Microstructure, High-Temperature Wear Resistance, and Corrosion Resistance of Laser Cladded Co-Based Coating

Abstract

Co-based coating has been fabricated on Ti-6Al-4V (TC4) titanium alloy by laser cladding. The phase composition and microstructure of the coating were analyzed using metallurgical microscope (MM), scanning electron microscope (SEM), x-ray diffraction (XRD), energy-dispersive spectroscopy (EDS) and transmission electron microscopy (TEM), respectively. The microhardness, high temperature wear resistance and corrosion resistance of the coating were investigated by performance tests. The results show that the coating was mainly composed of CoTi, CoTi2 and Co0.5Cr1.5Ti crystalline phases and an amorphous phase. The microhardness of the coating was twice that of the titanium alloy substrate. The value of friction and wear coefficient of the coating was lower and more stable, and the wear mass loss decreased by 52% as compared with the substrate in the high-temperature friction and wear test. The oxidative wear mechanism in the condition of high temperature friction and wear was studied. Moreover, the coating exhibited better corrosion resistance than the substrate in both NaCl and H2SO4 electrolyte solutions.