| With the increase in the working life of the DC transmission line and the increase in the voltage level,the problem of corrosion of the insulator metal-fitting has become more prominent.Through the above research,it is found that the isolation of moisture can effectively delay the corrosion rate of insulator metal-fitting.Still,the currently widely used silicone rubber(RTV)material has poor adhesion performance and a fast-aging rate in outdoor environments,which cannot effectively provide long-term protection to insulator metal-fitting.Silicone rubber and fluorinated polymer materials are commonly used hydrophobic materials.Polyvinylidene fluoride(PVDF)materials are widely used in electronic appliances and chemical fields due to their excellent weather resistance and stain resistance.This paper explores the application of PVDF fluorocarbon materials with excellent weather resistance to the protection of insulator metal-fitting.This paper focuses on the following parts:First of all,this paper uses the mature water-based PVDF fluorocarbon emulsion on the market as the main raw material and modifies the water-based PVDF fluorocarbon coating by adding auxiliary reagents.The surface pretreatment of hot-dip galvanized metal substrates used in insulator fittings are carried out by the phosphating method to improve the agglomeration of large particles of colloids produced by direct spraying of water-based PVDF coatings.Subsequently,two methods were selected to improve the adhesion of PVDF coatings:polydopamine(PDA)with super adhesion to the substrate surface modification and epoxy zinc-rich primer as a transition layer.Through the adhesion test,the adhesion of RTV on the surface of hot-dip galvanized substrate is significantly lower than that of the prepared water-based PVDF coating,and the water-based PVDF coating has the strongest adhesion on the ceramic substrate.After the surface modification of the substrate with PDA,the wettability of the substrate is improved,a strong chemical bond interaction is established between the substrate and the coating,and the adhesion of the prepared water-based PVDF fluorocarbon coating is significantly improved.At the same time,the scheme of using epoxy zinc-rich primer also significantly improves the adhesion of water-based PVDF coatings.In the test samples,the coating with 30% zinc content has the strongest adhesion,and the adhesion decreases with the increase of zinc content in the primer.Trend,at 70%,the adhesion improvement is minimal.In the test group of hot-dip galvanized metal substrates,polydopamine(PDA)improved the adhesion of water-based PVDF coatings the most.However,due to the high difficulty of PDA construction,it is currently not suitable for direct construction on the surface of insulator metal-fitting.However,the use of the epoxy zinc-rich primer treatment method has a more significant and stable improvement in adhesion at 30%content,the preparation and construction difficulty is lower,and it has the conditions for on-site construction.Finally,the prepared PVDF coating samples were subjected to high temperature,damp heat,and UVA-340 ultraviolet cyclic aging for 60 days.The hydrophobicity test of the coating was carried out by the water spray classification method,and the aged PVDF coating still maintained good hydrophobicity;meanwhile,the cross-cut adhesion test showed that the adhesion of the aged PVDF composite coating was also significantly stronger than that of the unaged RTV coating.The overall appearance of the aged composite coating is intact,and there is no cracking,blistering,peeling,or peeling off,and the chemical properties of the coating have not changed significantly.Tests show that under the test aging equivalent,the water-based PVDF composite coating can isolate moisture for a long time and prevent corrosion to the metal substrate of the insulator.Finally,based on the feasible epoxy zinc-rich primer scheme,the insulator metal-fitting protection samples with water-based PVDF coating were prepared. |
PDF Full Text Request