Evaluation of Microstructure, Wear and Corrosion Resistance of Inconell 625 Clad Layer on Copper Substrate

Improvement of copper surface properties, such as wear resistance and corrosion resistance, increases the application of this metal in various industries .For this purpose, Inconnell 625 alloy was coated with Gas Tangsten Arc Welding (GTAW) on copper. Phase analysis and solidification behavior of coating were performed using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the coating structure contains the γ phase, with the secondary products of niobiumrich. Due to the full solubility of nickel and copper in solid state, it was observed that the region created between the coating and the substrate has a chemical composition of Cu-24.26 Ni-9.31 Cr-5.77 Mo and is free from metallurgical defects. The microhardness of sunstrate and coating was measured 50 and 338 vickers, respectively. In order to investigate the wear behavior of the coating and the substrate, the pin on disk test was used at ambient temperature. The wear surfaces produced at ambient tempreture characterised at micro-scale level using SEM and EDS. The presence of coating increased wear resistance of about 85%, which can be attributed to the change in the wear mechanism from delamination wear (related to copper) to oxidation wear (related to inconell 625). The oxide layer formed from the wear pair, in addition to reducing the wear rate, reduced the friction range from about 0.2 - 1.5 (related to copper) to 0.3 - 0.8 (for inconell 625). The study corrosion property of coating and substrate was also done by polarization test. The results showed a significant increase corrosion resistance of copper in the presence of this coating and corrosion current decreased from 239 nA/cm2 to 0.27 nA/cm2 .