Preparation and thermal shock resistance of high emissivity molybdenum disilicide- aluminoborosilicate glass hybrid coating on fiber reinforced aerogel composite

To develop a flexible reusable surface insulation for thermal protection system, MoSi ₂ -aluminoborosilicate glass hybrid coatings have been prepared on Al ₂ O ₃ fiber reinforced Al ₂ O ₃ -SiO ₂ aerogel composite by slurry dipping and rapid sintering method. The effect of MoSi ₂ content on radiative property and thermal shock behavior was investigated. The total emissivity values of all the coatings exceeded 0.85 in the wavelength of 0.8–2.5 μm. The M10 and M50 coatings were up to 0.9, which was due to the highest amorphous glass content of the M10 coating and the largest surface roughness of the M50 coating. The M30 coated composite showed the best thermal shock resistance with only 0.023% weight loss after 20 thermal shock cycles between 1473 K and room temperature, which was attributed to the similar thermal expansion coefficients between the coating and the substrate and the appropriate viscosity of aluminoborosilicate glass at 1473 K. The cracks resulted from CTE mismatch stress with different sizes formed and grew on the surface of M10, M40 and M50 coated samples, leading to the failure of the composites.