Influence of Three Different Anions on Morphology and Property of Trivalent Chromium Based Conversion Coating on Aluminum Alloy

摘要

The influence of F-, C O 2-2 4 and Mo O 6- 7 24 as film agents on the morphology and the electrochemicalproperty of trivalent chromium based conversion coating was investigated with the methods ofscanning electronic microscope (SEM), contact angle measurement and electrochemical test. From theSEM micrograph and contact angle measurement, we observed various morphologies and propertiesfor the Cr(III)-based CCC on aluminum alloy among the specimens immersed in different solutions,and the specimen in Cr()/Mo O 6-7 24 solution displays a much smooth and dense morphology withoutnotable crevices, the value of contact angle is 112.9. The electrochemical tests showed that the anti- corrosion properties are also varied among the coatings formed in different conversion solution, whichis attributed to the different role of each agent. And we also explain the possible formation mechanismunder the influence of three different anions. All results demonstrate Mo O 6- 7 24 is the best coatingformation agent among the three anions.