Corrosion Resistance of Al-12Si Coatings on AZ91 Magnesium Alloy Prepared through Flame Spray

In this study, Al-12Si alloy coatings with different thickness were prepared through flame spray on the surface of the AZ91 magnesium alloy to improve its corrosion resistance. The corrosion resistance was characterized through corrosion potential using electrochemical methods. The Al-12Si alloy coatings were heat treated at 100 degrees C, 200 degrees C and 300 degrees C for 6, 12, 18 and 24 hours. The effects of heat treatment temperature and time on the coatings' corrosion resistance were discussed. It was found that there were no phase changes during the deposition of Al-12Si coatings through flame spray and heat treatment. The greater the coating thickness was, the higher the corrosion potential was. After annealing, the inner microstructure of the Al-12Si coating was densified furtherly and the annealed coatings had higher corrosion potential and better corrosion resistance. The coating annealed at 100 degrees C for 18 hours had the highest corrosion potential and the best corrosion resistance in the same coating thickness.