An Al2O3 protective coating on magnesium alloy AZ31 was prepared by a repeated direct sol-gel process annealing at 300℃and a composite coating was also deposited using Al2O3 particles dispersed sol followed by phosph...An Al2O3 protective coating on magnesium alloy AZ31 was prepared by a repeated direct sol-gel process annealing at 300℃and a composite coating was also deposited using Al2O3 particles dispersed sol followed by phosphating treatment and annealing at 300℃.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 ofγ-Al2O3 andδ-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.展开更多
基金Project(2005Z023)supported by the Scientific Research Initial Funding of Chongqing University of Technology
文摘An Al2O3 protective coating on magnesium alloy AZ31 was prepared by a repeated direct sol-gel process annealing at 300℃and a composite coating was also deposited using Al2O3 particles dispersed sol followed by phosphating treatment and annealing at 300℃.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 ofγ-Al2O3 andδ-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.
