| 摘要 |
PURPOSE:To extend the life of the surface layer of a casting mold by using the casting mold having the surface layer which is limited in the average grain size of inorg. powder and the content ratio of polytetrafluoroethylene to cast a lead alloy. CONSTITUTION:The practicable strength of the surface layer can be obtd. if said layer contains >=10W% polytetrafluoroethylene. Suitable porosity can be obtd. if the content thereof is <=80W%. A substantial fine pore characteristic is obtainable if the average grain size of the inorg. powder is <=50mu. The addition of a sublimatable benzoic acid or water soluble salt particles to said powder to increase the porosity is also a good alternative. Multi-layer coating is also possible by changing the content of the components at every spraying, by which the thermal conductivity can be controlled. The lead alloy having a long life which is suitable for a battery, etc. is thus obtd.
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