GB593908A - Improvement in metallic abrasive composition of matter - Google Patents

Abstract

In an abrasive composition in which abrasive particles, e.g., diamond fragments, are dispersed in a metal matrix, the matrix is formed of a mixture of powdered sintered metals comprising a fractional percentage of one or more of copper, silver, and gold, a small fractional percentage of indium, from 3 to 10 per cent. of manganese, nickel, or a mixture thereof, and the remainder of iron containing the eutectoid percentage of carbon. The copper, silver or gold increases corrosion resistance of the iron matrix, the indium prevents the accumulation of abrasive-removed particles in the interstices between the abrasive grains, and the manganese or nickel reduces the shrinkage of the product, thus reducing the moulding-pressure, and improves the strength and ductility. The copper, silver, or gold is used in an amount up to 1 per cent., but preferably a mixture of approximately .1 per cent. silver and .1 per cent. of gold is used. The indium is present up to about .1 per cent., while the manganese or nickel may be 5 per cent. The iron and carbon are preferably present in the form of carbonyl iron power, all of which should pass 400 mesh. The manganese should pass 200 mesh, and the copper, silver, or gold should pass 200-300 mesh. The metal powders are mixed in a ball mill, and the diamond fragments, between 100 and 120 mesh size, and preferably coated with a metal of the platinum group, such as rhodium, are mixed in. The mixture is pressed into a mould and then gradually heated in a non-oxidising atmosphere to about 750 DEG C, the mould being coated with a refractory material such as silica dust, graphite, alumina, or the like to facilitate removal of the product. After sintering, the mass is quenched. The ratio of diamond to metal may be 1 : 3. Specification 582,808 is referred to.