Anticorrosive behavior of polyurethane coating containing hybrid attapulgite pigment

This study introduced new anticorrosive pigments by modigying attapulgite (ATP) via a silane coupling agent. An organic corrosion inhibitor, 2-mercaptobenzothiazole (MBT) was loaded on the surface of modified-ATP. The morphologies and compositional structures of ATP@MBT were characterized utilizing Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). UV–vis spectroscopy was used to study the loading and release behavior of MBT. ATP@MBT was incorporated into a polyurethane coating and the corrosion resistance of the coatings was investigated. The results demonstrate that ATP@MBT was well dispersed, with MBT loading capacity up to 4.8 wt% and release rate up to 97.5 % at pH = 3. The results of electrochemical impedance spectra (EIS) and salt spray tests show that the addition of ATP@MBT enhances the corrosion resistance of the coatings. There are two explanations for the protective mechanism of the coatings containing ATP@MBT. The barrier function of ATP enhances the shielding ability of the integral coatings. When the coating is scratched, MBT loaded on ATP is released on the exposed region and forms an adsorption film on the aluminum alloy surface to protect the substrate.