Three Years Corrosion Tests of Nanocomposite Epoxy Sealer for Metalized Coatings on East China Sea

Although zinc, aluminum, and their alloys metalized coatings provide galvanic protection for steel, additional protection can be obtained by sealing the inherently porosity ranging up to 10 percent with epoxy sealer. Its purpose is to seal and reduce inherent porosity of metalized coating, to smooth the surface texture and to extend the service life. The traditional sealer mostly includes two-component epoxy primer or high build epoxy paint, so the high viscosity, large particles of inorganic pigments and fillers, and poor penetration into the pores of the sprayed metallic coating are its main shortcomings. The nanocomposite epoxy sealer is newly developed by the authors specially for sealing metalized coatings, its advantages including: (1) the 10-100 nm inorganic nano-oxide particles distributing uniformly in liquid paints and cured film; (2) low viscosity to facilitate good penetration into the pores, no need thinning and can be applied by brush, roller, air or airless spray; (3) chelating reaction to zinc or aluminum metalized coating; (4) excellent coatings adhesion and excellent performance of resisting attack by corrosive agents; (5) good to shield ultraviolet radiation. In order to check the performance of corrosion protection of arc-sprayed aluminum coating plus nano-modified epoxy sealing paint, some panels coated the above coatings system were exposed in the corrosion test site on east china sea by Zhoushan marine corrosion research institute. At least three panels were mounted respectively in the marine atmosphere zone, seawater splash zone, tidal zone and full-immersion zone. Test panels were made of low-carbon steel sheet. The size of panels is 100×200×4mm.