Studies On Cathodic Disbondment Of Base Coatings For Ambient Curable Fluoro-carbon Coating

As one of heavy anti-corrosion coatings, fluoro-carbon coating is provided withexcellent properties in weatherability, anti-corrosion, etc. However, due to itsrelatively low surface tension, it exhibits poor adhesion to metals, ceramics, glassand other materials. In order to improve the adhesion of the substrate with thefluoride coating, people modificate the fluorine resin and the base coating. The basecoating plays an important role in the entire coating system. It bridges the substrateand fluoro-carbon coating. Suitable base coating has good adhesive property for boththe substrate and fluoro-carbon coating, making the entire system with excellentproperties.In this work, the formulations of three different base coatings were optimized. Thecathodic disbondment of the coatings in which various scales were added werestudied. Several resins for base coatings, the pretreatment of the scales, theinfluence of various scales on the cathodic disbondment, the matching of basecoating with ambient curable fluoro-carbon coating and the comprehensiveproperties were also investigated.Main conclusions have been obtained as follows:1. Among the various resin-based coatings, MA-2 hydroxy acrylic resin-basedcoating possess the best properties, epoxy E-20 resin-based coating was the mostbrittle, MA-1 thermoplastic acrylic resin-based coating exhibited the minimumhardness. Cathode disbondment was MA-2＞E-20＞MA-1.2. With the increase of the amount of the filler scales added, the pigment/base ratioof coating system increased gradually. While with excessive amount of scales, coating adhesion, impact and bending declined. The amount of the added scalesshould be controlled to the mass fraction of 30-40% of the total solids content ofcoatings. The efficiency of stainless steel flakes and glass flakes to improve theresistance to cathodic disbondment was better than that of mica powder and zincpowder.3. The selection of titanate coupling agent resulted in better performance in thepretreatment process.4. In this thesis, fluoro-carbon over coating choosed by author showed goodcompatibility with base coatings. When covered with fluoro-carbon coating, thecoating system had higher resistance to the cathode disbondment, longer foamingtime, smaller foaming size and slower foaming speed. MA-2 and E-20 resin-basedcoatings with fluoro-carbon over coating exhibited good resistance to cathodicdisbondment.In engineering, the application of E-20 epoxy or MA-2 thermosetting acrylic resinwhich was matched to the ambient curable fluoro-carbon coating can result inexcellent resistance to corrosion.