Electrochemical Characteristics of the Rare Earth Compound Coating on 6061 Aluminum Alloy

摘要

The composite coatings were prepared on aluminum alloy by anodizing and chemical conversion method. The coatings consisted of a anodic oxide coating and a rare earth conversion coating. The surface morphology and composition of the composite coatings were analyzed by scanning electron microscopy (SEM) and energy dispersive X-rays (EDX). The electrochemical properties of the different samples were researched by Potentiodynamic polarisation and electrochemical impedance spectroscopy in a 3.5-wt.% NaCl solution. The results showed that corrosion current density of the sample with composite coatings was 3.611×10~(-9) A·cm~(-2), impedance was 6.107×10~5 Ω·cm~(-2). The composite coatings had better corrosion resistance than the sample with anodic oxide film and the aluminum alloy substrate.