Al_2O_3/BaZrO_3双陶瓷界面微观组织演化及机理

Microstructure Evolution and Mechanism of Al_2O_3/BaZrO_3 Double Ceramics

以Al_2O_3为背层(硅溶胶为粘结剂),电熔BaZrO_3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Al_2O_3/BaZrO_3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BaZrO_3层和Al_2O_3/BaZrO_3界面的显微结构,研究了BaZrO_3与Al_2O_3的界面反应。结果表明,面层由BaZrO_3基体和分布其上的大小10μm左右的Y稳定的ZrO_2晶粒组成;Al_2O_3/BaZrO_3界面发生反应形成厚约300μm的过渡层,界面反应生成物有BaO Al_2O_3、ZrO_2和Ba O Al_2O_32SiO_2。界面从单纯的BaZrO_3/Al_2O_3双陶瓷结构演变为BaZrO_3、ZrO_2、BaOAl_2O_3、BaOAl_2O_32SiO_2和Al_2O_3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,BaZrO_3中Ba元素向Al_2O_3所在的位置扩散形成Ba O Al_2O_3,残留物形成一层条状ZrO_2,而BaOAl_2O_32SiO_2围绕着EC95(Al_2O_3+5%SiO_2)粉体颗粒周围生成。

The A1203/BaZrO3 double ceramics sample with size of 50 mmx25 ramx5 mm was prepared via sintering at 1550℃ by using A1203 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 grn） uniformly distributed. The interface reaction between A1203 and BaZrO3, leads to form a 300 gm thick transition layer. Composed of BaA1204 （BaO＇A1203） and ZrO2. Thus, the microstructure of interface transfers from a simple double ceramic A1203/BaZrO3 interface into a complex structure, which is composed of BaZrO3, ZrO2, BaO＇A1203, and A1203. During the reaction, the element Ba of BaZrO3 migratesinto the A1203 layer and forms BaO＇A1203, then the residual becomes a strip-shaped ZrO2 layer. The element A1 of A1203 almost does not diffuse, and the ternary oxides BaO＇A1203＂2SiO2 are formed around EC95（A1203＋5%SiO2） particles.