Corrosion behaviour of 7075 aluminium alloy in acidic solution

Abstract

The objective of this work was to establish the influence of sodium molybdate on the corrosion kinetics of 7075 aluminium alloy in orthophosphoric acid aqueous solution. Corrosion rate was decreased from 75.98 to 3.24 g per m2 per day. The mechanism of corrosion inhibition was studied using scanning electron microscopy, X-ray photoelectron spectroscopy, UV-Vis spectrophotometry and electrochemical impedance spectroscopy. It was revealed that heteropolyoxomolybdate species act as the corrosion inhibitor. They adsorb onto the surface and inhibit an anodic process. Their influence on a cathodic process is much weaker. Phosphomolybdenum blue species do not inhibit corrosion process and their formation is undesirable.