Wet abrasion and slurry erosion resistance of sealed oxide coatings

Several recently published studies have shown remarkable improvements in dry abrasion resistance and corrosion resistance of aluminum phosphate sealed oxide coatings when compared to unsealed ones. There are numerous applications in chemical industry where a corrosive environment is accompanied with abrasive or erosive particles. In this study the wet abrasion resistance and slurry erosion resistance of aluminum phosphate sealed and oxide coatings were studied and compared to their dry abrasion resistance. In wet abrasion tests kaolin and water mixture was used as the abrasive. In slurry erosion tests several abrasives in water with various pH values was used as the erosive medium. The coatings were characterized for microstructure and their wear mechanisms were analyzed using SEM. The results from wear tests are reported and correlated with coating properties. The influence of coating quality to the relative improvement achieved by sealing is presented and discussed.