Ablation behaviour of coated Al 2 O 3f /Al 2 O 3 composites under oxyacetylene torch flame

Abstract

Oxide fibres have attracted considerable attention as protective layers for alumina composites. In this study, alumina (Al₂O_3f/Al₂O₃) matrix composites reinforced with continuous fibres were fabricated by a sol–gel process and were coated with Y₂O₃ or ZrO₂ to improve their ablation resistance. The ablation behaviour of the coated composites was analysed under the oxyacetylene torch flame test. The results suggested that the Y₂O₃ and ZrO₂ coatings as sacrificial barrier layers could protect the integrity of the composites. The linear ablation rate and mass ablation rate of composites with Y₂O₃ coating were 0.00251 mm s⁻¹ and 0.00143 g s⁻¹, respectively; the linear ablation rate and mass ablation rate of composites with ZrO₂ coating were 0.00142 mm s⁻¹ and 0.00112 g s⁻¹, respectively. After a 120 s ablation test at 2200°C, the coatings still showed a stable structure and a high protection performance.