Kabushiki Kaisha Riken

Kimiaki Hashimoto

Hiroji Henmi

To provide a sintered valve seat having excellent valve coolability making it usable for high-efficiency engines, as well as excellent deformation resistance, wear resistance and detachment resistance, the valve seat is provided with a two-layer structure having a seat layer repeatedly abutting a valve face, and a support layer abutting bottom and inner peripheral surfaces of a valve-seat-press-fitting opening of a cylinder head; the seat layer containing at least one selected from Co-based hard particles and Fe-based hard particles in a matrix of Cu or its alloy; and the support layer containing at least one selected from Fe particles and Fe alloy particles in a matrix of Cu or its alloy.

Sintered valve seat

To provide a press-fitting, sintered valve seat having excellent valve coolability enabling use in high-efficiency engines, as well as excellent deformation resistance and wear resistance, first and second hard particles differing in hardness are dispersed in a total amount of 25-70% by mass in a network-shaped Cu matrix, the second hard particles having hardness of 300-650 HV0.1, lower than that of the first hard particles, and 0.08-2.2% by mass of P is contained in the sintered valve seat.

To provide a press-fit, sintered valve seat having high valve coolability and wear resistance for use in a high-efficiency engine, and its production method, Cu powder having an average particle size of 45 &#x3bc;m or less and purity of 99.5% or more is used to form a network-connected Cu matrix, even though a relatively large amount of hard Co-based alloy particles are added; and Fe&#x2014;P alloy powder is used for densification by liquid-phase sintering.

Sintered valve seat and its production method

An iron-based sintered alloy valve seat having excellent wear resistance and machinability, which can be used for high-power diesel engines, an intermetallic compound having Vickers hardness Hv of 800-1200 is used, and C and P in the composition of the iron-based sintered valve seat are by mass 1.2-1.6% and 0.80-1.35%, respectively.

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Kumagaya, Japan

Kimiaki Hashimoto