Patent ID: 7629281

Claim:
A ceramic material of β-sialon (Si 6−z Al z O z N), polytype 12H, an intergranular amorphous or partly crystalline phase, and containing yttrium wherein: the amount of intergranular phase, measured as the area attributable to this phase in a SEM picture relative to the total area of the picture, is between about 5 and about 15%, the z-value is from about 0.7 to less than about 1.5 the amount of polytype 12H, measured as the ratio of the height in a Cu—Kα x-ray diffractogram of the 12H peak at a 2Θ value of 34° and the height in the same diffractogram of the β-sialon peak at a 2Θ value of 33° is between about 2 and about 20%, and, the yttrium content is from about 3.5 to about 5 wt-%.