Effect of Yttrium Oxide on Phosphate Coating Performance on 6061 Al Alloy

Electrochemical measurements,scanning electron microscopy (SEM) and cross-cut test have been used to study the influence of yttrium oxide (Y2O3) on the phosphate coating performance formed on 6061 Al alloy.The results showed that Y2O3 added into the phosphating solution could cause the phosphate coating grains formed on 6061 Al alloy surface to be uniform and compact.Compared with that of the coating formed in phosphating solution without Y2O3,dropping corrosion time of the coating formed in the phosphating solution with 20 mg/L Y2O3 was prolonged,the corrosion potential increased by 30 mV and the corrosion current decreased by 0.15 mA.Corss-cut test and entire immersion experiment indicated that Y2O3 added into phosphating solution could strengthen the adhesion between phosphate coating and organic coating.