Effect of SiC on ablation mechanism and morphological evolution of in situ synthesized ZrB2–SiC composites

Abstract

In the current study, the synthesis of ZrB2–SiC composites was carried out by in-situ reduction of ZrO2, B4C, Si, and graphite (C) followed by hot pressing at 1500 °C. The thermodynamic calculation revealed the feasibility of the reactions. The amount of SiC increased from 12 wt% to 30 wt% as the B4C/Si and C/Si molar ratio decreased from 1.0 to 0.4 and 4.0 to 2.2, respectively. In situ formed SiC particles are homogeneously distributed on ZrB2 grains, which inhibits grains growth and enhances densification. The HR-SEM and EDS analysis revealed the microstructure and elemental analysis of the composite before and after the ablation test. The SiC particle provides better dimensional and thermal stability during ablation at 2600 °C due to the formation of SiO2 and ZrO2/SiO2 layers on the surface of oxidized composites. Also, the SiO2-dense layer protects the base composite due to the low diffusion coefficient of oxygen and the development of the SiC-depleted layer. © 2023 Elsevier B.V.