XPS AND CORROSION STUDIES ON ZINC PHOSPHATE COATED 7075-T6 ALUMINUM-ALLOY

X-ray photoelectron spectroscopy (XPS), combined with scanning electro n microscopy (SEM), weight loss tests and atomic absorption spectrosco py (AAS), has been applied to investigate the corrosion protection pro perties of zinc phosphate when coated on 7075-T6 aluminium alloy. XPS is consistent with the coating process leading to both physically adso rbed and chemically absorbed zinc. The former is washed away by ultras onic washing, but the chemically absorbed component, identified as ZnO (x), is incorporated into the aluminium oxide layer. This layer helps suppress the dissolution of aluminium during the corrosion process.