氧化锌非线性电阻片用无机高阻层的研究

Study of Inorganic Insulating Coating for Znic Oxide Varistor

研究了氧化锌非线性电阻片侧面用无机高阻层在4/10大电流冲击和2ms方波电流冲击作用下的破坏机理。认为影响电阻片耐受大电流冲击能力的关键之一是无机高阻层本身的绝缘强度,之二是无机高阻层和电阻片之间膨胀系数的配合问题,并通过试验指出,侧面绝缘层的膨胀系数应比ZnO陶瓷小0.5×10-6/℃～1.5×10-6/℃。影响电阻片耐受方波电流冲击能力的关键是无机高阻层和电阻片本体反应后所形成的中间层的稳定性。研制的无机高阻层可满足φ32mm×35mm、梯度为240V/mm的电阻片65kA大电流冲击的要求,并可提高电阻片的方波通流能力。

A study on destruction mechanism of inorganic lateral insulating coating for znic oxide varistor at high current and rectangular current surges is made. It is considered that first key aspect for heightening the high current surge withstand capacity is the dielectric strength of inorganic insulating coating, and the second aspect is coordination of thermal expansion coefficients between inorganic insulating coating and varistor body, which shall be 0.5×10^-6/℃-1.5×10^-6/℃ smaller than that of ZnO ceramics. The major aspect effecting rectangular surge withstand capacity is stability of intermediate layer formed at reaction of inorganic coating with ZnO resistor body. Using the newly developed inorganic high-resistive coating, a resistor of φ32 mm×35 mm with voltage gradient of 240 V/mm and high current withstand capacity of 65 kA is obtained, having meanwhile a enhanced long duration rectangular surge withstand capacity.