Microstructural, thermal and ablative properties of TiB₂ modified carbon fiber reinforced resorcinol formaldehyde composites for thermal protection of aerospace vehicle

Ablative polymeric composites were fabricated using vacuum impregnation and hot press molding techniques. The composites consisted of needled carbon fiber felt as the reinforcing material and resorcinol-formaldehyde (RR) or boron-modified resorcinol-formaldehyde resin (RRB) as the matrix. Different weight percentages of titanium diboride (TiB2) were incorporated as a filler. The ablation mechanisms of the composites were derived from SEM-EDS, XPS, and XRD analysis of char layers formed after exposure to an oxyacetylene flame. The composites displayed excellent thermal insulation properties during the oxyacetylene test. The back surface temperatures ranged from 24.8 to 26.8 degrees C, indicating minimal heat penetration through the composites. This composite demonstrated a linear ablation rate (LAR) of 0.0053 mm/sec, a mass ablation rate (MAR) of 0.0195 g/sec, and a charring rate (CR) of 0.0543 mm/sec. During ablation, the low LAR, MAR, and CR values of C-RRB-T composites confirm that these composites are promising for thermal protection system applications in aerospace.Highlights Resorcinol formaldehyde matrix was modified with boron and filler TiB2. Composites were fabricated using vacuum impregnation and hot press molding. The thermal stability and char yields of the composites increased with TiB2. The addition of TiB2 to the C-RRB composite improved the ablation properties.