MoSi2-borosilicate glass coating on fibrous ceramics prepared by in-situ reaction method for infrared radiation

Highlights: • MoSi₂-borosilicate glass coating was prepared by an in-situ reaction method. • The coating tightly adhered to the substrates by mechanical interlocking. • The coating had enhanced impact resistance and high emissivity. • The operating temperature of the coating was up to 1500 °C. • Thermal shock failure mode of the coating was interfacial fracture. MoSi₂-borosilicate glass coating with MoSi₂ as emittance agent was prepared on mullite fibrous ceramics for enhanced superficial infrared radiation via an in-situ reaction method. The phase and structure evolutions during sintering were studied in detail. The infrared radiating property, impact resistance, thermal shock resistance and thermal endurance of the coating were investigated comprehensively. The results show that the coating was dense and flat, and it tightly adhered to the substrate by mechanical interlocking. During the sintering process, the low-temperature oxidation of MoSi₂ was restrained due to the package of binder phase formed below 500 °C, and the coating was fully densified via the viscous flow of molten Si. The total emissivity of the as-prepared coating was higher than 0.85 and the emissivity at low wavelength was higher than 0.9. The impact resistance was preferable attributed to the reinforced transition layer at the interface. The coating went through 30 thermal cycles between 1500 °C and 25 °C without cracking and spalling. The total emissivity declined merely by 4% after oxidation at 1500 °C for 50 h, which was influenced by the MoSi₂ content and the surface roughness of the coating.