氧化锌压敏陶瓷击穿的几何效应与微观结构的关系

采用两面磨薄试样的方法，研究具有不同击穿场强的氧化锌压敏陶瓷的击穿场强与Ｅ１ｍＡ与厚度的关系，得到了击穿中场强Ｅ１ｍＡ随厚度变化的几何效应规律，利用光学显微方法，观测试样微观结构并用ＺｎＯ晶粒工度的分散度和平均晶粒长宽比作为微观结构特征参数表征ＺｎＯ晶粒尺寸分布的不均匀性和形状的不规整性，研究表明，临界厚度ｄ０与ＺｎＯ晶料尺寸的分散度成正比；斜率ｂ２与平均晶粒长宽比也成正比，建立了宏观电性能与微观

THE RELATION BETWEEN THE DIMENSIONAL EFFECT OF BREAKDOWN STRENGTH AND MICROSTRUCTURE IN ZnO VARISTOR CERAMICS

The relation between breakdown strength E 1mA and thickness of ZnO varistors with different breakdown strengths were experimentally investigated,and dimensional effect,i.e breakdown strength changing with thickness of samples,has been observed.The microstructures of samples were studied by means of optical micrographs.The dispersity of ZnO grain length and average length to width ratio of ZnO grains are used as characteristic values of microstructure to represent heterogeneity of ZnO grain size distribution and irregularity of ZnO grain shape.The critical thickness d 0 increases linearly with dispersity of ZnO grain length,and slope b 2 is directly proportional to average length to width of ZnO grains.The corresponding relation between electrical properties and characteristic values of microstructure has been established.