Experimental analysis on tribological behavior of Co/TiC/CaF2/Y2O3 composite coating developed by plasma transferred arc (PTA) cladding technique on AZ91D Mg alloy substrate

In this study, Co/TiC/CaF2/Y2O3 composite coating was fabricated on AZ91D Mg alloy by plasma transferred arc cladding (PTA) technique. The composite coating was fabricated with parameters as PTA current of 40 A and scan speed of 150 mm/min. The coating powders consisted of Co (60 wt%) and Y2O3 (1 wt%), with varying amounts of TiC (ranging from 34 wt% to 19 wt%) and CaF2 (ranging from 5 wt% to 20 wt%). An investigation on the effect of TiC and CaF2 content on the mechanical and wear performance of Co/TiC/CaF2/Y2O3 composite coatings has been conducted. Characterization of the coatings such as microstructure, elemental analysis, and phase analysis were investigated by scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) respectively. Results showed that the phase constituents in the coatings were TiC, CoO, CoTi, Co2Y3, YTiO3, CoYC, TiO2, and CaF2. The maximum average microhardness of the clad layer was about 1162HV(0.05), while the average microhardness of AZ91D Mg alloy substrate was about 68HV(0.05). Based on this study, it has been found that the coating has 17 times more hardness than the AZ91D Mg substrate. Also, it can be concluded that the coating has nearly 37 times higher wear resistance than the AZ91D Mg alloy substrate.