Ablation behaviour of coated Al₂O_3f/Al₂O₃ composites under oxyacetylene torch flame

Abstract

Oxide fibres have attracted considerable attention as protective layers for alumina composites. In this study, alumina (Al 2 O 3f /Al 2 O 3 ) matrix composites reinforced with continuous fibres were fabricated by a sol-gel process and were coated with Y 2 O 3 or ZrO 2 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 Y 2 O 3 and ZrO 2 coatings as sacrificial barrier layers could protect the integrity of the composites. The linear ablation rate and mass ablation rate of composites with Y 2 O 3 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 ZrO 2 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.