Comparison of Rare Earth Phosphating and Chromate Phosphating on Aluminum Alloy

The performance of the chemical conversion coatings formed on 6061-aluminum alloy with chromate phosphate process and phosphate process with rare earth as additive was studied by electrochemical measurement,immersing corrosion test and adhesion test.The results showed that the film forming processes were different.In the weak polarized scope,both of the corrosion resistance were close,but in the strong polarized scope,the corrosion resistance of the films formed by chromate phosphate process was better than that by phosphate process with rare earth as additive.Adhesion force between the conversion coating formed by phosphate process with rare earth as additive and the organic coating surpassed that of chromate phosphate process.