Abstract: Disclosed is a composite abrasive particle comprising a core abrasive crystal and a silicon carbide coating inherently bonded to substantially all of the exterior surfaces of said core crystal, said silicon carbide coating characterized by silicon carbide crystals having a random orientation substantially independent of the structure of the core crystal, the outer surface of the coating being conformationally irregular. Aggregates of the composite abrasive particles are interconnected by a matrix of silicon carbide which has an open structure. Preferred core abrasive crystals are diamond or cubic boron nitride.

Abstract: Disclosed is an improvement in a process for fabricating a polycrystalline diamond and/or cubic boron nitride-silicon carbide-silicon composite body fabricated by infiltrating silicon through a mixture of a carbonaceous material and non-diamond carbon coated diamond and/or cubic boron nitride under partial vacuum at elevated temperature. Such improvement comprises providing fibrous graphite for inclusion in the mixture, said fibrous graphite being subjected to heat treatment at a temperature of between about 800.degree. and 1700.degree. C. prior to its inclusion in the mixture and at a temperature of between about 800.degree. and 1550.degree. C. after its inclusion in the mixture. Such heat treatment is conducted under a total pressure of less than about 1 Torr. The vacuum silicon infiltration then is practiced on the mixture which includes the heat treated graphite fibers.

Abstract: An improved diamond aggregate abrasive is disclosed comprising milled saw diamond having an average size less than 75 microns held in a silver/copper alloy matrix which also contains a wetting agent for (e.g. titanium). Tests of grinding wheels containing this new aggregate have shown a marked improvement in grinding ratio over commercially available diamond aggregates.