Sintered valve seat and production method therefor

摘要

A sintered valve seat includes: a matrix; 5 to 40 mass % of a hard phase dispersed in the matrix, the hard phase containing 48 to 60 mass % of Mo; 3 to 12 mass % of Cr; 1 to 5 mass % of Si; and the balance of Co and inevitable impurities; and a structure in which a Cr sulfide is dispersed around the hard phase. The hard phase is formed with a Co base alloy matrix and compounds which are mainly composed of Mo silicides and are integrally precipitated in the Co base alloy matrix.