Specialized metallurgical processes – compositions for use therei – Compositions – Loose particulate mixture containing metal particles
Reexamination Certificate
1999-10-25
2001-11-06
Jenkins, Daniel J. (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Compositions
Loose particulate mixture containing metal particles
C419S023000, C419S011000, C075S255000, C075S246000
Reexamination Certificate
active
06312497
ABSTRACT:
TECHNICAL FIELD
BACKGROUND AND SUMMARY
In the manufacture of diamond tools by hot sintering, with or without pressure applied, of an intimate mixture of diamonds and of a binder material, use is made for the binder phase, that is the material forming the matrix of the tool after the sintering operation, either of fine cobalt powders (from less than 1 to about 6 &mgr;m in diameter as measured with the Fisher Sub Sieve Sizer, called hereafter Fisher SSS) or of mixtures of fine powders, such as mixtures of fine cobalt, nickel and iron powders, or of coarse pre-alloyed powders, such as steel powders obtained by atomization of a melt.
The use of fine cobalt powder gives very good results from a technical standpoint; its major drawback stems from the high price fluctuations of the cobalt powder.
Using mixtures of fine powders, matrices are obtained whose strength, hardness and wear resistance are relatively low. The use of coarse pre-alloyed powders (from 10 to 50 &mgr;m) requires high sintering temperatures, in the order of 1000 to 1300° C., at which temperatures severe degradation of the diamonds takes place, resulting in weakened diamond crystals and poor retention of the diamonds in the matrix.
In SU-A-1689053 an iron-based metallic binder for diamond tools with improved tool performance, and containing Ni, Cu and C and Sn, is described. No specifications are given concerning the preparation of the binder and the characteristics of the powders involved.
The object of the present invention is to provide fine pre-alloyed powders, containing copper and iron as two of the alloying elements, and with less or no dependence on cobalt, whose use as a binder in the manufacture of diamond tools by hot sintering avoids the aforementioned drawbacks.
DETAILED DESCRIPTION
For this purpose, the new pre-alloyed powder used according to the invention has an average particle size of less than 10 &mgr;m, as measured with the Fisher SSS, and a loss of mass by reduction in hydrogen of less than 2%, as measured according to the standard ISO 4491-2:1989. The powder contains, in % by weight, up to 40% of cobalt, up to 50% of nickel, from 5 to 80% of iron and from 5 to 80%, of copper, the other components in the powder consisting of unavoidable impurities. It has been found that such a powder may be sintered at moderate temperatures, i.e. from 600 to 1000° C., giving a high hardness and a good resilience, which may be adapted to the particular requirements of the users of diamond tools, by varying the composition of the powder.
It is necessary for the particle size to be less than 10 &mgr;m as measured with the Fisher SSS, in order that the powder be sinterable at moderate temperatures; advantageously it is less than 5 &mgr;m.
The loss of mass by reduction in hydrogen of less than 2% corresponds to a sufficiently low oxygen content; higher oxygen contents would allow the diamonds to degrade during the sintering operation.
The abovementioned cobalt, nickel, iron and copper contents are necessary to obtain a sintered matrix with a suitable hardness and resilience, i e. in the order of the hardness and resilience offered by sintered fine cobalt powder. Particularly, it has been found that the incorporation of copper into the pre-alloyed powder results in a less brittle matrix than when copper is omitted. Preference is given to a cobalt content of up to 30%, a nickel content of up to 30%, an iron content of at least 10%, and a copper content of at least 10%.
The powder of the invention may be prepared by heating, in a reducing atmosphere, a hydroxide, oxide, carbonate, basic carbonate (a mixture of hydroxide and carbonate), an organic salt, or a mixture of two or more of these compounds, of the constituents of the alloy (“constituents of the alloy” denotes all the metallic elements present in the alloy).
The hydroxide, carbonate, basic carbonate and organic salt may be prepared by adding an aqueous solution of the constituents of the alloy to an aqueous solution of, respectively, a base, a carbonate, a base and a carbonate, and a carboxylic acid, separating the precipitate thus obtained from the aqueous phase and drying the precipitate.
The aqueous solution of the constituents of the alloy may be a chloride solution, a sulfate solution, a nitrate solution or a mixed solution of these salts.
REFERENCES:
patent: 2238351 (1941-04-01), Van Der Pyl
patent: 2410512 (1946-11-01), Lindquist et al.
patent: 4049380 (1977-09-01), Yih et al.
patent: 4231762 (1980-11-01), Hara
patent: 53-37992 (1978-04-01), None
patent: 1689053 (1991-11-01), None
Engström et al., “Powders and processes for high performance PM steels”,Powder Metallurgy, vol. 35, No. 1, 1992, pp. 67-72.
Tsuchiya et al., “Copper-Iron Alloy Binder in Diamond Tools for Cutting and Polishing of Fine Ceramics”, Chemical Abstracts, vol. 108, No. 22, May 30, 1988, Columbus, Ohio, US, Abstract No. 191222, see abstract & JP 62 287 035 A (Fuji DIE Co., Ltd., Japan).
Antonelli Terry Stout & Kraus LLP
Jenkins Daniel J.
N. V. Union Miniere S.A.
LandOfFree
Pre-alloyed, copper containing powder, and its use in the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pre-alloyed, copper containing powder, and its use in the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pre-alloyed, copper containing powder, and its use in the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2617031