High emissivity MoSi₂–TaSi₂–borosilicate glass porous coating for fibrous ZrO₂ceramic by a rapid sintering method

A MoSi₂-TaSi₂-borosilicate glass porous coating was designed and prepared on fibrous ZrO₂ceramic with slurry dipping and subsequent rapid sintering method. The microstructure, radiative property and thermal shock behavior of the coating have been investigated. The results show the coating presents a top Ta-Si-O compound glass layer and a porous MoSi₂-TaSi₂-borosilicate glass inner layer. The total emissivity of the coating is up to 0.88 in the range of 0.3–2.5 μm and 0.87 in the range of 2.5–15 μm at room temperature. The increased surface roughness leads to the increased emissivity, which can be explained by “V-shaped grooves” model. The coating turns into a dense structure and presents an interlocking structure in the interfacial layer after thermal cycling between 1673 K and room temperature 10 times, exhibiting excellent thermal shock resistance, which was attributed to the synergistic effect of porous structure and the match of thermal expansion coefficient between the coating and substrate.