| 摘要 |
PROBLEM TO BE SOLVED: To improve the machinability (the ease of machining) of a valve guide material for an internal-combustion engine in terms of production cost and efficiency although conflicting properties of wear resistance to slide with valve at engine driving and machinability in an engine assembly stage are required of the valve guide material. SOLUTION: Machinability is almost doubled while keeping wear resistance superior to that of the conventional material by using a sintered alloy which has a composition consisting of 1.5-4% carbon, 6-20% copper, 0.1-2% tin, 0.1-0.3% phosphorus, <4%, in total, of enstatite and manganese sulfide, and the balance iron and also has a structure in which Fe-P-C alloy phases, copper-tin alloy phases, free graphite, enstatite and manganese sulfide are dispersed.
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