Patent ID: 9581056
Date: 2017-02-28
CPC Classifications: B22F,C22C,F01L

Claim:
1. A valve seat having a surface for contacting with a valve, the valve seat comprising: an iron-based sintered alloy having an interior and providing said surface for contacting with a valve; an oxide formed by oxidation treatment and mainly composed of triiron tetroxide, the oxide being on said surface and in said interior of the iron-based sintered alloy; and hard particles having a hardness of 600 to 1600 HV and being formed from at least one compound of carbides, silicides, nitrides, borides, and intermetallic compounds containing one or more elements selected from groups 4a to 6a of the periodic table, wherein in a cross section of said interior of the iron-based sintered alloy, an average area ratio of the oxide in the cross section is 5 to 20%, and an average area ratio of the hard particles in the cross section is 5 to 45%.