AN IMPROVED COATING COMPOSITION TO PROVIDE PROLONGED CORROSION PROTECTION TO ANODIZABLE METAL SURFACES AND PROCESS OF PREPARING THE SAME

摘要

The invention relates to an improved coating composition for coating anodizable metal and their alloys for providing prolonged corrosion protection, and a process of preparing the same. The improved composition provides corrosion protective coatings with self- healing property on anodizable metals such as aluminum, aluminum· alloy, magnesium or magnesium alloy. The process comprises loading a base composition with end-capped inorganic nanotubes encapsulating an active corrosion inhibitor, which when released under a stimulus of a certain pH acts in a two-way mode providing selfhealing effect, viz. formation of a passive layer and catalyzing polymerization of organic group in the organofunctional silane present in the base 15 composition. The coatings from the improved composition when deposited on anodizable metals and their alloys were found to provide substantial corrosion protection under prolonged exposure to a 3.5 wt % chloride containing corrosive medium.