Patent ID: 7855159

Claim:
A SiAlON ceramic armor made from a starting powder mixture, the ceramic armor comprising: a ceramic body comprising between about 60 weight percent and about 98 weight percent alpha SiAlON phase that contains an alpha SiAlON-bound rare earth element and between about 2 weight percent and about 40 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 0.2 and about 1.0; the ceramic body further comprising sintering aid residue present as a result of the starting powder mixture containing between about 4 weight percent and about 14 weight percent of an oxide of an alpha SiAlON-bound rare earth element, and between about 0.5 weight percent and about 5 weight percent of an oxide of an unbound rare earth element, and the alpha SiAlON-bound rare earth element being different from the unbound 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 17.5 GPa.