Corrosion And Leaching Study Of Low Copper (I) Oxide Paints For Antifouling Application
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Global environmental concern/economy challenges necessitate innovation of AFP's with novel additives offering improved corrosion protection, and biofouling resistance. Dispersing large proportions (40-70%) of Cu/Cu2O in paints although inexpensive produces excessive leaching & heavy accumulation of copper in marine. This study aims at formulating AFP's with reduced Cu2O levels along with novel additives, targeting controlled copper release around 15 ug/cm2/day. In the present study several formulations were prepared using Viscoplex (PAMA in mineral oil), Ionomer ED-SPAN and CuDDP. Substitute ocean water was prepared to simulate marine environmental conditions and perform leaching studies of different formulations. A variety of preliminary elimination tests monitoring; copper leach rates, corrosion and degradation of coating properties were used to eliminate those additive formulations which demonstrated poor feasibility of antifouling and corrosion protection. Formulations with viscoplex and ionomer demonstrated better control over leach rates both in terms of reducing burst release and sustaining constant release of copper. In the second part of the study the selected additives (from part I study) were combined using the DOE approach to obtain an optimized combination which would exhibit good control over the leaching rates and an improved protection against corrosion. In this regard a blend series (with additives and biocide blended together in paint) and a top-coat series (with additives and biocide in separated coating layers) were examined and compared. ICP analysis was performed to quantify and compare copper release rates of different coatings. Nano-Mechanical studies, Optical microscopy, and scanning electron microscopy techniques were used to evaluate and characterize the mechanical properties and corrosion behavior of coatings. The experimental findings suggest improved performance compared to commercial coatings in many regards. The blend series demonstrated better control on leach rate renewal while the top coat formulations had better control over the burst release. Long-term study with fouling species is desirable to substantiate the improved performance of the formulated coatings.