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| A RESEARCH ON pH DURING THE PROCESSION OF THE CERIUM(III) FILM FORMATION OF ALUMINUM ALLOYS BY EIS |
| GU Baoshan1; LIU Jianhua2 |
1. National Engineering Laboratory for Advanced Coatings Technology of Metal Material; China Iron & Steel Research Institute Group; Beijing 100081
2. School of Materials Science and Engineering; Beihang University; Beijing 100083 |
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Abstract Electrochemical impedance spectroscope (EIS) of B95 aluminum alloy in 0.01 mol/L CeCl3 solution was investigated to study the film formation. The changes of EIS in the film formation help to study the influence of pH on the film formation of B95 aluminum alloys. Followed is an analysis on the tested EIS based on equivalent circuit. The result shows that Ce conversion coating can not be formed when B95 aluminum alloy is in 0.01 mol/L CeCl3 solution at the pH=3.0 Increaing the [H+] of solution will do good to the dissolution and activation of aluminum alloy, and accelerate the first stage, but to disadvantage the formation of Ce(III) hydrate and oxide. As the pH increases, the rate of aluminum alloy dissolution and activation will decrease. Such decrease will affect the film formation stage. But it is good for the aggradation of the Ce(III) hydrate and oxide, and the thickness and the compactness of the film. In neutral or subacidity solution, increasing the pH of solution will do good to the final formation of Ce（III） conversion coating.
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Received: 03 November 2009
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Corresponding Authors:
GU Baoshan
E-mail: gubs@263.net
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