特快波前下金属氧化物电阻片伏安特性试验研究

设计搭建了模拟特快速瞬态过电压发生器，并确定了相关的电压、电流测量方法，选定具有代表性的超高压避雷器使用的金属氧化物电阻片（MOV）作为研究对象，试验研究了MOV在电流波头时间为80～150ns的特快波前冲击电流下的伏安特性、电流陡度的影响关系及阻抗特性。在特快波前冲击电流作用下，MOV伏安特性试验结果表明：随着电流波头时间的减小，MOV的电压峰值升高，MOV电压峰值远大于同电流标准雷电波下的电压峰值，特快波前电流冲击波下MOV残压上升约9％～16％；MOV的电压峰值随着电流峰值的增大而增大，而且电流波头时间越短，同一电流值下的电压峰值越高，在特快波前冲击电流波头时间由150ns变化至80ns时，MOV电压峰值上升约为10％～20％；在试验研究的电流波头时间范围和电流峰值范围内，电压峰值出现的时间明显超前于电流峰值出现的时间，呈现感性阻抗特征。

Sintering effect on electrical properties and pulse aging behavior of(V_2O_5-Mn_3O_4-Er_2O_3 )-doped zinc oxide varistor ceramics

The effect of sintering temperature on microstructure, electrical properties, and pulse aging behavior of （V2O5-Mn3O4-Er2O3）-doped zinc oxide varistor ceramics was systematically studied. When the sintering temperature increased, the average grain size increased from 6.1 to 8.7μm and the sintered density decreased from 5.52 to 5.43 g/cm3. The breakdown field decreased from 3856 to 922 V/cm with an increase in the sintering temperature up to 900 °C, whereas a further increase to 2352 V/cm at 925 °C. The nonlinear coefficient increased pronouncedly from 4.6 to 30.0 with an increase in the sintering temperature. The varistor ceramics sintered at 850 °C exhibited the best clamping characteristics, with the clamp voltage ratio of the range of 2.22-2.88 for pulse current of 1-25 A. The varistor ceramics sintered at 925 °C exhibited the strongest stability, with %ΔE1 mA/cm2=-8.8% after applying the multi-pulse current of 25 A.

Microstructure, electrical and dielectric properties, and aging behavior of ZPCCA varistor ceramics with Er_2O_3 doping

The microstructure, electrical and dielectric properties, and DC-accelerated aging of the ZPCCA （ZnO-Pr6O11-CoO- Cr203-A1203） ceramics were investigated with various contents of Er203. The ceramic phases consisted of a bulk phase of ZnO grains, and a minor secondary phase of mixture of Pr6O11 and Er203. The increase of the content of doped Er203 increased the densities of sintered pellet from 5.66 to 5.85 g/cm3, and decreased the average grain size from 9.6 to 6.3 μm. With the increase of the content of doped Er203, the breakdown field increased from 2390 to 4530 V/cm, and the nonlinear coefficient increased from 28.4 to 39.1. The sample doped with 0.25 mol.% Er203 exhibited the strongest electrical stability; variation rates for the breakdown field measured at 1.0 mA/cm2, and for the non-ohmic coefficient were -3.4% and -23,8%, respectively, after application of a stress of 0.95 Eu/125 ℃/24 h.

三氧化钨陶瓷的压敏特性和机理

采用传统电子陶瓷烧结工艺,制备了无掺杂物的三氧化钨(WO3)陶瓷。分析了陶瓷样品经淬火和不同气氛下处理后的微结构和压敏电学特性。研究表明:陶瓷冷却过程中在氧吸附的作用下,WO3陶瓷晶粒表面呈现氧元素富集。分析认为,晶粒表面吸附的氧与晶粒内的电子作用,在晶粒表面形成界面态,并进一步在晶界形成Schottky势垒,这可能是WO3陶瓷压敏行为的起源。根据实验结果,提出了一种修正的晶界Schottky势垒模型,解释了WO3陶瓷的压敏行为。