Multifunctional TiO₂-SiO₂/SiBCN/ZrO₂ coating on titanium alloy: Enhanced high-temperature oxidation resistance and thermal radiation performance

With the development of aerospace technology, the thrust-to-weight ratio of aircraft has continuously improved, leading to elevated service temperatures for titanium alloys used in hot-end components of aerospace vehicles and consequently intensifying high-temperature oxidation. In this study, a two-step liquid-plasma-assisted particle deposition and sintering (LPDS) in-situ film-forming process is innovatively proposed to construct a novel composite coating on the surface of TA15 titanium alloy. The composite coating consists of a TiO₂-SiO₂ transition layer, an oxygen-consuming SiBCN sublayer, and an oxygen-blocking ZrO₂ outer layer, which synergistically suppresses oxidation-induced damage. The LPDS process provides stable discharge sites on the surface of the SiBCN layer, enabling secondary in-situ growth of the ZrO₂ layer and resulting in a thick coating with an overall thickness of ∼92 μm. After oxidation at 800℃ for 100 h, the oxidation mass gain of TiO₂-SiO₂/SiBCN/ZrO₂ coating (5.76 mg/cm⁻²) is only 5.85% of that of TA15 alloy (98.51 mg/cm⁻²). The excellent oxidation resistance is mainly attributed to the dense ZrO₂ outer layer and the formation of a self-sealing glass phase at high temperature. Moreover, the multi-layer design endows the coating with a high emissivity exceeding 0.95 in the wavelength range of 8–14 μm, presenting outstanding radiative heat dissipation performance. The improved infrared radiation performance is ascribed to the synergistic effect of mutual doping and multi-band vibrational absorption among ZrO₂, SiBCN, SiO₂ and B₂O₃ phases in the ceramic coating, as well as increased infrared absorption induced by the rough surface morphology.