| 摘要 |
PROBLEM TO BE SOLVED: To improve the erosion resistance and the heat cycle resistance of a casting member used in the contact part with molten metal and the heat retaining property of the molten metal by forming a chromium nitride film having a specific density on the surface of a base material of the casting member. SOLUTION: The density of the chromium nitride film is regulated to >=6.40 g/cm<3> N content in the chromium nitride film is 30-55 atomic % and further, it is desirable that the base material of the member for casting is made of Ti or Ti alloy. The chromium nitride film is formed by a cathode discharging type AIP method (arc ion plating method) and further, this member is desirable to be used for molten Al or Al alloy. Since the AIP method is executed so as to vaporize and ionize a target with the large current arc, the ionizing efficiency is high and the chromium nitride film excellent in closeness and adhesivility can be obtd. The N in the film can be adjusted by adjusting the pressure of reaction gas, and since the coating temp. is 300-500 deg.C, which is lower than theβtransformation point of the Ti or Ti alloy at 800-950 deg.C, the thermal stress and the lowering of strength are not developed in the Ti or the Ti alloy.
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