Lightweight and multiscale needle quartz fiber felt reinforced siliconoxycarbide modified phenolic aerogel nanocomposite with enhanced mechanical, insulative and flame-resistant properties

Lightweight and multiscale nanocomposites are considered to be the most promising materials applied in the field of advanced aerospace and modern building industry, owing to their outstanding mechanical, thermal and flame-resistant properties served in high-temperature oxidizing environments. Herein, a novel siliconoxycarbide (SiOC) modified needle quartz fiber felt reinforced phenolic resin nanocomposite (SiQF/PR) with a hierarchical macro-/micro-/nano-scaled structure is reported. The as-prepared highly porous SiQF/PR nanocomposite exhibits a multiscale three-dimensional network and the micro-sized SiOC particles, derived from the hydrolysis of methyltrimethoxysilane (MTMS) and dimethyldiethoxysilane (DDS), are uniformly incorporated into the phenolic aerogel. The resultant nanocomposite has a bulk density of 0.30–0.35 g/cm³, and the maximum compressive strength reaches 4.20 MPa and 3.34 MPa in xy and z directions, respectively. Thermal stability and oxidation resistance experiments show that the SiQF/PR multiscale composite has a good ablation and heat insulation performance under oxyacetylene test condition, and the backside temperature of SiQF/PR is only 55.5 °C under 1.8mw/m² for 120 s, and line ablation rate of SiQF/PR multiscale nanocomposite decreases by 20.1% at 1.8 MW/m² and 59.5% at 0.4 MW/m² compared to non-SiOC modified composite. These results indicate that the lightweight SiQF/PR nanocomposite fabricated by this method is very suitable for architectural or aerospace applications as high-performance insulation material.