| 摘要 |
PURPOSE:To enhance thermal conductivity of a valve and to restrain a temperature rise of the valve by coating the outer surface of a valve formed by heat- resisting steel with a compound phosphate coat where copper is made eutectic. CONSTITUTION:In case of a suction valve 3 having a stem portion 6, a neck portion 7 and a shade portion 8 solidly formed by ferritic heat-resisting steel, after the suction valve 3 is subjected to degreasing treatment or washing, the outer surface of the valve is coated with a compound phosphate coat 11 where copper is made eutectic. As the phosphate coat 11, manganese phosphate is optimum, and in order to produce this manganese phosphate, the suction valve 3 is dipped in a compound water solution of manganese primary phosphate end copper salt (acid copper nitrate) during a fixed period of time. In case of the thus formed valve, thermal conductivity is improved, the use of expensive heat-resisting steel can be stopped, and the temperature of the valve can be kept low without lowering of burning temperature.
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