Composite ceramic cutting tool

Claim 1

An abrasion resistant composite cutting tool consisting essentially of a particulate material selected from the group consisting of the refractory metal carbides, nitrides, carbonitrides and mixtures thereof of titanium, tungsten, hafnium, niobium, tantalum, vanadium, and combinations thereof uniformly distributed in a matrix comprising a modified silicon aluminum oxynitride, said particulate material comprising from about 5 volume percent to about 60 volume percent of said cutting tool and having an average particle size of between about 0.5 microns and about 20 microns; said modified silicon aluminum oxynitride having a modifier selected from the group consisting of the oxides of silicon, yttrium, magnesium, hafnium, zirconium, beryllium, the lanthanides and combinations thereof, said modified silicon aluminum oxynitride being formed from about 2 to about 25 volume percent of said modifier, from about 20 to about 90 volume percent silicon nitride, and from about 5 to about 60 volume percent aluminum oxide.