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 (∼40 μm) increased significantly by 285 % compared to the PEO coating (∼14 μm). The microstructural evolution and isothermal oxidation performance of the PEO and SiC-SiO₂ nano-composite coating were comparatively investigated at 800 °C. After 100 h, the thickness gain of the SiC-SiO₂ nano-composite coating (∼14 μm) was lower than that of the PEO coating (∼26 μm). 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.