| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that shrinkage occurs when raw powder of a two layer structure sintered iron-base valve seat is press-formed and the green compact is sintered, the shrinkage of the sintered body increases with use of highly-alloyed raw material, dimensional shrinkage of the sintered body (product blank) with respect to a die dimension increases, and a dimension of a highly-alloyed seat layer having large shrinkage and a dimension of an inexpensive material support layer having small shrinkage become different except joint surfaces if the support layer not contacting a valve is made of inexpensive material. SOLUTION: The support layer 2 made of Fe-based material not contacting the valve has one or more of nonmetal powder particles and high hardness metal particles dispersed in an iron-based base consisting primarily of Fe. Powder particles for reducing compressibility at the time of press forming are added into the iron-base low alloy base of the support layer to increase springback and lower a density of the compact. This technique increases the dimensional shrinkage percentage of the compact at the time of sintering and the dimensional shrinkage percentage almost equal to a seat layer 1 is obtained. COPYRIGHT: (C)2006,JPO&NCIPI
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