Study on Microstructure and Properties of Laser Cladding AlSi12/TiN Composite Coating on Rare Earth Magnesium Alloy

AlSi12/TiN composite coating on the surface of Mg-Gd-Y-Zr magnesium alloy was prepared by high-speed laser cladding technology, and the effects of different contents of ceramic strengthening on the microstructure and properties of the composite coating were studied. The microstructure and cladding layer of TiN coatings with different contents of ceramic strengthening phase were studied by optical microscope (OM), X-ray diffractometer (XRD), scanning electron microscope(SEM), friction and wear experiment and electrochemical analysis and testing.The results show that, the composite coating is mainly composed of α-Mg, Mg₂Si dendrites, Al₁₂Mg₁₇, Al₃Mg₂ intermetallic compounds and TiN strengthening phase. Due to the presence of the reinforced second phase and the refined grains, the friction coefficient, Vickers hardness and bonding strength of the AlSi12/TiN composite coating reach 0.45, 210 HV0.1 and 40 MPa respectively.In addition, compared with the magnesium alloysubstrate, thecorrosionpotentialisincreasedby 683 mV, and the self-corrosion current density is reduced by 2 orders. The AlSi12/TiN composite coating with high bond ing strength can be prepared on the surface of Mg-Gd-Y-Zr magnesium alloy by laser cladding technology. The coating with a suitable content of strengthening phase can significantly improve the wear resistance and corrosion resistance of the substrate surface.