VALVE SEAT FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a valve seat which exhibits enhanced duribity and also permits improvement in the durability of a valve face. SOLUTION: The valve seat is composed of a sintered alloy prepared by sintering an iron-base alloy and fine hard particles. The fine hard particles are added to the iron-base ally in such a way that the product of the Vickers hardness and area ratio of the particles becomes 200-250. The product (250 HVA) of the Vickers hardness and area ratio of the fine hard particles at the point (intersection) at which respective characteristics of wear rate of the valve seat and the valve face coincide practically with each other is used as a reference, and the range from the reference point to the product (200 HVA) of the Vickers hardness and area ratio of the fine hard particles is determined as tolerance, and, e.g. 14 wt.% Fe-Mo alloy particles and 9 wt.% Co-Mo-Cr alloy particles are added as the fine hard particles respectively.