Thermal shock behavior and infrared radiation property of integrative insulations consisting of MoSi₂/borosilicate glass coating and fibrous ZrO₂ ceramic substrate

An integrative insulation consisting of a MoSi₂/borosilicate glass coating and a fibrous ZrO₂ ceramic substrate was explored for applications up to 1673K. The MoSi₂/borosilicate glass coating was prepared using the slurry dipping and subsequent firing method. The thermal shock behavior of the integrative insulation and the evolution of the surface morphology of the coatings for various thermal shock times were evaluated using confocal laser scanning microscopy (CLSM). The results revealed that the as-prepared coatings could maintain the dense structure and infiltrate into the substrate, forming a gradient structure and exhibiting good compatibility and adherence. After thermal cycling between 1673K and room temperature 15 times, the integrative insulation is also without micro cracks and spalling, and the weight loss is only 2.84%, revealing outstanding thermal shock performance. Additionally, the emissivity of the coatings reached 0.8 at room temperature, which was attributed to the synergistic effect of inter band absorption, crystal lattice vibration and the roughness of the coating. The gradual increase in the roughness resulted in the increase of the emissivity in 200-2500nm at room temperature, which was explained with a "circular grooves" model. These results imply that the integrative insulation can be a promising candidate material in high temperature application.