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。     

加成型液体硅橡胶耐电痕化及蚀损性能提升方法研究

加成型液体硅橡胶的耐电痕化及蚀损性能优化是外绝缘领域研究重点之一。该文分别改变气相法白炭黑质量分数及铂催化剂含量,制备A、B两个系列试样,采用斜面法测定各试样的耐电痕化性能,利用TG-FTIR-MS联用技术、扫描电镜,对比分析各试样的热分解产物、热稳定性及烧蚀面的微观形貌。结果显示,提高试样铂催化剂的含量及气相法白炭黑质量分数,均可提高试样的耐电痕化及蚀损性能,其中以前者效果更为显著。分析认为,环状二甲基硅氧烷低聚物分解生成是影响加成型液体硅橡胶耐电痕化及蚀损性能的重要因素;提高试样中气相法白炭黑质量分数,虽可以提高试样的热稳定性,但不足以抑制环状二甲基低聚物分解生成,以至于耐电痕化及蚀损性能提升效果有限;而将铂催化剂的含量从15ppm提高至30ppm后,硅氧烷的失重比例则由32.46%显著降至28.13%,试样的耐电痕化及蚀损性能等级则由1A2.5级提高至1A6.0级,表明提高铂催化剂的含量可抑制硅氧烷主链分解,从而大幅提升试样的耐电痕化及蚀损性能。     

RTV/纳米层状硅酸盐复合绝缘的抗电痕性

为提高RTV的抗电痕性,用纳米技术对其改性,合成RTV纳米复合材料并试验研究了它的耐漏电起痕及电蚀损能力,分析层状纳米材料的抗电痕机理的结果表明,层状纳米材料可大大提高RTV的抗电痕性。     

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。     

交流斜面法试验中的泄漏电流分析与电弧辨识

复合绝缘子的伞套材料必须具备极好的耐漏电起痕与电蚀损性,以确保其长期运行的可靠性。斜面法试验是常用的耐漏电起痕与电蚀损性试验方法,泄漏电流分析是研究斜面法试验严酷性的重要手段。设计了一种新的适用于交流斜面法试验的电弧辨识算法,对4.5 k V标准交流斜面法试验中高温硫化固体硅橡胶(HTV)样品的泄漏电流进行分析。结果表明,HTV样品的电弧特征参数分布具有长尾特性;长尾特性使得电弧特征参数不能严格地服从正态或对数正态分布。根据燃弧时间的移动平均曲线,可以将HTV样品电蚀损过程定量划分为慢速电蚀损阶段和快速电蚀损阶段。在慢速电蚀损阶段,电弧特征参数基本保持稳定;进入快速电蚀损阶段时,电弧特征参数会发生阶跃式变化。     

ATH对复合绝缘子用硅橡胶性能影响的分析

通过斜面法试验研究了不同三水氧化铝（ATH）含量对硅橡胶材料耐漏电起痕和烧蚀性能的影响。借助TG、SEM等近代仪器分析技术,研究了ATH的阻燃机理及其在硅橡胶中的分散性。试验结果表明提高ATH的含量能增加硅橡胶材料的耐漏电起痕性能,但同时也将降低其机械性能。     

ATH对复合绝缘子用硅橡胶性能影响的分析

通过斜面法试验研究了不同三水氧化铝(ATH)含量对硅橡胶材料耐漏电起痕和烧蚀性能的影响。借助TG、SEM等近代仪器分析技术,研究了ATH的阻燃机理及其在硅橡胶中的分散性。试验结果表明提高ATH的含量能增加硅橡胶材料的耐漏电起痕性能,但同时也将降低其机械性能。     

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     

环氧接枝多壁碳纳米管改性环氧树脂复合材料的热学与耐电烧蚀性能研究

通过硅烷偶联剂将环氧链段接枝到多壁碳纳米管表面,再将其加入环氧树脂中制备了环氧接枝多壁碳纳米管/环氧树脂纳米复合材料,并对环氧树脂及其复合材料的力学、热学和耐电烧蚀性能进行了研究。结果表明:接枝环氧链段的多壁碳纳米管和树脂基体有较好的界面相容性,环氧接枝多壁碳纳米管的加入使复合材料的拉伸强度和断裂伸长率分别提高了52.98%和72.86%。随着环氧接枝多壁碳纳米管质量分数的增加,复合材料的玻璃化转变温度和热导率均有所提高,在质量分数为0.8%时分别提高了11.15℃和37.57%。较低填料含量下,环氧接枝多壁碳纳米管的加入对环氧复合材料的耐电烧蚀时间影响不大,环氧接枝多壁碳纳米管质量分数为0.05%的复合材料平均耐电烧蚀时间比纯环氧树脂增加了5 s。     

室温硫化硅橡胶防污闪涂料老化分析及评估方法研究

RTV防污闪涂料是电力系统中广泛采用的防污措施,能够有效提高电力系统外绝缘耐污性能。但作为一种高分子材料,RTV涂料的耐候性并不理想,在长期运行中可能出现起皮、脱落、粉化等现象进而影响耐污性能。文中以同一厂家、不同运行环境下的RTV防污闪涂料样品作为研究对象,分析了涂料的性能指标及微观结构变化情况。分析发现,RTV防污闪涂料在运行后会出现有机基团含量下降、二氧化硅成分增加等现象,且高温高湿环境中样品的老化更为严重。研究表明,老化后的RTV防污闪涂料热稳定性下降,有机组分减少,利用X射线衍射分析能够识别RTV防污闪涂料中的二氧化硅成分变化,可以用于防污闪涂料的状态评估。     

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。     

The role of inorganic fillers in silicone rubber for outdoor insulation alumina tri-hydrate or silica

A systematic study to understand how alumina tri-hydrate (ATH) and silica fillers improve the erosion resistance of silicone rubber during dry band arcing showed that the thermal conductivity of the resulting composite material is the main criterion governing material erosion. The thermal conductivity of the composite material is dependent on the thermal conductivity, concentration, particle size, and bonding of the filler particles to the silicone matrix. In this context, either filler can be shown to perform better than the other, depending on the formulation, in the ASTM inclined plane tracking and erosion test. Therefore, the industry perception that ATH filler imports better erosion resistance than silica in silicone rubber can be misleading. The release of water of hydration from ATH appears to have a secondary effect that may be more relevant in silicone compositions having a low concentration of a filler.     

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     

Erosion resistance of nano-filled silicone rubber

The paper presents the experimental results obtained on the erosion resistance of silicone rubber (SIR) filled with 12 nm size fumed silica (nano filler) to those filled with 5 /spl mu/m size silica filler (micro filler). The ASTM 2303 inclined plane tracking and erosion test was used in the comparison as well as an infrared laser as the source of heat to erode the SIR samples. The erosion resistance of the SIR materials increased with increasing percentage of the fillers, and it was observed that 10% by weight of nano-filled SIR gives a performance that is similar to that obtained with 50% by weight of micro-filled SIR. The low frequency components of leakage current and the eroded mass are used to evaluate the relative erosion resistance of the composites and the third harmonic component of the leakage current shows good correlation to the measured eroded mass. The paper discusses the possible reasons for the improvement in the erosion resistance of nano-filled silicone composites.     

Thermal conductivity of filled silicone rubber and its relationship to erosion resistance in the inclined plane test

Silicone rubber samples having various concentrations and mean particle sizes of either alumina tri-hydrate or silica filters, prepared by room temperature and heat cured under pressure (hot pressed), are tested for erosion resistance in the ASTM D2303 inclined plane tracking and erosion test. Their corresponding thermal conductivities are determined using a transient temperature technique in which an infrared laser is employed as the heat source and a thermal imaging camera as a temperature detection device. Scanning electron microscope observations show greater filler bonding to the silicone matrix in the hot pressed samples than in the room temperature vulcanized samples leading higher thermal conductivity and increased resistance to erosion, for both ATH and silica filled samples. The correlation study shows a strong relationship between the erosion resistance and the thermal conductivity of the tested samples, highlighting the importance of an outdoor insulating material to have high thermal conductivity in order to withstand dry band arcing. The results can be used to provide guidance on filler selection for silicone rubber compounding for outdoor insulation applications.     

Influence of single and multiple environmental stresses on trackingand erosion of RTV silicone rubber

Single and multiple effects of UV, corona, thermal, water absorption and acid rain stresses on the tracking and erosion characteristics of room temperature vulcanized silicone rubber (RTV) are investigated. It is shown that corona stress and water absorption stress decrease the tracking and erosion resistance of RTV, while thermal stress and UV stress improve it. Synthetic acid rain, 500× stronger than actual rain in Japan, cannot induce the change in the tracking and erosion characteristics. RTV subjected to simultaneous multiple stresses also is evaluated. Significant variations in the tracking and erosion resistance appear. Chemical and morphological analysis for assessing the aging level is carried out by scanning electron microscope (SEM)-energy dispersive X-ray (EDX), attenuated total reflection (ATR)-Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC). In this study, DSC plays an important role to detect boiling and combustion temperatures of byproducts affecting tracking and erosion. Noteworthy results are obtained in that the decrease in the resistance to tracking and erosion is related to the formation of byproducts that burn at low temperature (170 to 275°C)     

纳米TiO2对RTV硅橡胶涂膜导电的影响

为了解纳米二氧化钛(TiO2)对室温硫化(RTV)硅橡胶涂膜半导体导电行为影响的规律,采用电位-电容法结合Mott-Schottky分析技术研究了在硫酸钠的质量分数w(Na2SO4)=5%的硫酸钠溶液中纳米二氧化钛对RTV硅橡胶涂膜的导电行为的影响。研究发现,添加纳米二氧化钛粉体后,RTV硅橡胶涂膜的空间电荷层电容Csc减小,该涂膜的空间电荷层厚度增加。随着浸泡时间的延长,涂膜的空间电荷层电容Csc逐渐增加,表明涂膜的空间电荷层厚度随浸泡时间延长而有逐渐减小的趋势。添加纳米二氧化钛粉体,可促进RTV硅橡胶涂膜的导电行为由n型半导体导电特征转变为p型半导体导电特征,当所添加的纳米二氧化钛的质量分数w(TiO2)=2%时,RTV硅橡胶涂膜转变为绝缘态。     

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。     

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。     

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。