Al2O3/BaZrO3双陶瓷界面微观组织演化及机理

以Al₂O₃为背层(硅溶胶为粘结剂), 电熔BaZrO₃作为面层材料(钇溶胶为粘结剂), 1550℃烧结后制成50 mm×25 mm×5 mm的Al₂O₃/BaZrO₃双陶瓷试样。通过光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)和EDS等手段观察了BaZrO₃层和Al₂O₃/BaZrO₃界面的显微结构, 研究了BaZrO₃与Al₂O₃的界面反应。结果表明, 面层由BaZrO₃基体和分布其上的大小10 μm左右的Y稳定的ZrO₂晶粒组成; Al₂O₃/BaZrO₃界面发生反应形成厚约300 μm的过渡层, 界面反应生成物有BaOAl₂O₃、ZrO₂和BaO·Al₂O₃·2SiO₂。界面从单纯的BaZrO₃/Al₂O₃双陶瓷结构演变为BaZrO₃、ZrO₂、BaO·Al₂O₃、BaO·Al₂O₃·2SiO₂和Al₂O₃等多种物相组成的复杂结构。反应过程中Al元素基本不迁移扩散, BaZrO₃中Ba元素向Al₂O₃所在的位置扩散形成BaO·Al₂O₃, 残留物形成一层条状ZrO₂, 而BaO·Al₂O₃·2SiO₂围绕着EC95(Al₂O₃+5%SiO₂)粉体颗粒周围生成。

Microstructure Evolution and Mechanism of Al2O3/BaZrO3 Double Ceramics

The Al₂O₃/BaZrO₃ double ceramics sample with size of 50 mm×25 mm×5 mm was prepared via sintering at 1550℃ by using Al₂O₃ as back layer (silica sol as binder), fused BaZrO₃ as surface ceramics. The phase identification and crystal structure were determined by X-ray diffraction (XRD), while the microstructure and interfacial reaction were carried out by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscope (EDS). SEM-EDS results show that the surface layer is mainly composed of BaZrO₃ matrix, with tiny yttria-stabilized zirconia grains (10 μm) uniformly distributed. The interface reaction between Al₂O₃ and BaZrO₃, leads to form a 300 μm thick transition layer. Composed of BaAl₂O₄ (BaO·Al₂O₃) and ZrO₂. Thus, the microstructure of interface transfers from a simple double ceramic Al₂O₃/BaZrO₃ interface into a complex structure, which is composed of BaZrO₃, ZrO₂, BaO·Al₂O₃, and Al₂O₃. During the reaction, the element Ba of BaZrO₃ migrates into the Al₂O₃ layer and forms BaO·Al₂O₃, then the residual becomes a strip-shaped ZrO₂ layer. The element Al of Al₂O₃ almost does not diffuse, and the ternary oxides BaO·Al₂O₃·2SiO₂ are formed around EC95(Al₂O₃+5%SiO₂) particles.