The high-temperature (1500 °C) interactions of two promising dense, polycrystalline EBC ceramics, YAlO₃ (YAP) and γ-Y₂Si₂O₇, with a calcia-magnesia-aluminosilicate (CMAS) glass have been explored as part of a model study. Despite the fact that the optical basicities of both the EBC ceramics and the CMAS are similar, they both react with the CMAS. In the case of the Si-free YAlO₃, the reaction zone is small and it comprises three regions of reaction-crystallization products, including Y-Ca-Si apatite solid-solution (ss) and Y₃Al₅O₁₂ (YAG)(ss). In contrast, only Y-Ca-Si apatite(ss) forms in the case of Si-containing γ-Y₂Si₂O₇, and the reaction zone is an order-of-magnitude thicker. These CMAS interactions are analyzed in detail, and are found to be strikingly different than those observed in Y-free EBC ceramics (β-Yb₂Si₂O₇ and β-Sc₂Si₂O₇) in the accompanying Part II paper. This is attributed to the presence of the Y in the YAlO₃ and γ-Y₂Si₂O₇ EBC ceramics.

高温（1500℃）的2相互作用有前途的致密的，多晶EBC陶瓷，YALO ₃（YAP）和γ-Y ₂的Si ₂ ö ₇，具有氧化钙-氧化镁-铝硅酸盐（CMAS）玻璃已探索作为部分模型研究 尽管EBC陶瓷和CMAS的光学基础相似，但它们都与CMAS发生反应。在无硅的YAlO ₃的情况下，反应区很小，并且包括三个反应结晶产物区域，包括Y-Ca-Si磷灰石固溶体（ss）和Y ₃ Al ₅ O ₁₂（YAG） （ss）。相比之下，只有Y-Ca-Si磷灰石（SS -含有Si）中的情况下，形式γ-Y ₂的Si ₂ ö ₇，和反应区是为了数量级的更厚。这些CMAS相互作用进行了详细分析，并且被认为是比在Y型自由观察到显着不同的EBC陶瓷（β-镱₂的Si ₂ ö ₇和β-Sc合金₂的Si ₂ ö ₇）在所附的第二部分的纸张。这归因于在Y在YALO存在₃和γ-Y ₂的Si ₂ ö ₇ EBC陶瓷。