Corrosion studies on tailored Zn·Co aluminate/kaolin core–shell pigments in alkyd based paints

Abstract

Core–shell theory presents a new easy route to obtain high performance, and eco-friendly anticorrosive pigments with concomitant savings. This theory is based on depositing a surface layer of expensive efficient anticorrosive pigment on a cheap extender expressing the bulk. The combination of both core and shell compounds led to the production of new pigments with improved properties different from each of its individual components; and consequently these improved properties lead to change in the efficiency of protection properties of paint films containing these new pigments. The objective of the present work is to prepare a new ecologically friendly inorganic pigment, based on the solid–solid interaction of cobalt oxide with zinc oxide on surface of kaolin. The species of CoO and ZnO are susceptible to react with alumina part in the kaolin forming Zn·Co aluminate/kaolin. The new pigment will be incorporated in medium oil alkyd-based paints. The effect of cobalt aluminate/kaolin, zinc aluminate/kaolin individually and zinc·cobalt aluminate/kaolin on the protection performance of paint films containing them will be compared and studied. Another comparison will be held out between films containing nano- and micro-zinc·cobalt aluminate/kaolin to determine the best among the prepared pigments for better corrosion prevention. The comparison will be done using accelerated laboratory test for 28 days in artificial sea water and electrochemical impedance spectroscopy. The results revealed that nano-pigments and pigments containing higher concentration of zinc were the best in protecting steel substrates.