Anti-ablation performance of La2O3-modified ZrB2 coating on SiC-coated carbon/carbon composites

Abstract La2O3-modified ZrB2 coating was prepared on SiC-coated C/C composites by supersonic atmospheric plasma spraying (SAPS) with the aim of improving the anti-ablation performance of C/C composites. The effect of La2O3 contents on the anti-ablation performance were investigated. The results indicated that the 10 vol % La2O3–ZrB2 coating shows excellent anti-ablation performance. After ablation for 120 s under low heat flux oxyacetylene flame (2400 kW/m2), the linear ablation rate and mass ablation are only −0.0167 μm/s and −0.558 mg/s, respectively. After ablation for 30 s under high heat flux of oxyacetylene flame (4200 kW/m2), the coating still remains intact. The addition of 10 vol % La2O3 is capable of enhancing the anti-ablation performance of the ZrB2 coating. The La2O3 and La2Zr2O7 phases will be soften and melting during ablation, which can form a barrier to cover the surface and effectively prevent the erosion of oxyacetylene gas. Meanwhile, the generated ZrO2 particles play the role of pinning the molten layer, thus weakening the coating exfoliation by airflow erosion.