Effect of copper on the heat erosion mechanism of carbon/carbon composites

Precursor of copper (Cu) was introduced into 2D needle-punched carbon felts at room temperature to fabricate carbon/carbon (C/C) compotes modified with Cu (C/C[sbnd]Cu). Ablation property, heat erosion mechanism and flexural properties of C/C[sbnd]Cu composites were investigated. Bad wettability between copper and carbon faded their interface bonding and made flexural strength of C/C composites decreased by 11.5% in Z direction and 9.7% in X direction. By introducing the in-situ growth of CNTs, its flexural strength was back to that of C/C composites. The ablation test results showed that C/C[sbnd]Cu composites exhibited better ablation resistance than pure C/C composites. After ablation for 120 s, its mass and linear ablation rate decreased from 2.30 mg/s and 7.00 μm/s to 1.55 mg/s and 3.45 μm/s comparing with that of pure C/C composites. Analyses of ablation behavior depending on temperature and ablated surface micrographs indicated that copper liquid droplets escaped from sub surface and were blown away from ablation central zone to fringe zone, which all absorbed lots of heat and made the temperature of central zone decreased, keeping the temperature of ablation surface stable. Moreover, the central zone temperature of C/C[sbnd]Cu composites and C/C composites was 1943 °C and 2172 °C, respectively. Such high temperature (1943 °C) made copper evaporate with a small mount which also take away much heat. This temperature changes in ablation surface slowed the oxidation of carbon and made C/C[sbnd]Cu composites have less ablation rate.