中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 20 Special 2 July 2010 |
sol-gel coating on AZ31 magnesium alloy
（1. College of Chemistry and Life Science, Shenyang Normal University, Shenyang 110034, China;
2. State Key Laboratory for Corrosion and Protection, Institute of Metal Research,
Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:An Al2O3 protective coating on magnesium alloy AZ31 was prepared by a repeated direct sol-gel process annealing at 300 ˚C and a composite coating was also deposited using Al2O3 particles dispersed sol followed by phosphating treatment and annealing at 300 ˚C. The morphologies, structures and critical adhesive loads as well as corrosion properties of the coatings were comparatively investigated by scanning electron microscopy (SEM), X-ray diffractometry (XRD), nanoscratch test and electrochemical measurement. The results show that the composite coating has a more uniform, crack-free layer and improved adhesion to the substrate as compared with that of the repeated direct sol-gel coating owing to its lower heat strain. The main phases in both coatings consist of γ-Al2O3 and δ-Al2O3 derived from annealed alumina sol, and the composite coating has an anticorrosion performance which is superior to that of the repeated direct sol-gel coating.
Key words: sol-gel; composite coating; magnesium alloy
