Sintered alloy, method for production thereof and valve sheet

Abstract

To provide a sintered alloy capable of showing wear resistance and a process for producing the same as well as a valve seat of good wear resistance. A sintered alloy comprising 4-30% by weight Mo, 0.2-3% by weight C, 1-30% by weight Ni, 0.5-10% by weight Mn, 2-40% by weight Co, and the balance of inevitable impurities and Fe when the entirety is taken as 100% by weight. Aprocess for producing a sintered alloy in which a green compact of a raw mixture powder including hard particles is sintered, thereby producing said sintered alloy. A valve seat comprising said sintered alloy.

Description

[0001] The present invention relates to a sintered alloy of good wear resistance, a process for producing the same, and a valve seat comprising a sintered alloy of good wear resistance.[0002] Internal combustion engines applied to automotive engines and the like are provided with valves for inlet and outlet and valve seats on which the valves are seated.[0003] It is has been required for valve seats to exhibit high wear resistance. When valve seats are worn, there arises a problem that the valve seat recession occurs in which valve seats sink down upon being seated.[0004] To valve seats of good wear resistance, sintered alloys are applied in which Co-based hard particles are dispersed in Fe-based textures. And, Japanese Unexamined Patent Publication (KOKAI) No. 9-242,516 discloses a valve seat for internal combustion engines.[0005] The valve seat disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 9-242,516 is a valve seat for internal combustion engines in which cobalt-...

AI Technical Summary

Benefits of technology

[0010] The present invention has been done in view of such circumstances. Namely, it is an object to provide a sintered alloy capable of showing sufficient wear resistance and a process for producing the same as well as a valve seat of good wear resistance.

Problems solved by technology

When valve seats are worn, there arises a problem that the valve seat recession occurs in which valve seats sink down upon being seated.

However, the valve seat has a problem in that the wear resistance is insufficient when it is applied to gas engines as the valve seats.

On the other hand, in engines which use gaseous fuels such as liquefied petroleum gases (LPG: Liquefied Natural Gas) and compressed natural gases (CNG: Compressed Natural Gas), the lubricating property between the valves and valve seats has not been secured sufficiently because combustion products occur less.

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