Enhanced hot corrosion resistance and thermal radiation property of NbSi2/Nb2O5-SiO2/SiC ceramic coating for niobium alloys thermal protective system.

A NbSi 2 /Nb 2 O 5 -SiO 2 /SiC multilayer coating was developed on niobium alloys to improve the hot anti-corrosion and infrared thermal radiation performance simultaneously. This novel modified silicide coating includes a NbSi 2 inner layer, a Nb 2 O 5 -SiO 2 pre-oxidation intermediate layer, and a SiC particle deposition and sintering outer layer, showing a strong multilayer synergistic. This multilayer design strategy endows the coating a high emissivity above 0.9 at 700 °C across the entire range of wavelength (3–20 μm), significantly enhancing the infrared thermal radiation performance than that of the NbSi 2 coating and PEO-coating. Accordingly, the enhanced infrared radiation performance is ascribed to the synergistic effects of vibrational absorption between the Nb 2 O 5 , SiO 2 and SiC phase in the ceramic outer layer over multiple bands, as well as the porous surface structure of LPDS-coating; Meanwhile, the as-prepared LPDS-coated specimen exhibits an excellent anti-corrosion performance with a mass gain of −0.56 mg/cm2 under the hot corroded environment for 100 h. The improved hot anti-corrosion performance is main the result of a synergistic effect between a dense pre-oxidation layer and a continuous SiO 2 film layer with self-sealing, as well as the SiC providing an extra Si source substantially. A novel NbSi 2 /Nb 2 O 5 -SiO 2 /SiC multilayer protective ceramic coating has been designed and prepared on silicide coating by using a one-step liquid-plasma-assisted particle deposition and sintering (LPDS) technology, which achieves a superior hot corrosion resistance and infrared thermal radiation performance. [Display omitted] • NbSi 2 /Nb 2 O 5 -SiO 2 /SiC coating is designed and constructed through a new multilayer co-growing strategy. • The incorporation of SiC nanoparticles gives superior hot corrosion resistance of the coating. • The enhanced hot corrosion resistance is mainly ascribed to the formed SiO 2 molten salts barrier layer. • The incorporation of SiC nanoparticles improves the high-temperature broadband emissivity (>0.9). [ABSTRACT FROM AUTHOR]