脉冲形成线用CaO-TiO2-Al2O3 基介质陶瓷介电性能

摘要

A new CaO-TiO2-Al2 O3 based dielectric ceramic system is designed for pulse forming line application.The die-lectric ceramic is prepared by traditional solid state method and its microstructure was controlled by optimizing the composition and preparation process.The dielectric ceramic exhibits an excellent dielectric properties.The frequency stability of the dielectric constant is good.The dielectric loss is less than 0.002 in a wide frequency range.The electric strength is up to 50 kV/mm (1 mm in thickness).The influence of thickness on the electric strength of CaO-TiO2-Al2 O3 based dielectric ceramics is studied.With the thickness decreasing from 1 mm to 0.1 mm,the dielectric breakdown strength increases nonlinearly from 50 kV/mm to 92 kV/mm.So it can be seen that the dielectric breakdown of the CaO-TiO2-Al2 O3 dielectric ceramics is similar to their mechanical damage.Based on the chemical compositions and the microstructures,the dielectric breakdown mechanism of CaO-TiO2-Al2 O3 dielectric ceramics can be explained by the weak breakdown theory.%设计了一种脉冲形成线用新型CaO-TiO2-Al2 O3 基介质陶瓷体系,采用传统固相法通过优化组分和制备工艺,调控材料的微结构,获得了介电性能优异的介质陶瓷.其介电常数在15~35 之间可调,介电损耗小于0.002,频率稳定性好.在厚度为1 mm时,介电强度高达50 kV/mm.研究了厚度对CaO-TiO2-Al2 O3基介质陶瓷介电强度的影响规律,当厚度从1 mm 减小到0.1 mm 时,介电强度呈非线性增大,从 50 kV/mm (1 mm厚样品)提高到92 kV/mm(0.1 mm厚样品),可见,CaO-TiO2-Al2 O3 基介质陶瓷的电击穿与其机械损坏具有相似性.结合CaO-TiO2-Al2 O3 基介质陶瓷的化学组分和微观结构,CaO-TiO2-Al2 O3 基介质陶瓷优越的电击穿特性可以用弱点击穿理论解释.