| 摘要 |
<p>A highly wear-resistant valve seat for use in an internal combustion engine is provided. A feedstock powder for forming a valve-contacting-side layer is obtained by mixing an iron powder, a hard-particle powder, and a graphite powder. Said feedstock powder may also contain an alloy-element powder and/or a solid-lubricant-particle powder. The feedstock powder is formulated such that after sintering, a base part contains 0.3-2.0 mass% carbon and a total of up to 70 mass% of one or more of the following elements, with the remainder comprising iron and unavoidable impurities: cobalt, silicon, nickel, molybdenum, chromium, manganese, sulfur, tungsten, and vanadium. Some or all of the hard-particle powder has a mean particle diameter between 15 and 50 µm, inclusive, and the iron powder also has a mean particle diameter between 15 and 50 µm, inclusive, such that after sintering, the structure of the base part is such that hard particles constitute 10-65% of the total mass of the valve-contacting-side layer and are dispersed with a density of at least 1,000 particles/mm2. This makes it possible to uniformly disperse a hard-particle phase throughout a base phase of a sintered body, yielding an iron-based sintered valve seat that exhibits excellent wear resistance and strength.</p> |
