Enhancement of the Ablation Properties of Silica/Phenolic Resin Composites by SiC/Si3N4 Multiphase Structures

Abstract

This work mainly studied the influence of SiC and Si3N4 composite fillers on the ablation performance of silica/phenolic composites. The effect of Si3N4 content on the mechanical and ablative properties of the composites was investigated, and the bridging effect between the two different ceramic fillers was analyzed. The results indicated that the mechanical properties and ablation properties of the composite were improved due to the combined effect of the SiC and Si3N4. When the content of Si3N4 was 36phr, the flexural strength at room temperature was 114.6 MPa, the flexural strength after 1200 °C treatment was 18.38 MPa, and the linear ablation rate was 0.011 mm/s in the 1600 °C oxyacetylene ablation test for 30s, while the flexural strength without Si3N4 at room temperature was 105.4 MPa, the flexural strength after 1200 °C treatment was 10.35 MPa, and linear ablation rate was 0.061 mm/s in the 1600 °C oxyacetylene ablation test for 30s. The bridges between the Si3N4 and SiC ceramic fillers can form SiO2, SiCN and Si2N2O in the high temperature environment, which helps fill the pores on the surface of the composite, forming an effective protective layer structure and improving the high temperature and erosion resistance of the composites.