Mechanical properties and oxidative ablation behaviors of polysilazane-modified phenolic resin aerogel/carbon fiber fabric composites

Nanoporous composites have been extensively applied in aerospace applications for their outstanding thermal insulation and ablation resistance. A ceramizable polysilazane (PSZ)-modified phenolic resin (PSZ-PR)/carbon fiber fabric (PSZ-PR/CF) aerogel composite was synthesized through ambient pressure drying (APD). The homogeneous nanopore structure and improved thermal stability of the PSZ-PR aerogel matrix provided the composites with good performance (thermal conductivity as low as 0.126 W/(m·K)). The PSZ-PR/CF composites achieved high compressive strength (up to 43.75 MPa), tensile strength (59.22–124.75 MPa), and bending strength (23.35–97.94 MPa). Furthermore, the generation of ceramization products during the oxyacetylene flame ablation process, specifically SiC and Si₃N₄, enhanced the ablation resistance of PSZ-PR/CF composites: the linear ablation rates are as low as 0.112 and 0.018 mm/s at 4.18 MW/m² (20 s) and 1.20 MW/m² (120 s) of oxyacetylene heat flow, respectively. The corresponding maximum back temperatures are only 51.0°C and 60.3°C. Notably, the carbon/ceramic network is still present in the ablation layer to protect the carbon fibers from oxidation. This ceramizable PSZ-PR/CF composite has good potential for application in the field of thermal protection. Highlights: PSZ improves thermal stability and ablation properties of PSZ-PR/CF. The PSZ-PR/CF composites exhibit excellent mechanical and ablation properties. The ceramic products improve the scouring resistance of aerogel matrixes. The ceramizable PSZ-PR/CF was prepared by low-cost ambient pressure drying.