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Iron powder composition

a technology of iron powder and composition, applied in the field of iron powder composition, can solve the problems of increasing the wear of the die, unable to use zinc stearate or ethylene bisstearamide, and the tendency of lubricant to stick to the die wall, so as to reduce or eliminate the current problems

Inactive Publication Date: 2003-02-13
HOGANAS AB
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008] An object of the present invention is to reduce or eliminate current problems associated with large scale production.
[0035] 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.

Problems solved by technology

The extremely elevated temperatures of hot-pressing, however, introduce processing problems and accelerate wear of the dies.
In practice, however, it has proved impossible to use zinc stearate or ethylene bisstearamide (commercially available as ACRAWAX.RTM..), 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.
It has however been found that this lubricant has a tendency of sticking to the die wall, which requires frequent cleaning of the die.
Another disadvantage is that the obtained green bodies are stained.
Our experience of this product is that it is difficult to obtain a constant composition and quality, which in turn may result in components of varying quality.
This is may cause problems when the lubricant is used in large scale industrial production.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 2

[0046] 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 U.S. Pat. No. 5,154,881.

[0047] As can be seen the lubricant according to the present invention is superior as regards the ejection force, the ejection energy and the springback.

3 TABLE 3 Ejection Ejection Spring- GD Force Energy back (g / cm.sup.3) (N / mm.sup.2) (J / cm.sup.2) (%) Lubricant 7.46 9.7 20.9 0.121 according to the present invention Lubricant 7.40 15.4 21.9 0.201 according to U.S. Pat. No. 5 154 881

[0048] Compaction pressure 700 MPa

[0049] Temperature powder / Die 130.degree. C. / 150.degree. C.

[0050] The iron-based powder was Distaloy AE available from Hogans AB, Sweden.

[0051] 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 was added in an amount of 0...

example 3

[0052] 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.

[0053] The iron-based powder was Distaloy AE available from Hogans AB, Sweden.

[0054] 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 was added in an amount of 0.06% by weight.

[0055] The powder was heated to a temperature of 130.degree. C. and the temperature of die was 150.degree. C. The compaction pressure was 700 MPa.

4 Molecular Weight of Lubricant GD (g / cm.sup.3) 2000 7,44 3000 7,41 4000 7,31

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Abstract

A powder composition for warm compaction comprising an iron-based powder and 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)nCO-; 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

[0001] The present invention relates to metal powder compositions. Particularly the invention relates to iron-based compositions suitable for compaction at elevated temperatures.[0002] 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).[0003] Distinct advantages arise by pressing at temperatures above ambient temperature. The tensile strength and work hardening rate of most metals is reduced with increasing temperatures, and improved density and strength can be attained at lower compaction pressures. The extremely elevated temperatures of hot-pressing, however, introduce proces...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B22F1/10C10M105/68B22F3/02C10M171/06
CPCB22F1/0059B22F2003/023B22F2003/145C10M105/68C10M171/06B22F1/10B22F1/103B22F3/10
Inventor VIDARSSON, HILMARKNUTSSON, PER
Owner HOGANAS AB