Abrasive tool making process – material – or composition – With inorganic material – Metal or metal oxide
Patent
1981-06-09
1982-12-07
Czaja, Donald E.
Abrasive tool making process, material, or composition
With inorganic material
Metal or metal oxide
51293, B24D 302
Patent
active
043625355
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a sintered metal bonded diamond composition particularly favorable as abrasives in the form of pellet or wheel for use in fining or polishing lenses or other various materials.
BACKGROUND ART
As sintered metal bonded abrasive articles for the purposes as mentioned above, those of copper-tin basis have so far been used extensively. They exhibit, however, low grinding ratios, in other words, short life, and poor rates of stock removal.
As regards another type of sintered metal bonded abrasive articles, i.e., sintered metal bonded diamond abrasive articles of nickel basis, while a sintering temperature of 1000.degree. C. or more, at which rapid graphitizing of diamond begins to occur, is necessary for preparation thereof because of the high melting point of nickel, lower temperature sintering of nickel has become possible by the use of more finely devided nickel powders, thereby developing a sintered abrasive article having an excellent fining function as well as an improved holding force of diamond grits (Japanese Patent Application Laid-open No. 83190/1978). Furthermore, in order to prevent the clogging of nickel base abrasive articles during long runs of fining, a sintered metal bonded diamond abrasive article exhibiting improved grinding ratios as well as increased rates of stock removal has been developed by the technique wherein an element capable of forming an intermetallic compound with nickel is added to a nickel base to precipitate and disperse a hard and brittle phase of the intermetallic compound in the base (Japanese Patent Application Laid-open No. 7517/1980).
However, the latter sintered metal bonded abrasive article of nickel basis gives stock removal rates fluctuating to a great extent with variations, due to prior roughing process, in surface roughness of works to be ground, and this constitutes a serious obstacle to its practical use in certain applications.
DISCLOSURE OF INVENTION
The object of the invention is to eliminate such disadvantages as mentioned above of sintered metal bonded diamond abrasive articles of nickel basis.
The invention provides an improved sintered metal bonded diamond abrasive article of nickel basis by replacing part of nickel by copper, a relatively inexpensive metal, and adding tin and phosphorous at the same time.
In the abrasive article of the invention, the metal bond holding diamond grits contains 2 to 30% by weight of copper, 1 to 40% by weight of tin, and 0.2 to 3% by weight of phosphorous, with the proviso that the total content of copper, tin, and phosphorous is less than 50% by weight and the remainder is nickel.
The point of the invention is that the choice of suitable compounding proportions of copper, tin, and phosphorous to the base nickel gives excellent grinding characteristics that could not be anticipated from the known behavior of two elements, tin and phosphorous, in the respective nickel-tin and nickel-phosphorous binary systems.
BEST MODE FOR CARRYING OUT THE INVENTION
The base metal nickel in this invention, which as the main constituent of the matrix retains diamond grits, is used, in consideration of diamond-holding force, to be present in an amount of at least 50% by weight in the matrix. The nickel, the main constituent of the matrix, can be replaced by cobalt in certain cases, and thereby nearly the same results are obtained as in the case with nickel.
The copper forms a solid solution with the nickel and promotes the tin-nickel and phosphorous-nickel intermetallic compounds to precipitate. When the copper content is less than 2% by weight of the matrix, the variation in rate of stock removal is severe, and on the contrary, when the copper content exceeds 30% by weight, the rates of stock removal and life are poor.
The elements, tin and phosphorous, react with the solid solution of copper in nickel to form fine phase of the respective intermetallic compounds, promote uniform and moderate wear of bond and increase the hardness of bond. Powder of each element is added in such an a
REFERENCES:
patent: 3036907 (1962-05-01), Bibbins
patent: 3293012 (1966-12-01), Smiley
patent: 3372010 (1968-03-01), Parsons
patent: 3389981 (1968-06-01), Strauss
Emura Akira
Hayakawa Izumi
Isobe Eiji
Czaja Donald E.
Mitsui Mining & Smelting Co. Ltd.
Thompson W.
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