Balancing sintering and thermal shock resistance of Y2O3 ceramics: The dual role of Ca(OH)2 and Zr(OH)4

The effect of Ca(OH) 2 and Zr(OH) 4 on the sintering behavior and thermal shock resistance of Y 2 O 3 ceramics were investigated in this study. The results showed that Ca(OH) 2 enhanced the densification of Y 2 O 3 ceramics. CaO generated from the decomposition of Ca(OH) 2 reacted with Y 2 O 3 to form a solid solution. The substitution of Ca 2 + for Y 3+ created V O ∙ ∙ that facilitated substance migration and pore elimination. Conversely, the introduction of Zr(OH) 4 exerted an adverse effect on the sintering. ZrO 2 produced by the decomposition of Zr(OH) 4 formed a solid solution with Y 2 O 3 which inhibited the sintering of Y 2 O 3 ceramics, where Zr 4+ primarily enhanced lattice stability rather than promoting sintering. The O i ′ ′ created by the substitution of Zr 4+ for Y 3+ reduced cation diffusion and hindered grain boundary migration. The mechanisms by which two types of additives affect the thermal shock stability of Y 2 O 3 ceramics are different. The Zr(OH) 4 -doped ceramics demonstrated better thermal shock resistance owing to their higher porosity, which changed energy release pathway and increased the resistance to crack propagation. In comparison, the improvement in the Ca(OH) 2 -doped ceramics mainly originated from the enhanced mechanical properties, which would suppressed crack initiation and delayed failure under thermal stress.