Fabrication and Characterization of Ni60A Alloy Coating on Copper Pipe by Plasma Cladding with Induction Heating

Plasma cladding coupled induction heating was developed and successfully used to fabricate Ni60A coating on the surface of copper pipe. By matching the swing arc with the rotating copper pipe, the cladding efficiency was as high as 32.72 mm2/s. From the head to the tail of the coating, the wear resistance changed from 4.5 to 1.8 times that of pure copper. During the cladding process with constant current, the surface temperature of the cladding zone and the bath depth gradually increased. The corresponding dilution ratio increased, accompanied by the widening of the interface transition zone and the growth of precipitated phases (CrB and Cr23C6). Due to the gradient change of composition, the coating can be regarded as an in situ synthesized gradient coating. The critical point of sudden change of temperature in cladding zone was 850 °C, at which point the wear mechanism changed from abrasive wear to adhesive wear. The proper surface temperature of cladding zone should be controlled within 600–850 °C, which can be achieved by matching the cladding current and induction heating power. Results indicated that plasma cladding coupled induction heating is a potentially effective method to prepare high-quality coating on the surface of a large-complex-curved copper component.