Abstract

The paper reports on the thermodynamic analysis of the CaO–Y₂O₃–ZrO₂–Ti–Fe₂O₃ system as a precursor for SHS-produced pyrochlore-based ceramics. Adiabatic combustion temperature T_ad and equilibrium concentration of pyrochlore were first calculated for the quasi-ternary system Y₂O₃–ZrO₂–(Ti + Fe₂O₃) containing no CaO. It was found that, in the presence of CaO, a best yield of Zr-enriched pyrochlore ceramic can be reached within the following domain of green compositions (wt %): CaO 2.5–5.0, Y₂O₃ 22.5–35.0, ZrO₂ 7.5–22.5, and (40% Ti + 60% Fe₂O₃) 45.0–60.0; within this domain, T_ad = 2100–2400°K. Although in control experiments T_ad was found to be within the range 1700–1970 K, nevertheless the combustion products always showed the presence of pyrochlore-based ceramic, as predicted by thermodynamic analysis.

中文翻译：

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CaO–Y 2 O 3 –ZrO 2 –Ti–Fe 2 O 3系统作为前驱体用于SHS生产的烧绿石基陶瓷的热力学分析

摘要

本文报道了作为SHS生产的烧绿石基陶瓷前体的CaO–Y ₂ O ₃ –ZrO ₂ –Ti–Fe ₂ O ₃系统的热力学分析。首先计算不含CaO的准三元体系Y ₂ O ₃ -ZrO _2-（Ti + Fe ₂ O ₃）的绝热燃烧温度T _ad和烧绿石的平衡浓度。发现在存在CaO的情况下，可以在以下绿色组成（wt％）范围内达到最佳的富Zr烧绿石陶瓷的最佳产量：CaO 2.5–5.0，Y ₂ O ₃22.5-35.0，ZrO ₂ 7.5-22.5和（40％Ti + 60％Fe ₂ O ₃）45.0-60.0；在这个范围内，T _ad = 2100–2400°K。尽管在对照实验中发现T _ad在1700–1970 K范围内，但是燃烧产物始终显示出以热解氯为基础的陶瓷，如热力学分析所预测的那样。