Patent ID: 7829491

Claim:
A silicon nitride sintered body comprising β-sialon expressed by a composition formula of Si 6−z Al z O z N 8−z , wherein z value being the dissolved amount is 0.1 to 1, as a main phase, a grain boundary phase and Fe silicide particles, wherein the grain boundary phase contains RE (Group III elements in the periodic table)-Al—Si—O, and component ratios of AI, Si and RE in terms of Al 2 O 3 , SiO 2 , RE 2 O 3 , respectively is 5 to 50 mass % of Al 2 O 3 , 5 to 20 mass % of SiO 2 , and the balanced amount of RE 2 O 3 , the grain boundary phase is contained in a range of 20 volume % or less to 100 volume % of the sintered body, and the Fe silicide particles is contained in 0.02 to 3 mass % in terms of Fe to 100 mass % of the sintered body.