Study of Test Method for Adhesion of Hydrophobic Insulating Coating on Insulator Metal Fitting Surface

At present, the phenomenon of corrosion of insulator on direct current (DC) transmission line is prominent, it is possible to prevent insulator from being corroded by adding a hydrophobic insulation coating on the surface of the insulator. Silicone rubber (PRTV) coatings are commonly used as hydrophobic insulation coatings, but the adhesion of PRTV coatings on the surface of insulator metal fitting is not good. The test methods for coating adhesion currently given in China are relatively simple and lack quantitative indicators. In this paper, the adhesion test methods of PRTV and polyvinylidene fluoride (PVDF) on the surface of A3 steel and hot-dip galvanized metal are studied, and to research the effect of dopamine as an intermediate adhesion promoter. First, two kinds of metal coating tests were prepared, and a pull-off test device was set up. According to the pull-off test, it was found that when different coating samples were bonded to the test metal fixture, the bonding effect was significantly different. When PRTV coating samples are bonded to test columns, need to use fast-drying cyanoacrylate adhesive, epoxy adhesive cannot effectively bond PRTV samples and fixtures. When PVDF coating samples and test columns are bonded, the adhesion of epoxy resin adhesive is much stronger than fast-drying cyanoacrylate adhesive. The experimental test results show that after dopamine is used as the intermediate adhesion layer, the adhesion of the PVDF coating on the galvanized substrate is stronger than the ungalvanized sample; the ungalvanized PVDF sample has about 2 times the adhesion improvement than the galvanized PRTV sample; Under the situation that the adhesion of ungalvanized PVDF samples is enhanced, the adhesion of galvanized PVDF samples is about 2 times higher than ungalvanized PVDF samples. It can be found that PVDF coatings have significantly improved the adhesion index compared to PRTV coatings. This article can provide a reference for the requirements of insulator coating adhesion test.