Patent ID: 7122064

Claim:
A process for making alumina-zirconia abrasive grain product comprising: forming a melt from a mixture of source materials containing aluminum oxide, zirconium oxide, titanium oxide and silicon oxide in the presence of excess carbon as a reducing agent wherein the amount of silicon oxide is from 2.0 to 5.7 wt-% relative to all of the source materials; and quenching the melt to produce the abrasive grain product comprising: (a) aluminum oxide; (b) zirconium oxide with at least 85 wt.-% thereof being in tetragonal crystal form; (c) titanium compounds in reduced form of oxide, suboxides, carbides, oxycarbides, oxycarbonitrides, silicides or mixtures thereof present from 2–5 wt.-%; (d) silicon compounds content, expressed as silicon oxide, between 0.2 and 0.7 wt.-%; (e) overall carbon content between 0.03 and 0.5 wt.-%, (f) impurities content derived from source materials being less than 3 wt.-% and rare earths content, expressed as oxides, of less than 0.1 wt.-%, and (g) the abrasive grain having an extremely fine structure with dentritic eutectic domains of aluminum oxide and zirconium oxide with a median cross section of less than 15 microns.