Preparation and ablation behavior analysis of non-equimolar Cf/(Hf1/2Zr1/3Ti1/6)C composites under oxyacetylene flame with different heat fluxes

In this study, the synthesis of Cf/(Hf1/2Zr1/3Ti1/6)C non-equimolar middle-entropy composites was reported through precursor infiltration and pyrolysis processing for the first time. The pyrolysis process of the (Hf1/2Zr1/3Ti1/6)C precursor was examined by XRD, while the resultant ceramic was characterized by SEM, EDS, and TEM. The results showed that precursor-derived (Hf1/2Zr1/3Ti1/6)C powders were characterized by single-phase and uniformly distributed elements from microscale to nanoscale. The Cf/(Hf1/2Zr1/3Ti1/6)C composites exhibited a density of 2.741 g/cm3 and a porosity of 11.49 vol%. The various elements were uniformly distributed throughout the material. It also demonstrated outstanding mechanical properties, with a flexural strength of 219.34 MPa and a modulus of 24.82 GPa. At the heat flux of 3 MW/m2, the oxides after ablation were inadequate to fully envelop the substrate. When the heat flux increased to 4 MW/m2, a dense Hf-Zr-Ti-O multiphase oxide layer was formed on the surface of the sample, providing the internal Cf/(Hf1/2Zr1/3Ti1/6)C composites against further ablation. At the heat flux of 5 MW/m2, (Hf, Zr)TiO4 was severely consumed. Our research expands the application scope of non-equimolar middle-entropy composites in the domain of ultra-high temperature ablation resistance.