Enhancing the mechanical and insulation properties of CF/BPR composites by adding hollow silicate glass microspheres as an Interlaminar reinforcement

Improving the ablation and mechanical properties of ablative thermal protection composites by introducing modified fillers which simultaneously with an unavoidable increase in density. Balancing this increase in density while achieving lightweight properties is crucial for the development of effective ablative composites. In this paper, different contents of the hollow silicate glass microspheres (HSMs) are incorporated into MoSi 2 /mica-modified CF-BPR composites to investigate the impact of HSMs. The results show that HSMs play a positive role in reducing the density and thermal conductivity of the composite. The ablation and insulation properties of the 30 vol.% HSMs composites exhibit a mass ablation rate of 0.035 g/s and a linear ablation rate of 0.015 mm/s, alongside the lowest backside temperature. A significant improvement in flexural strength after static ablation at 1500 °C reached 82.59 MPa and maintained a relatively high level after 1600 °C. HSMs act as interlaminar skeletons, enhancing the shearing strength of the composite and facilitating the formation of a protective liquid phase around the carbon fibers to prevent oxidation. The increasing toughness of carbon fibers further enhances the mechanical strength of the composites.