Effects of inorganic additions on the performance of manganese-based conversion treatments

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• 作者：I. Danilidis ; J. Hunter ; G.M. Scamans ; J.M. Sykes
• 关键词：A. Aluminium ; A. Permanganate ; B. Polarisation ; C. Pitting corrosion ; C. Oxide coating
• 刊名：Corrosion Science
• 出版年：2007
• 出版时间：March 2007
• 年：2007
• 卷：49
• 期：3
• 页码：1559-1569
• 全文大小：253 K

文摘

The electrochemical behaviour of permanganate-based no-rinse conversion coatings on AA3003-H14 aluminium alloy shows that they have promise as an alternative to toxic chromate-based coatings. A selection of inorganic additions has been made here to a simple 0.1 M KMnO₄ formulation investigated previously. The performance of the different coatings has been evaluated from potential–time and polarisation measurements in 0.5 wt % (0.085 M) NaCl solution for periods up to 3 days. The addition of fluoride ions produced no benefit, whereas Al(NO₃)₃ shows an improvement when added in small amounts. Tests with the individual ions reveal that it is Al³⁺ cations, rather than anions, which produce the greatest benefit.