Microstructure and high-temperature oxidation resistance of Ti-6Al-4V alloy with in-situ SiC-SiO2 nano-composite coating by LPDS technique

A SiC-SiO2 nano-composite coating was prepared via a novel liquid-phase plasma-assisted particle deposition and sintering (LPDS) method to enhance the oxidation resistance of the Ti-6Al-4V alloy. For comparison, a conventional plasma electrolytic oxidation (PEO) ceramic coating is fabricated on the Ti-6Al-4V alloy. The microstructure and formation mechanisms of both ceramic coatings were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results indicated that the thickness of the SiC nano-composite coating (similar to 40 mu m) increased significantly by 285 % compared to the PEO coating (similar to 14 mu m). The microstructural evolution and isothermal oxidation performance of the PEO and SiC-SiO2 nano-composite coating were comparatively investigated at 800 degrees C. After 100 h, the thickness gain of the SiC-SiO2 nano-composite coating (similar to 14 mu m) was lower than that of the PEO coating (similar to 26 mu m). The improved oxidation performance is primarily attributed to the outermost layer containing abundant SiC nanoparticles, which transform into SiO2 during the oxidation process and effectively inhibiting the inward penetration of oxygen.