Interface improvement of plasma cladded Ni-based coating on copper induced by substrate preheating

Abstract

To further clarify the characteristics of plasma cladding on copper surface, the effect mechanism of preheating temperature on the interfacial connection of Ni-based coatings was investigated. Results showed that metallurgical bonding can be achieved between coating and copper substrate only when the preheating temperature reached at least 500°C. Without preheating, the heat of the plasma arc was conducted away by the copper with high thermal conductivity, making it difficult to form a molten pool. At low temperatures (300°C and 400°C), the copper oxides formed on copper surface during preheating had poor wettability with the liquid Ni-based alloy, resulting in unreliable interfacial connection. Properly increasing (above 500°C) the preheating temperature can promote the removal of copper oxides, thereby improving the interfacial wettability. Moreover, to avoid performance degradation caused by excessive dilution ratio, controlling the preheating temperature at about 600°C is more appropriate.