Aluminium alloy corrosion inhibition by chromate-free composition of zinc phosphate and ion-exchanged zeolite

Corrosion inhibition of aluminium alloy D16T by natural and calcium and zinc ion‐exchanged zeolites and their compositions with phosphate pigment was studied. Clinoptilolite, a natural zeolite from Sokyrnytsia deposit (Transcarpathian region, Ukraine), has been used in this study as a basic component. Protective properties of polyurethane coatings containing ion‐exchanged zeolites were investigated in acid rain solution. Direct current polarization methods and electrochemical impedance spectroscopy were used. It was established that composition of zinc phosphate and calcium ion‐exchanged zeolite has significant anti‐corrosion synergistic effect because of deposition of protective film on aluminium alloy surface. The addition of phosphate/zeolite‐inhibiting composition to polyurethane coating offers substantial increase of its protective properties in corrosion environment compared with the use of a single phosphate pigment. Copyright © 2013 John Wiley & Sons, Ltd.