Patent ID: 8318622

Claim:
A SiAlON armor ceramic made from a starting powder mixture including silicon nitride powder, the armor ceramic comprising: a ceramic body comprising between about 64 weight percent and about 90 weight percent alpha SiAlON phase that contains an alpha SiAlON-bound rare earth element wherein the alpha SiAlON-bound rare earth element is the sole rare earth element in the ceramic, and between about 5 weight percent and about 35 weight percent of a beta SiAlON phase of the formula Si 6−z Al z O z N 8−z wherein the value of “z” ranges between about 0.10 and about 0.35; the alpha SiAlON-bound rare earth element in the alpha SiAlON phase being present as a result of the starting powder mixture containing between about 1 weight percent and about 7 weight percent of an oxide of the alpha SiAlON-bound rare earth element; and the ceramic body having a fracture toughness (K IC ) greater than about 6.00 Mpa·m 1/2 and a Vickers hardness (H VN ) equal to greater than about 19.3 GPa.