Jianfang Sun

Phosphate ceramic coatings are promising protective materials for metallic components exposed to corrosive and sliding environments, but their brittleness, structural defects, and weak adhesion limit their long-term performance, especially in sulfur-containing media. In this study, methyltriethoxysilane (MTES) was introduced into phosphate ceramic coatings on 321 stainless steel to construct an organic–inorganic hybrid structure with enhanced corrosion and tribocorrosion resistance. MTES participated in hydrolysis and condensation reactions, forming Si-O-Si and P-O-Si networks without altering the main crystalline phases. The optimized coating containing 1.0 g MTES exhibited a denser microstructure, improved particle distribution, and stronger coating–substrate adhesion, with bonding strength increasing from 2.98 to 6.40 MPa. Compared with the substrate, the optimized coating reduced the corrosion current density by approximately 95% in 0.6 mol/L NaCl solution and approximately 90% in 0.6 mol/L NaCl + 0.1 mol/L Na2S2O3 solution. Under dry sliding conditions, the wear rate decreased by 43.6%, while under tribocorrosion conditions, the wear rate decreased by approximately 34%. The enhanced performance was mainly attributed to the MTES-induced phosphate–siloxane hybrid network, which improved coating compactness and inhibited corrosive ion penetration and wear.