B2O3掺杂氧化锌压敏电阻烧结工艺的微观结构和电气特性

Microstructure and electrical characteristics of sintering process of B2O3 doped ZnO varistor

研究了在不同烧结温度下制备的直流ZnO压敏陶瓷的微观结构和电气特性。通过扫描电子显微镜,电流-电压的伏安特性,电容-电压和从小电流到大电流范围的X射线衍射图测量不同烧结温度下样品的电气参数和微观结构。实验结果表明在1150℃下烧结的样品晶粒尺寸比较均匀,非线性系数和泄漏电流分别为66和0.96μA/cm^2,电压梯度为381 V/mm,直流氧化锌压敏电阻的综合性能达到最优。随着烧结温度的升高,ZnO晶粒尺寸(d)会变大,导致单位长度内晶界数量减少使氧化锌压敏电阻的电压梯度减少。晶粒的尺寸的增加可以阻断三角区的互联互通,使泄漏电流减小。当烧结温度高于1150℃时,会造成Bi2O3的挥发使非线性系数降低。获得电压梯度为381 V/mm的直流氧化锌压敏电阻有利于优化超高压避雷器结构、电阻柱上的电位分布更加均匀。综上所述,制备B2O3掺杂的氧化锌压敏电阻配方最佳的烧结温度为1150℃。

In this paper,the microstructure and electrical properties of ZnO varistor ceramics were studied.The electrical parameters and microstructure of the samples at different sintering temperatures were measured by scanning electron microscopy,current-voltage voltammetry,capacitance-voltage and X-ray diffraction patterns from small current to large current.The experimental results show that the grain size of the sample sintered at 1150℃was relatively uniform,the nonlinear coefficient and leakage current were 66 and 0.96μA/cm^2,respectively,and the voltage gradient was 381 V/mm.The comprehensive performance of the DC zinc varistor reached the highest excellent.With the increase of sintering temperature,the grain size(d)of ZnO increased,which led to the decrease of grain boundary number per unit length and the decrease of voltage gradient of ZnO varistor.The increase in the size of the grains could block the interconnection and interconnection of the triangular area and reduce the leakage current.When the sintering temperature was higher than 1150℃,the volatilization of Bi2O3 would cause the nonlinear coefficient to decrease.The DC ZnO varistor with 381 V/mm voltage gradient could optimize the structure of ultra-high voltage arrester and make the potential distribution more uniform.In summary,the optimal sintering temperature for the preparation of B2O3 doped zinc oxide varistors was 1150℃.