用红外光谱研究室温硫化硅橡胶电晕老化及寿命估计

电晕是引起室温硫化硅橡胶(RTV)老化的重要因素之一,因此对RTV进行了电晕老化试验,并利用傅立叶变换红外光谱(FTIR)分析了RTV的电晕老化性能,比较了不同材料RTV的电晕老化性能,试验结果表明,纳米材料可以明显改善RTV的电晕老化性能。还分析了纳米材料提高RTV抗电晕性的机理,利用基于陷阱理论的聚合物电老化寿命公式及电晕老化前后材料的红外光谱变化评估了RTV的寿命,纳米材料能使RTV的电晕老化寿命提高到3～4.9倍。此方法可为定量评估有机绝缘材料寿命提供参考。     

RTV硅橡胶/层状硅酸盐纳米绝缘的力学性能

通过溶液插层法用纳米层状硅酸盐对 RTV硅橡胶电绝缘材料纳米改性并借助 XRD、SEM和 FT-IR等测试手段 ,研究了硅酸盐片层在 RTV硅橡胶中的分散性及其力学性能。试验表明纳米层状硅酸盐能在 RTV硅橡胶中较均匀地分散 ,所得 RTV/层状硅酸盐纳米复合体力学性能比纯 RTV硅橡胶更优异 ,耐漏电起痕能力也有所提高     

基于斜面法试验研究SiO_2质量分数对RTV硅橡胶涂料性能的影响

针对室温硫化(roomtemperature vulcanization,RTV)硅橡胶涂料应用中存在的黏附力不强、涂层易划破的问题,提出通过添加二氧化硅来提高硅橡胶的机械强度,改善材料的耐电痕化和耐电蚀损性。为此,结合热导率的概念,通过斜面法试验讨论了二氧化硅对RTV硅橡胶性能的影响,试验中采用西安交通大学电力电子专用设备研究所研制的高精度交流漏电起痕试验装置配合自行研发的多路泄漏电流实时监测采集装置,对制备的3种RTV硅橡胶涂料试片(只添加二氧化硅,且二氧化硅质量分数为20%、30%、50%)按照GB/T6553—2003《评定在严酷环境条件下使用的电气绝缘材料耐电痕化和蚀损的试验方法》进行试验。结论为:二氧化硅质量分数越高的硅橡胶热导率越大,热量越容易传导,耐电痕化和耐电弧烧蚀性越强;二氧化硅含量高、热导率大的硅橡胶试片到达过流保护动作的临界状态时,其烧蚀区域面积和烧蚀深度都较低二氧化硅含量的试片大;二氧化硅填料的增加使硅橡胶电蚀损后憎水性恢复过程减慢。     

电力设备防污闪复合纳米RTV涂料的研制

将纳米技术应用于RTV防污闪材料中,研制出RTV纳米复合绝缘材料。试验表明,所研制的SW-I型RTV纳米防污闪材料保持了RTV涂料原有的良好绝缘性、憎水性和憎水迁移性,在抗电老化、大气老化性能、机械强度、自洁性等方面均比普通RTV涂料大大提高,且可以显著提高绝缘子的耐污闪能力,是电力系统防污闪的理想材料。     

液体硅橡胶伞裙电蚀损修复方法及修复后性能研究

为修复液体硅橡胶伞裙表面的电蚀损坑洞,提出了一种采用室温硫化硅橡胶(RTV)修补胶和RTV防污闪涂料联合修补的方法。采用人工涂污的方法,模拟硅橡胶伞裙表面电蚀损的现象,使用RTV防污闪涂料和修补胶填补电蚀损坑洞,并对比修复前后的硬度、憎水性、耐电痕化和电蚀损性能。结果表明:修复后液体硅橡胶的性能与电蚀损前的水平相当。通过附着力测试和SEM观察发现,液体硅橡胶和RTV界面粘接良好。说明该修复方法可以用于修复液体硅橡胶表面电蚀损形成的坑洞,使其绝缘性能得到恢复。     

高压绝缘防污闪涂层的研究进展

室温硫化(RTV)硅橡胶以其独特的憎水性和憎水迁移性而被用作新型高压绝缘防污闪材料,但仍存在附着力差,强度弱,阻燃性差等缺陷。为提高RTV硅胶的防污闪作用,进一步开展相关的研究工作,综述了污闪产生的机制,RTV硅胶的组成及特点、研究与应用。在概述了国内外RTV硅胶研究近况和RTV硅胶的小分子憎水迁移机理后阐明了纳米技术有效提高RTV硅胶的机械性能和耐老化性能,阻燃剂(如氢氧化铝)改善RTV硅胶的耐漏电起痕性、阻燃性能等的效果。最后指出,进一步提高RTV硅胶的机械性能、电气性能、抗老化性能是今后研究工作的热点。     

有机绝缘材料耐电痕化的影响因素探讨

综述了有机绝缘材料的电痕化性能,分析了电痕化的过程、影响因素,提出了改善材料抗电痕化能力的方法。     

紫外辐射对室温硫化硅橡胶性能的影响

选择目前市场上使用量较大的4种室温硫化硅橡胶(RTV)涂料,分别涂覆在瓷片表面制成试品,进行紫外加速老化试验,在老化过程中对其静态接触角、傅里叶红外光谱、表面微观形貌、耐漏电起痕与蚀损能力进行测量。结果表明:随着紫外辐射时间的增加,RTV试品的静态接触角总体呈先增大后减小的趋势,在紫外辐射400～766 h后,相当于实际太阳光照射4.2～8.0年,4种样品的静态接触角均不符合电力标准DL/T627—2012要求;紫外老化后,RTV的甲基、羟基含量明显降低,RTV表面粗糙度增大,表明在紫外老化过程中RTV发生了交联反应和氧化反应;紫外辐射前后,RTV的耐漏电起痕与蚀损能力变化不大,均能达到1A4.5级的要求。     

不同类型RTV憎水性及闪络特性分析

室温硫化硅橡胶（room temperature vulcanized silicone rubber,RTV）具有很好的防污性能,在电力系统中已广泛应用,但不同类型的RTV涂料防污性能不同。测定了不同RTV涂料的静态接触角,并对RTV涂料污闪后的憎水性恢复特性以及交直流下的闪络特性进行了试验分析。试验结果表明,长效型RTV涂料（P-RTV）的憎水性大于高自洁型RTV涂料（S-RTV）;在同一污秽度下P-RTV污闪电压比S-RTV高,说明更强的憎水性意味着更高的防污性能。此外,沿面闪络会导致P-RTV涂料憎水性暂时性的部分丧失,污闪电压幅值下降11.1%~21.1%,此部分丧失一段时间后可恢复,而S-RTV涂料憎水性的丧失部分却是不可恢复的;RTV涂料表面均有不同程度灼烧痕迹且放电痕迹分布在与高压端相连的绝缘子下表面,这是导致表面防污性能下降的因素之一。直流电压下RTV涂料表面灼烧痕迹明显,抗漏电起痕性能较弱。P-RTV综合性能优于S-RTV,因此实际使用应优先考虑P-RTV。研究结果对RTV涂料的研制和使用具有一定的指导意义。     

ADSS光缆耐电痕护套料的研究

描述了ADSS光缆护套料耐电痕性的原理，通过几种不同耐电痕护套料的物理、工艺及时电痕性能的比较与研究，选择出了优良的ADSS光缆用耐电痕护套料。     

Electrical performance of RTV silicone rubber coatings

The role played by two major constituents in a room temperature vulcanized (RTV) silicone rubber coating, namely, the inorganic alumina trihydrate (ATH) filler and the silicone polymer, on the coating's electrical performance was examined. The principal variable in the RTV silicone rubber coatings evaluated was the different weight fraction of the silicone polymer and ATH inorganic filler normally used for improving the tracking and erosion resistance. Other formulation details were essentially the same in the cured rubber. The coatings were spray coated on glazed porcelain rods and subjected to accelerated aging in a salt fog chamber. The changes produced by accelerated aging on the contamination withstand capability, leakage current suppression and erosion resistance were determined and correlated with the ratio of polymer to inorganic filler in the coating. It is shown that critical aspects of electrical performance necessary for satisfactory service operation such as contamination withstand capability before flashover and leakage current suppression are superior for the coating with a relatively high ratio of polymer to inorganic filler in comparison to the coatings with a relatively low ratio of polymer to inorganic filler. While all the coatings showed a high erosion resistance under mild discharge activity, the erosion resistance was found to be superior for the formulations with high inorganic filler under conditions of intensive surface discharge activity     

Role of the size of particles of alumina trihydrate filler on thelife of RTV silicone rubber coating

The paper reports on a study of the influence of the size of the particles of alumina trihydrate (ATH-Al₂O₃.3H₂O) filler on the life of room temperature vulcanised (RTV) silicone rubber coating in a salt-fog chamber. The particle sizes examined include 1.0, 4.5, 13, 17 and 75 μm. The optimum size to give the lowest leakage current and the longest time to failure of the coating is determined. The particle size affects the roughness of the coating. This is determined by a high resolution surface roughness tester and a scanning electron microscope (SEM) examination. The roughness is enhanced after prolonged testing in salt-fog. The leakage current affects the amount of silicone fluid on the surface. The amount of silicone fluid present on the surface after exposure to dry-band arcing in salt-fog is a function of the particle size. Measurements of surface roughness, the amount of silicone fluid on the surface and the leakage current combined with theoretical analysis of the heat of conduction lead to identification of the mechanisms by which the size of the ATH particle imparts resistance to tracking and erosion     

Low-molecular weight silicone fluid in RTV silicone rubber coatings

Coatings of room-temperature vulcanized (RTV) silicone rubber (SIR) are used increasingly on outdoor HV porcelain and glass insulators and bushings when subjected to heavy pollution. An important property of the RTV-SIR coating is its ability to restore the hydrophobicity of the surface after a layer of contamination has built up on it, and thus continue to suppress the development of leakage current, dry band arcing and flashover. This is accomplished by the diffusion of low molecular weight (LMW) silicone fluid from the bulk to the surface of the coating and then to the top of the contamination layer. The presence of sufficient LMW silicone fluid in the bulk of the coating is a critical factor in both the recovery of hydrophobicity and its long term maintenance under wet and polluted conditions. This paper reports on several factors which affect the level of LMW silicone fluid present in RTV-SIR coatings. Different formulations of the RTV-SIR were used. The percentage weight of the LMW silicone fluid was determined in RTV-SIR coatings as a function of the size of the particles of the alumina trihydrate (ATH) filler which was varied from 1 to 75 μm, the concentration of the ATH filler from 50 to 150 pph of the base silicone rubber, the addition of 10%wt silicone fluid to the formulation of RTV-SIR, the carrier solvents of 1,1,1 trichloroethane and naphtha, exposure to continuous wind at a speed of 7.45±0.25 km/h for 22 months, exposure to stationary air for 14 months, immersion in low salinity water simulating rain (70 μS/cm) for 14 months and tests in energized low conductivity salt-fog. The mechanisms responsible for the observed phenomena are suggested and discussed     

纳米TiO2改性室温固化硅橡胶的力学性能研究

为进一步提高RTVSR的各项性能,近年来虽有针对其各项性能的纳米粒子改性研究,但是从力学性能上的研究和成果并不多。介绍了用金红石型纳米级TiO2共混改性RTVSR,得到一种新型的耐老化和力学性能优良的防污闪绝缘复合涂料。通过研究复合材料的力学性能并与空白RTVSR进行对比,进一步采用FT-IR、XRD、SEM等先进仪器分析了纳米复合材料的化学结构,确定了当TiO2添加量为6%时,断裂伸长率达到了345%,拉伸强度为0.27 MPa。从复合材料的基本电气性能测试结果可知,通过纳米粒子改性的RTVSR依然保持了良好的绝缘和憎水性能。试验结果表明,改性后的复合涂料力学和憎水性能优异,且保持了良好的电气性能。     

Effects of nano- and micro-filler mixture on electrical insulation properties of epoxy based composites

This paper focuses on the electrical insulation properties of a newly prepared composite material by nano- and micro-filler mixture. Nano- and micro-filler mixture composites were made by dispersing nano-scale layered silicate fillers and micro-scale silica fillers in epoxy resin. To investigate the effects of nano- and micro-filler mixture, the thermal expansion coefficient and insulation breakdown properties by a needle-plate electrode method were measured for the filler mixture composite and the conventional filled epoxy. The filler mixture composite had almost the same thermal expansion coefficient as the conventional filled epoxy. In a continuous voltage rising test, the filler mixture composite had 7% higher insulation breakdown strength than the conventional filled epoxy. Moreover, under constant AC voltage (10 kV at 1 kHz), the filler mixture composite had an insulation breakdown time of more than 20,000 minutes whereas the conventional filled epoxy had a breakdown time of 830 minutes. Electron microscope observation showed that the area surrounded by dispersed micro-scale silica fillers were also filled with the nano-scale layered silicate fillers. Furthermore, the estimate of spacing between the fillers and the filler/epoxy interface area showed a more densely-packed structure of the filler mixture composite than the conventional filled epoxy. The morphological feature of the filler mixture composite seems to improve its insulation breakdown strength and time.     

Effects of saline-water flow rate and air speed on leakage currentin RTV coatings

Room temperature vulcanizing (RTV) silicone rubber is increasingly being used to coat porcelain and glass insulators in order to improve their electrical performance in the presence of pollution and moisture. A study of the dependence of leakage current, pulse current count and total charge flowing across the surface of RTV on the flow rate of the saline water and on the compressed air pressure used to create the salt-fog is reported. The fog was directed at the insulating rods either from one or two sides. The RTV was fabricated from polydimethylsiloxane polymer, a filler of alumina trihydrate (ATH), a polymerization catalyst and fumed silica reinforcer, all dispersed in 1,1,1-trichlomethane solvent. The saline water flow rate was varied in the range 0.4 to 2.0 l/min. The compressed air pressure at the input of the fog nozzles was varied from 0.20 to 0.63 MPa. The air speed at the surface of the insulating rods was found to depend linearly on the air pressure measured at the inlet to the nozzles and varied in the range 3 to 14 km/hr. The leakage current increased with increasing flow rate and increasing air speed. This is attributed to the increased loss of hydrophobicity with a larger quantity of saline fog and a larger impact velocities of fog droplets interacting with the surface of the RTV coating     

室温硫化硅橡胶涂料的改性研究

室温硫化硅橡胶涂料是一种新型防污、憎水、长效涂料,目前已在我国许多地区投入使用。但从目前推广的室温硫化硅橡胶涂料性能来看,涂料与资件的粘附力不够强,影响了涂料的使用效果,而且耐电弧能力也较差。章研究了改进温室硫化硅橡胶涂料机械性能和耐电弧能力的方法,尤其是其防污闪的主要特性－憎水迁移特性没有明显减弱。中还研究了室温硫化硅橡胶涂料的憎水迁移特性。     

Tracking and erosion of HTV silicone rubber and suppressionmechanism of ATH

Tracking and erosion of high temperature vulcanizing (HTV)-silicone rubber (SIR) and the suppression mechanism of alumina trihydrate (ATH) filler were investigated in the present study. The tracking and erosion resistance of HTV-SIR filled with 0 to 60%wt ATH was evaluated by employing an IEC 587 inclined plane (IP) tracking and erosion test, during which leakage current pulses on HTV-SIR were counted. Surface temperature distributions and the occurrences of thermal spots >400°C also were observed by means of an infrared thermovision study. We employed thermogravimetry (TG)-differential thermal analysis (DTA)-mass spectrometer (MS) to observe the thermal degradation of unfilled and filled HTV-SIR in both air and argon. The test results indicate that 40%wt is a critical ATH level and whether tracking and erosion is allowed in the IP tracking and erosion test. Highly filling ATH (>40%wt) reduces the number of low unit silicone oligomer precursors which promote dry-band arcing as well as the presence of residual carbon which leads to carbonization. Chemical modifications of water vapor liberated from heated ATH to methyl groups, which occurs at the thermal decomposition temperature of silicone rubber, were found to result in the above process. The protection mechanisms of ATH for the tracking and erosion of HTV-SIR are formulated herein