材料期刊网

为了提高变压器油的绝缘特性，选取直径为40 nm的AlN纳米粒子，制备出不同浓度的AlN纳米改性变压器油，通过透射电子显微镜对变压器油中纳米粒子的尺寸展开研究，并对不同浓度纳米改性变压器油的雷电冲击特性进行分析。结果表明：纳米改性变压器油中的纳米粒子直径主要分布在20~500 nm之间。随着纳米粒子浓度的上升，纳米变压器油的正极性雷电冲击击穿电压比纯净变压器油提升了约50%，并随着纳米粒子浓度的上升呈现先上升后下降的趋势。根据雷电冲击特性的实验结果，利用“势井模型”解释了纳米变压器油正极性雷电冲击击穿电压比纯净变压器油升高的原因，并提出随着纳米粒子浓度的升高，由纳米粒子数密度增加导致的总捕获电荷数量增加和纳米粒子等效半径增加导致的总捕获电荷数量减少是一对竞争关系的理论，从而解释了纳米变压器油的正极性雷电冲击击穿电压先升高后下降的原因。

In order to improve the insulating properties of transformer oil, transformer oil nanofluids with different concentrations were prepared from AlN nanoparticles with 40 nm of diameter. The size of AlN particles was investigated via transmission electron microscope (TEM), and the lightning impulse character-istics of the transformer oil nanofluids were analyzed. The results show that the diameter of AlN nanopar-ticles in the transformer oil ranges from 20 nm to 500 nm. It is found that the positive lightning impulse breakdown voltage of transformer oil nanofluids increases by about 50% compared to the pure transformer oil, and the positive lightning impulse breakdown voltage increases at first and then decrease with the increase of the concentration of nanoparticles. The“potential well model”is used to explain the reason why the positive lightning impulse breakdown voltage increases. It is proposed that there is a com-petitive relationship between the increase of nanoparticle number leading to the increase of charge quantity and the increase of nanoparticle radius leading to the decrease of charge quantity, which explain the phenomenon that the positive lightning impulse breakdown voltage increase at first and then decrease.