Investigation of Cerium-Lithium Sealing Treatment of Cobalt-based Conversion Coatings Formed on Aluminum Alloys

Shubai LI, Di MA, Zhenzhen XU, Pei YAO, Yuan LIU, Yutao SUN

Abstract


A study was conducted to examine methods of adjusting cerium-lithium sealing process parameters in order to improve the corrosion protection capabilities of a cobalt-based chemical conversion film. In order to seal the pores of the cobalt-based conversion coatings, samples were treated in a cerium-lithium deposition bath in optimal process conditions. The optimal treatment condition was determined by examination of finished samples using the scanning electron microscope (SEM) and electrochemical test measurements. The corrosion behaviors of the sealing coatings were studied using an open circuit potential-time monitoring technique (OCPT), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization tests in 3.5 wt.% NaCl solution. It was found that the best treatment process for the cobalt-based conversion coating was sealed in the cerium-lithium sealing solution for 2 h at 90 ℃.

DOI: http://dx.doi.org/10.5755/j01.ms.24.4.19132


Keywords


cerium; sealing treatment; aluminum alloy; corrosion resistance

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Print ISSN: 1392–1320
Online ISSN: 2029–7289