Electrochemical behavior of chemical conversion of coated aluminum 1100al in a neutral tartrate solution

Abstract EN

1100 Al specimens were anodically oxidized in different concentrations of tartaric acid-tartrate solution (pH = 7) in 1, 1.75, 3.25 and 4 wt % at temperatures of 30, 37.5, 52.5 and 60 ؛C by applying a range of potentials of 30, 37.5, 52.5 and 60 V at exposure times of 40, 47.5, 62.5 and 70 min..

These four variables are manipulated through the experimental work using Box–Wilson experimental design where second order polynomial model was proposed to correlate the studied variables with the thickness of anodic film of aluminum alloy (1100) to estimate the coefficients of the proposed polynomial adopted via statistica software.

Optimum conditions for achieving the maximum film thickness are obtained from optimizing the above correlation and are found as follows : temp.

= 44 ؛C, acid conc.

= 2.8 wt %, voltage = 43.6 V, time = 54.6 min..

Stagnate Solutions of 3, 5, 10 and 25 wt % Nacl at 25 ؛C have been investigated using polarization technique at optimum conditions for anodizing.

The most important feature achieved was the great difference in behavior between the anodic polarization curves for bare and anodized aluminum in different concentrations of Nacl solutions.

The corrosion rates for anodized specimens are lower than those for unanodized ones.

The polarization behavior of anodizing specimens shows that the breakdown potentials are shifted to more noble direction than bare specimens which is more pronounced in 25 wt % Nacl solution due to anodizing.