Preparation and properties of ZrB₂-SiC compound ceramic coating for C/C-SiC composites

A ZrB₂-SiC ceramic coating was prepared on C/C-SiC composites by slurry painting and high temperature sintering to improve the ablation property of C/C-SiC composites at ultra high temperatures. The phase composition and microstructure of the ZrB₂-SiC coating were analyzed by EDS and SEM. The mechanical and ablation properties of the coatings were investigated. The results show that the tensile strength, flexural strength and shear strength of the C/C-SiC composites protected by ZrB₂-SiC coatings are 147 MPa, 355 MPa and 21.9 MPa, respectively. The mechanical properties of the coated C/C-SiC composites are little lower than the counterpart properties of the uncoated C/C-SiC composites. The coated C/C-SiC composite has an outstanding ablation property. After ablation by oxyacetylene torch test at a heat flux of 3 200 kW/m² for 600 s, the coated sample has an average mass ablation rate of 0.001 mm/s and an average linear ablation rate of 0.0006 g/s.