Abstract: The degradation of protective performance at elevated temperatures remains a major limitation for application of organic coatings. In this study, for the first time, submicron low-melting glass (LMG) was combined with active nano-Ti powder to develop a novel oxidation-resistant silicone composite coating for protecting Ti-6Al-4V alloy at 650 °C. Compared with a control coating containing inert nano-TiO₂ (S-TO), the coating reinforced by nano-Ti powder (S-Ti) exhibited superior oxidation resistance. The nano-Ti powder functioned as an active pigment, consuming oxygen through oxidation and producing TiO₂ with a 73% volumetric expansion. This expansion synergized with the viscous LMG-derived glass phase, enabling the in-situ repair of holes formed by the submicron LMG particles, thereby enhancing the coating density. Consequently, the S-Ti coating achieved lower porosity (6.1% vs. 14.0%), reduced oxygen diffusion flux, and suppressed substrate oxidation kinetics (rate constant: 5.4×10^-7 mg² cm^-4 s^-1 vs. 8.9×10^-7 mg² cm^-4 s^-1 for S-TO). After oxidation for 300 h, no oxide scale was observed on the substrate surface (detection limit: 1 µm).

Key words: Submicron low-melting glass, Nano-Ti powder, Silicone composite coating, Oxidation resistance, Porosity, Coating density