Enhanced Corrosion Resistance and Photocatalytic Properties of Bi₂O₃/Phosphate Composite Film Prepared on AZ91D Magnesium Alloy by Phosphating

摘要

A Bi2O3/phosphate composite film was prepared on AZ91D magnesium alloy by phosphate treatment.The surface morphology, chemical composition and corrosion resistance of the composite film wereinvestigated by SEM, EDS, XPS and electrochemical measurements. Meanwhile, the wettability of thecomposite film was examined by contact angle measurements. The results showed that the compositefilm was mainly composed of CaHPO4 and Bi2O3, and the thickness of the film was approximately 15μm. The corrosion current density of the Bi2O3/phosphate composite film-coated sample was 100 timeslower than that of bare AZ91D. Immersion tests conducted in ASTM D1384-87 solution demonstratedthe durability of the composite film-coated AZ91D. Furthermore, the composite film possessedphotocatalytic activity, which could protect Mg alloy from corrosion by atmospheric pollutants.