中频变压器用环氧树脂/纳米BN复合介质的导热和电气性能研究

Study on thermal conductivity and electrical properties of epoxy resin/nano BN composites in medium frequency transformers

为了研究中频变压器用环氧树脂复合材料的导热和电气特性,本文选取高导热纳米氮化硼(BN)颗粒作为填料,利用盐酸多巴胺对其进行表面修饰,采用溶液法制备了环氧树脂/纳米BN复合材料试样(BN质量分数分别为1%、2%和5%),通过扫描电子显微镜对试样的微观形貌进行分析,测试了试样的热导率、体积电导率、中频击穿场强和表面电位衰减特性。结果表明:纳米BN的添加提高了环氧树脂的热导率;1 wt%和2 wt%纳米BN的添加降低了环氧树脂的电导率和载流子迁移率;随着电压频率的升高,试样的击穿场强降低;随着纳米BN浓度的增加,击穿场强呈现出先升高后降低的趋势;纳米BN能够缓解环氧树脂击穿场强随频率升高的影响,降低环氧树脂的表面电位衰减速度。上述结果表明,适量添加1 wt%和2 wt%的纳米BN能够提高中频变压器用环氧树脂复合材料的导热和电气性能。

To study the thermal conductivity and electrical properties of epoxy resin(EP)composites in medium frequency transformers,nano-boron nitride(BN)with high thermal conductivity is selected as filler to add into EP.EP/nano-BN composite samples with mass content 0%,1%2%and 5%of nano BN which has been surfaced-treated by dopamine hydrochloride are prepared by solution blending.The micro-morphology of samples is analyzed by scanning electron microscope.Thermal conductivity,DC volume conductivity,medium frequency breakdown strength and surface potential decay characteristics of the samples are studied.The results show that the thermal conductivity of EP increases by adding nano BN;the volume conductivity and carrier mobility of EP decrease with the addition of 1 wt%and 2 wt%nano BN;the breakdown strength of samples drops with frequency increasing;with the increase of nano BN concentration,the breakdown strength increases first and then decreases;the effect of breakdown strength with frequency increasing can be alleviated,and the surface potential decay of EP can be slowed down by adding nano BN.In conclusion,the thermal conductivity and electrical properties of EP composites in medium frequency transformers can be improved by adding 1 wt%and 2 wt%nano BN.