Investigation of the size effect of mica sheets on the anticorrosion behavior of UV‐cured coatings

Abstract In this article, four different grades of mica sheets were used to investigate the influence of the size of mica sheet on the UV‐curing process and the anticorrosion performance of UV‐cured coatings. The dispersion of mica sheets in coating matrix was explored by viscosity and morphology measurements. The curing behavior of the composite coatings was studied by gel content and double bond conversion rate. The dispersing behavior of the mica sheets with different grades was investigated by SEM image and rheology measurement. And the anticorrosive performance of the UV‐cured composite coatings was studied by electrochemical measurements and neutral salt spray tests. It was found that the curing degree of the UV‐cured coating was not affected with incorporation of mica sheet as well as its size. Mica sheets with medium size (10 μm) could be more efficiently dispersed in UV‐cured coating than other grades, which helps to form a denser filler pathway and suppresses the diffusion of corrosive agents into the coating matrix, leading to the lowest water adsorption and best anticorrosion performance. After 45 days of immersion in NaCl solution, the impedance modulus of the UV‐cured composite coating with 10 μm mica sheets did not decrease and still maintained at the initial impedance value. After 1500 h's salt spray test, the corresponding coating remained intact without bubbling, peeling, corrosion, and other defects, whereas the coating with other grades of mica sheets all exhibited corrosion pits and blisters, demonstrating that the size of mica sheet played an important role in enhancing the anticorrosion performance of UV‐cured coatings.