Calcium-ferrum-alumina-silicate (CFAS) corrosion behavior of Lu4Hf3O12 ceramics at 1400°C

In this work, the corrosion behavior of rare-earth Lu₄Hf₃O₁₂ ceramic when exposed to a CaO-FeO_1.5-AlO_1.5-SiO₂ (CFAS) environment at a temperature of 1400°C was investigated, with a focus on exploring the associated phase transformation, microstructure evolution, and corrosion reaction mechanism. Results reveal that during the corrosion process, the CFAS melt infiltrates Lu₄Hf₃O₁₂ particles through cracks, resulting in the formation of a continuous reaction layer. This reaction leads to the generation of several high-melting-point garnets, including HfO₂, Lu₃Al₅O₁₂, Ca₃Fe₂(SiO₄)₃ (Ca-Fe garnet), and Ca₃Al₂Si₃O₁₂ (Grossular). These garnets effectively fill the voids within the Lu₄Hf₃O₁₂ ceramics, preventing further infiltration of the CFAS melts. As time progresses, the rate of the reaction gradually increases, while the rate of infiltration consistently decreases. Consequently, a relatively stable corrosion layer is achieved, effectively impeding further corrosion.