Atul Tiwari, University of Hawaii; Lloyd H. Hihara, University of Hawaii at Manoa
Organic-inorganic hybrid materials are largely being used as barrier coatings for the corrosion protection of metals. Although these hybrid ceramers possess excellent environmental stability, their long term usage in aggressive climatic conditions is still questionable. Free volume associated with these hybrid coatings often provides percolation pathways for the ions and electrolytes to reach the substrate material leading to corrosion initiation. We have recently developed a novel coating formulation consisting of a high silicone content, which significantly reduces the free volume in the coating. The hydrocarbon content was optimized to impart planarization characteristics to the solid coating. This coating precursor also etches the oxide layer of the metal surface to reveal the hydroxyl functionality for the reaction. Specialty chemicals present in the coating composition provides in-situ buffering action to control the pH of the reaction medium. Titanium nanoparticles embedded in the backbone of the coating structure provides scratch and UV resistance to the final coat. In this communication, we investigate the barrier strength of this high-silicone coating. Fourier transformation infra-red spectroscopy and Raman spectroscopy will be used to confirm the macromolecular structure of the precursor as well as the cured coating. Thermal stability of the solid coating will be assessed by thermogravimetry, and the mechanical strength will be evaluated utilizing the nanoindentation technique. Surface morphology associated with the condensed coating will be studied using scanning electron microscopy and atomic force microscopy. The comparison between coated and uncoated metal coupons exposed to outdoor test sites and laboratory corrosion experiments will be reported.