Characterization of flaky aluminum pigments multi-coated by TiO2 and SiO2

In order to improve the anti-bacterial, dispersibility and anticorrosive properties, flaky aluminum pigments were firstly coated with SiO2 and then TiO2 by the sol–gel method. The effects of all the formulation factors, such as pH, calcination temperature and the dosage of surfactant were thoroughly investigated. The stability of the aluminum pigments in acid was examined by measuring the volume of hydrogen generated. The properties of coated flaky aluminum pigments were characterized by FTIR, SEM and EDS. The results showed that the optimal pH was 3. The effective calcination temperature was around 873 K and the appropriate concentration of a surfactant was 0.07 mol/L. FTIR and SEM studies showed that there was good connectivity between TiO2- and SiO2-coated aluminum pigments. Furthermore, a simple model is proposed to estimate the thickness of coated layers and the relationship between coating thickness and coating conditions was explored.