Environmental barrier coating (EBC) materials that are resistant against molten calcia-magnesia-aluminosilicate (CMAS) corrosion are urgently required. Herein, multicomponent rare-earth (RE) disilicate ((Yb_0.2Y_0.2Lu_0.2Sc_0.2Gd_0.2)₂Si₂O₇, (5RE)₂Si₂O₇) was investigated with regard to its CMAS interaction behavior at 1400 ℃. Compared with the individual RE disilicates, the (5RE)₂Si₂O₇ material exhibited improved resistance against CMAS attack. The dominant process involved in the interaction of (5RE)₂Si₂O₇ with CMAS was reaction-recrystallization. A dense and continuous reaction layer protected the substrate from rapid corrosion at high temperatures. The results demonstrated that multicomponent strategy of RE species in disilicate can provide a new perspective in the development of promising EBC materials with improved corrosion resistance.

Carbon fiber reinforced silicon carbide-hafnium carbide (C/SiC-HfC) composite was prepared by precursor infiltration and pyrolysis process. Then, ablation behavior of C/SiC-HfC was evaluated in plasma wind tunnel. It was found that oxide layer formed during ablation significantly influenced the surface temperature. Formation of dense HfO₂-SiO₂ layer under low heat flux led to stable surface temperature. Silica (SiO₂) on the surface was gradually consumed when heat flux increased, resulting in conversion of HfO₂-SiO₂ on the surface to HfO₂. Converted HfO₂ with high catalytic coefficient absorbed more energy, causing gradual increase in the surface temperature. Formed oxide layer was destroyed at high heat flux and high stagnation point pressure. After carbon fiber lost the protection of HfO₂-SiO₂ layer, it burned immediately, leading to surface temperature jump.