Rare-earth (RE) hafnates are promising thermal and environmental barrier coating (TEBC) materials for SiC_f/SiC ceramic matrix composites. In this study, pure-phase and dense δ-RE₄Hf₃O₁₂ (RE = Yb, Lu) bulk ceramics have been fabricated via a hot-pressing method. The crystal structure, microstructure, mechanical, and thermal properties of δ-RE₄Hf₃O₁₂ were systematically investigated in order to probe their potential application as TEBCs. The high-temperature elastic moduli of δ-Yb₄Hf₃O₁₂ and δ-Lu₄Hf₃O₁₂ are measured to be 185 and 188 GPa at 1673 K, respectively, which are over 85% values of room temperature. The coefficients of thermal expansion are 7.64 × 10⁻⁶ and 7.46 × 10⁻⁶ K⁻¹ for δ-Yb₄Hf₃O₁₂ and δ-Lu₄Hf₃O₁₂, respectively. The relatively low coefficient of thermal expansion and thermal conductivity as well as their excellent high-temperature stability endow these hafnates as potential TEBC candidates.

中文翻译：

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δ-RE4Hf3O12 (RE = Yb, Lu) 的机械和热性能

稀土 (RE) 铪酸盐是用于 SiC _f /SiC 陶瓷基复合材料的有前途的热和环境屏障涂层 (TEBC) 材料。在本研究中，采用热压法制备了纯相致密 δ-RE ₄ Hf ₃ O _{12 (RE = Yb, Lu) 块状陶瓷。系统地研究了 δ-RE 4} Hf ₃ O ₁₂的晶体结构、微观结构、机械和热性能，以探讨它们作为 TEBC 的潜在应用。_{δ-Yb 4} Hf ₃ O ₁₂和δ-Lu ₄ Hf ₃ O ₁₂的高温弹性模量在 1673 K 时的测量值分别为 185 和 188 GPa，超过室温值的 85%。δ-Yb ₄ Hf ₃ O ₁₂和δ-Lu ₄ Hf ₃ O ₁₂的热膨胀系数分别为7.64×10 ^-6和7.46×10 ^-6  K ^-1。相对较低的热膨胀系数和导热系数以及出色的高温稳定性使这些铪酸盐成为潜在的 TEBC 候选材料。