High fracture toughness electro-discharge machineable ceramic whisker reinforced ceramic composites and tooling made therefrom

Abstract

An electro-conductive ceramic comprising a non-electroconductive matrix ceramic, an electro-conductive ceramic in relatively large proportion to permit efficient electro-discharge machining (EDM) of the ceramic and ceramic whiskers of low aspect ratio and short length dispersed in the ceramic body to provide high fracture toughness, stength and hardness despite the relatively large proportion of electro-conductive ceramic. Complex geometries and features such as holes, chamfers, slots, angles, changing radii an complex curves can be electro-discharge machined into the ceramic body after hot processing or hot-isostatic pressing to achieve maximum density and mechanical properties. A particularly advantageous high temperature extrusion die, powder metal compacting die hardware and cutting tools formed of Al.sub.2 O.sub.3, TiC and SiC whiskers have been produced and tested. Test results show that the detrimental surface damage caused by the electro-discharge machining process can be overcome with larger proportions of relatively small single crystal ceamic whiskers of low aspect ratio and short length thoroughly dispersed in the matrix.

Dependencies are inferred from the claim text.