Ablation and mechanical behaviour of C/C composites under an oxyacetylene flame and tensile loading environment

Abstract

Carbon/carbon (C/C) composites impress with their excellent high-temperature mechanical properties. In this paper, in order to simulate the complex service conditions of aerocraft thermal protection systems, an experimental platform for simultaneous ablation and tension was designed. The mechanical and ablation properties of the C/C composites were tested under an oxyacetylene flame at heat flux of 2185 kW/m2. Meanwhile, the mechanism of mutual influence of ablation and tensile loading was revealed by microstructural characterisation. By comparing the tension-only and ablation-only conditions, the results show that the strength of the C/C composites under ablation conditions decreased by 52.0%, which was associated with the crack propagation and porosity increase caused by flame. The tensile loading increased the linear and mass ablation rates by 21.8% and 82.9%, respectively, which was due to the interfacial damage caused by tensile stresses provides more channels for flame to enter the material interior, thus accelerating oxidative ablation.