Carbon fiber-reinforced resorcinol–formaldehyde (C-RF) composites were modified with different weight ratios of zirconium diboride (ZrB2) to realize ZrB2–C-RF composites. Mechanical properties, thermal stability, and ablation resistance of ZrB2–C-RF composites were found to be optimum when the ZrB2-to-RF weight ratio is 0.05:1. Thermogravimetric analysis has shown that with optimum ZrB2 content, pyrolysis residue of resorcinol–formaldehyde got enhanced by 36%, indicating enhanced thermal stability of the system. Ablation mechanisms of composites after oxyacetylene flame exposure were derived from the inferences obtained from X-ray diffraction and microstructure analysis. It was found that the formation of high-temperature species, such as ZrO2 and ZrC, due to decomposition of ZrB2 and subsequent reaction products with char resulted in increased ablation resistance of the composites. During ablation, ZrB2–C-RF composites displayed low char formation and low erosive losses, confirming that these composites are promising for rocket motor nozzle and heat shielding/thermal protection system applications.

The re-entry phase of a space vehicle demands thermal shielding against the heat elicited by an aerodynamic heating process. The quantity of heat spawned in such process is close to 11.35 × 10 5 kJ m −2 and temperature reaching 8000 °C at the stagnation point on the surface of the re-entry vehicle. Ablative materials are effectual for heat shielding re-entry vehicles, and their performance is improved by various physicochemical techniques. Utilization of ultrahigh-temperature ceramics to enhance the performance of ablative materials has set a new milestone in heat shielding applications. The article briefly introduces the conditions that prevail during a re-entry phase, discusses thermophysical properties that are to be adorned by ablative materials other mere thermal insulation. This review article uniquely discusses the effect of the selection of ceramic filler system on the formation of an oxidation layer, the emissivity of the oxidation layer and thermophysical behavior of the oxidation layer.

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