Preparation and properties of TaSi2-MoSi2-ZrO2-borosilicate glass coating on porous SiCO ceramic composites for thermal protection

A TaSi2-MoSi2-ZrO2-borosilicate glass (TMZG) coating was prepared by a slurry method on a carbon fibre-reinforced porous silicon oxycarbide (SiCO) ceramic composite for thermal protection. The coating was well adhered to the substrate and showed a uniform thickness of approximately 375 µm. After thermal cycling from 1873 K to room temperature six times (total oxidation time of 180 min), the shape and dimension of the TMZG remain almost unchanged with no cracking or peeling of the coating surface. The TMZG-coated sample exhibits good oxidation resistance because of a molten SiO2 film with ZrSiO4 particles distributed on the outer layer of the coating. After ablation testing under an oxyacetylene flame at 1927 K for 90 s, the linear ablation rate of the TMZG coated sample are 8.33 × 10−4 mm/s. The whole coating retains integrity, preventing substrate ablation during the test. The TMZG coating with excellent temperature resistance shows broad applicability in thermal insulation materials.