder composition

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US7169208B2 (en) * 2004-06-10 2007-01-30 Inco Limited Method and composition for dispersing extra-fine nickel powder
US7314498B2 (en) * 2004-10-19 2008-01-01 Pmg Ohio Corp. Sintered alloys for cam lobes and other high wear articles
US7722803B2 (en) * 2006-07-27 2010-05-25 Pmg Indiana Corp. High carbon surface densified sintered steel products and method of production therefor
JP5841089B2 (en) * 2013-03-13 2016-01-13 株式会社豊田中央研究所 Molding powder, lubricant concentrated powder, and method for producing metal member
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WO2003106077A1 (en) * 2002-06-14 2003-12-24 Höganäs Ab Composition and process for warm compaction of stainless steel powders
US6712873B2 (en) 2002-06-14 2004-03-30 Höganäs Ab Warm compaction of steel powders
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WO2006122633A1 (en) * 2005-05-20 2006-11-23 Ems-Chemie Ag Polyamide oligomers and their use
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US7910652B2 (en) 2005-05-20 2011-03-22 Ems-Chemie Ag Polyamide molding materials with an improved flowability, the production thereof and its use
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