| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent the erosion of a die used to a die casting or a low pressure casting of an Al alloy with a surface treatment. SOLUTION: On the surface of the die produced with a tool steel for high temp. service, and at least on a part having the fear of affection of the erosion, a protecting layer having >=5μm thickness is formed. The protecting layer is desirable to be composed of Nb oxide. However, in the case of occupying >=30% area ratio of the Nb oxide, the rest can be occupied with the layer having Ni or Co based heat resistant alloy. The protecting layer of the Nb oxide can be formed by executing the oxidizing treatment after forming Nb or NbC film with a plasma thermal-spraying, discharging build-up or PVD. As the method for sticking the protecting layer composed of the Nb oxide and the Ni base or Co base heat resistant alloy, the plasma thermal-spraying is applied to the mixed powder of the Nb or NbC powder and the Ni or Co based heat resistant alloy powder, and then, the oxidizing treatment can be executed to this formed thermal-spraying film.
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