高频电场对高温硫化硅橡胶介电性能的影响

Influence of High Frequency Electric Field on Dielectric Performance of High Temperature Vulcanizing Silicone Rubber

为了研究复合绝缘子硅橡胶在高频电场下的老化机理,文中搭建了高频电老化试验平台,研究了高频电场对高温硫化硅橡胶老化后微观性能的影响,结果表明:高频电老化使硅橡胶表面出现孔洞和大量裂纹,部分填料分解、流失,羟基含量先降后增,但最终仍低于未老化试样,造成界面静态介电极化率降低,削弱了界面极化强度;热解第3阶段失重量随电老化时间增加,说明PDMS分子长链断裂,极性基团数目增加,偶极子极化率和极化强度增大;此外,硅橡胶介电常数和介电损耗随老化时间增大,并在144 h出现明显的介质损耗峰。通过修正Cole-Cole模型,将介电频谱曲线划分为3个驰豫过程和2个电导过程,其变化规律在SEM分析、红外光谱分析和TG分析中得到印证,并提出可用来定量评估硅橡胶高频电老化状态的参量—偶极子静态介电极化率。文中提出了一种新的人工加速老化方法,并探讨了其介电性能的变化趋势,从中提取新的老化状态评估参量,可为进一步探索高频电老化机理和老化效率提供理论参考。

For studying the aging mechanism of silicone rubber of composite insulator under high frequency electric field,the high frequency electric aging test platform is set up in this paper so to study the influence of high frequency electric field on the micro properties of high temperature vulcanized(HTV)silicone rubber after aging.The results show that:High⁃frequency electrical aging causes holes and a large number of cracks on the surface of silicone rub⁃ber,and some fillers decompose and lose and the hydroxyl content decreases first and then increases,but it is eventu⁃ally still lower than that of the unaged sample,causing the decrease of the static dielectric polarization of the interface and weakening the interface polarization strength.The weight loss at the third stage of pyrolysis increases with the electric aging time,which indicates the breakage of long chain of PDMS molecules,increase of the number of polar groups and the increase of the polarization rate and strength of dipole.In addition,both the dielectric constant and di⁃electric loss of silicone rubber increase with the aging time and an obvious dielectric loss peak appears at 144 h.By modifying Cole-Cole model,the dielectric spectrum curve is divided into three relaxation processes and two conduc⁃tance processes,the variation rule is verified in SEM analysis,infrared spectrum analysis and TG analysis.The static dielectric polarization of dipole which can be used to quantitatively evaluate the high frequency electrical aging state of silicone rubber is proposed.In this paper,a kind of new artificial accelerated aging method is proposed and the vari⁃ation trend of its dielectric properties is discussed,from which the new aging state evaluation parameters are extract⁃ed,which can provide theoretical reference for further exploration of the mechanism and aging efficiency of high fre⁃quency electrical aging.