RTV涂层厚度对修复老化复合绝缘子机械性能的影响

Effect of RTV Coating Thickness on Mechanical Properties of Repairing Aged Composite Insulators

复合绝缘子的伞裙护套由于老化或机械应力,其表面会出现裂纹,使用室温硫化硅橡胶(RTV)进行修复是现场常用的方法。关于涂覆厚度的研究鲜有报道。文中以高温硫化硅橡胶(HTV)为底材,采用RTV对其裂纹进行修复,以模拟复合绝缘子表面涂覆RTV的情况。借助拉伸试验机,研究了不同裂纹形式下不同RTV涂覆厚度对其拉伸强度,拉断伸长率,弹性模量及硬度的影响。试验发现,由于存在应力集中现象,有裂纹试样的拉伸性能明显低于无裂纹试样。涂覆RTV涂层后,能够对材料的拉伸性能起到一定的修复作用,而且厚度越大,修复作用越明显。但厚度增大,双层介质硬度下降,硅橡胶韧性变大,对外界物体入侵的局部抵抗能力降低,影响复合绝缘子的机械性能,所以RTV涂层不宜过厚。

Cracks usually would appear on the surface of shed and housing of composite insulators due to aging or mechanical stress.The use of room temperature vulcanized silicone rubber(RTV)for repairing is a commonly used method.But there are few studies have been reported on coating thickness.In this paper,the high temperature vulcanized silicone rubber(HTV)is used as the basic material,while RTV is used to repairing cracks to simulate the surface of composite insulator coated by RTV.The effects of different RTV coating thickness on tensile strength,elongation at break,modulus of elasticity and hardness are investigated by means of tensile testing machine.It is found that the tensile properties of cracked specimens are lower than those without cracks due to stress concentration.Coated with RTV coating,the tensile properties of the material can play a certain role for repairing,and the greater thickness is,the more obvious repair effect turn out.But with the thickness increases,the hardness of double layer medium decreases,or the toughness of silicone rubber becomes larger.Thus,the local resistance of silicone rubber to the invasion of external objects decreases,which affects the mechanical properties of composite insulators.Therefore,RTV coating should not be too thick.