VALVE SEAT MADE OF IRON-BASED SINTERED ALLOY FOR INTERNAL COMBUSTION ENGINES HAVING EXCELLENT HEAT RELEASE

To provide a valve seat for internal combustion engines compatible of excellent wear resistance and excellent heat release.SOLUTION: A valve seat made of an iron-based sintered alloy has a single-layer structure of only a functional member side layer or a two-layer structure in which the functional member side layer and a support member side layer are integrated via a boundary surface. The functional member side layer contains base material in which a base phase consisting of a fine carbide precipitation phase of 15% by volume or more, a tempered martensite phase or a pearlite-martensite phase of less than 80% by volume and a high alloy phase containing 10 to 30% of hard particles and 0.1 to 5.0% of solid lubricant particles dispersed therein by volume % relative to the whole volume of the base material and 10% by volume or more of Cu added by infiltration. The support member side layer is composed of a base material consisting of the base phase and solid lubricant particles further dispersed in the base phase and 15% by volume or more of Cu added by infiltration. Further, a plating film is provided on at least the outer peripheral surface of the valve seat.SELECTED DRAWING: None 【課題】優れた耐摩耗性と優れた熱引け性とを兼備する内燃機関用バルブシートの提供。【解決手段】機能部材側層のみの単層構造、または機能部材側層と支持部材側層とを境界面を介し一体化してなる２層構造の鉄基焼結合金製バルブシートとする。機能部材側層を、15体積％以上の微細炭化物析出相と、80体積％未満の焼戻マルテンサイト相、またはパーライト、マルテンサイト相および高合金相、とからなる基地相中に、基地部全量に対する体積％で、硬質粒子を10〜30％、固体潤滑材粒子を0.1〜5.0％分散させてなる基地部と、溶浸で添加されたCuを10体積％以上含む構成とする。また、支持部材側層を、基地相と、あるいはさらに該基地相中に固体潤滑剤粒子を分散させた基地部と、溶浸で添加されたCuを15体積％以上含む構成とする。そしてさらに、バルブシートの少なくとも外周面にめっき膜を有する。【選択図】なし