提高ZnO压敏电阻片电位梯度的研究

为了进一步提高ZnO压敏电阻片的电位梯度和能量耐受能力,研究了添加剂复合粉体的颗粒度、烧结温度和保温时间对电阻片电位梯度和能量耐受能力的影响。采用细度为(0.4～0.6)μm的添加剂,在1 120℃保温5h,φ56mm的电阻片电位梯度可达(3.2～3.5)kV/cm;在传统添加剂细度的基础上,烧结温度为1 200℃,保温5h可获得梯度为(1.7～1.8)kV/cm,方波为800A的大容量电阻片。从传统电位梯度和高梯度电阻片显微结构分析中得出,晶粒细小化是提高电位梯度的重要途径。尖晶石是晶粒生长的钉扎中心,可以抑制晶粒过分长大,控制尖晶石的颗粒大小、均匀分布是控制和促使ZnO晶粒均匀细小化的关键。

Study on Enhancement of Electric Gradient of ZnO Varistor for HV Surge Arrester

In order to better meeting the requirements of metal oxide surge arrester for high reliability,lightweight and small size the essential topic is enhancement of electric stress and energy withstand capacity of ZnO varistor.The effect of grain size of additive synthetics,sintering temperature and its maintaining duration on enhancement of electric gradient and discharge capacity of varistor were described.Fine dispersion of additive synthetics 0.4 μm～0.6 μm,appropriate sintering temperature(e.g.1 120 ℃)1and sufficient maintaining duration(e.g.5 h) may lead to produce varistor of serious electric gradient and discharge capacity.The varistor of 56 mm may have electric gradient up to 3.2 kV/cm ～3.5kV/cm,with traditional additive finess and sintering temperature of 1 200 ℃ and maintaining duration of 5 h,a varistor having electric gradient of 1.7 kV/cm～1.8 kV/cm and rectangular long duration surge discharge withstand capability up to 800 A can be obtained.As seen from convenient microstructure of varistor with high gradient and discharge capacity the essential way to enhance electric gradient is crystal miniaturization.Since the spinel is the pin centre of crystal growth activating suppression of excessive crystal growth,so controlling the spinel size and dispersion is the key point for facilitating fine dispersion of ZnO particles.