复合绝缘子密封胶老化因素研究

Study on ageing factors of composite insulator sealant

密封胶老化后水分会从密封胶界面侵入压接界面,引发绝缘子老化。为探究各老化因素对密封胶金具界面试样的作用机理,对密封胶开展了常温下28 d去离子水、盐溶液、硝酸溶液、硫酸溶液的浸泡试验以及不同温度下硝酸或硫酸与盐的混合溶液的浸泡试验,随后利用傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和能量色散谱仪(EDS)对试样的老化情况进行分析。结果表明:硫酸溶液对密封胶的硅氧烷基体作用不明显,盐溶液会造成硅氧烷侧链甲基断链,硝酸溶液会在硅氧烷侧链氧化生成-OH;常温下硝酸与盐的混合溶液对密封胶的影响大于高温情况,硝酸与盐的混合溶液对硅氧烷基体的作用基本等同于两种溶液单独作用的叠加。高温情况下硫酸与盐的混合溶液对密封胶的影响大于常温情况,硫酸与盐的混合溶液对硅氧烷基体的作用机理主要为:盐溶液使得硅氧烷侧链甲基断链,导致Si-O-Si主链暴露在硫酸中并发生断链,然后盐溶液又可以继续影响较深处的甲基基团。

After the ageing of sealant,the moisture will invade the crimping interface from the sealant interface,leading to insulator ageing.To investigate the affecting mechanism of various ageing factors on the interface samples between sealant and armour clamp,immersion tests were conducted on the sealant samples in deionized water,salt solution,nitric acid solution,sulfuric acid solution at room temperature for 28 days,as well as immersion tests in mixed solutions of sulfuric acid or nitric acid with salt at different temperatures.Then the ageing situation of the samples was analyzed by Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)scanning electron microscope(SEM),and energy dispersive spectrometer(EDS).The results show that the sulfuric acid solution has no significant effect on the siloxane matrix of sealant,while the salt solution can cause the breakage of methyl chain of the siloxane side chain,and the nitric acid solution can oxidize the siloxane side chain to generate-OH.The influence of nitric acid and salt mixed solution on the siloxane matrix at room temperature is greater than that at high temperature,and the effect of nitric acid and salt mixed solution on the siloxane matrix is basically equivalent to the superposition of the two solutions acting separately.The influence of sulfuric acid and salt mixed solution on the sealant at high temperature is greater than that at room temperature.The main affecting mechanism of sulfuric acid and salt mixed solution on the siloxane matrix is that the salt solution causes the methyl of silicone side chain to break,making the Si-O-Si main chain expose to sulfuric acid and undergo chain breaking,then the salt solution can continue to affect the deeper methyl groups.