Unique silicone-epoxy coatings for both fouling- and drag-resistance in abrasive environments

Abstract

Multiple years of international trials in both oceanic and freshwater sites have led to successful easy-release coatings based on the methyl-silicone polymers now widely employed as substitutes for tributyltin- and copper-based ship bottom paints. These have been found to be too soft for harsh conditions, especially during abrasion, but do serve for useful periods in commercial and military circumstances where abrasion is not frequent. This chapter reviews abrasion-related research of the past 20 years that identifies a novel version of silicone-based coatings with a retained easy-release value of Critical Surface Tension (CST) of about 26 mN/m, compounded with a tough epoxy component that allows the two-component coating to survive and function well in extremely abrasive circumstances. This coating has been applied to a power plant’s large intake grate (“rack”) subject to debris impact and intense zebra mussel fouling, an airfoil blade coating showing significantly lower drag than competitive paints, a turbine encasement seal layer remaining functional in zebra mussel-infested waters, and an easy-release surface for flash-frozen ice, simultaneously also resisting damage by transit through ice floes. The coating is formulated using polymeric methyl-silicone granules that are dispersed within an oil-in-water multiple emulsion in an epoxy base that maintains excellent substratum adhesion while allowing the methyl-silicone-based matter to dominate and be continuously refreshed via minimum wear at the environmental interface.