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

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