Bi_2O_3-ZnO-Nb_2O_5(BZN)系低对称β相陶瓷的相转变与显微结构

PHASE TRANSITION AND MICROSTRUCTURE OF Bi_2O_3-ZnO-Nb_2O_5 (BZN)-BASED LOW SYMMETRY β PHASE CERAMICS

低对称 β相陶瓷是BZN系陶瓷的基本物相之一 .本工作以粉末XRD分析和断面SEM分析为研究手段 ,采用不同的冷却方式以及不同承烧垫板 ,研究了BZN系低对称 β相陶瓷在 110 0℃附近的熔融分解、转熔等相转变行为以及相应的显微结构变化 .研究表明 ,低对称 β相是异成分熔融化合物 ,在 110 0℃吸热分解为α相与液相 ;在自然冷却时 ,发生转熔过程 ,α相转入熔融液相中 ,析出 β相 ;在淬火冷却时 ,液相中析出BZN系立方萤石相 .对应于低对称 β相陶瓷在转熔温度 110 0℃附近的熔融分解、转熔等相转变行为 ,其显微结构也表现出相应的显著变化 .

Low symmetry β phase is one of the basic phases of BZN_based ceramics. In this paper, the phase transition and microstructure of β phase were explored under different conditions at about 1 100 ℃ with the help of XRD and SEM. The results show that BZN_based low symmetry β phase is an incongruent compound, dissociating to form α phase and liquid phase with absorption of heat, at peritectic temperature of 1 100 ℃. On cooling, the α phase reacts with liquid phase to form β phase by peritectic reaction. On quenching, BZN-based cubic fluorite phase precipitates from the liquid phase. The observable microstructure changes of phase correspond to the phase transition at about 1 100 ℃.