Residual stresses in plasma sprayed alumina and chromia coatings and their effect on wear

摘要

Plasma sprayed oxide coatings such as alumina and chromia are widely used as corrosion and wear resistant coatings in industry. In some industrial applications these coatings are the only possible solution for harsh environment. However, plasma sprayed coatings have always some open porosity. Due to porosity and lamellar structure of sprayed coatings there is a need to improve their properties. One way to enhance wear and corrosion resistance of sprayed coating is sealing treatment. Many types of organic and inorganic sealants can be used for plasma sprayed coatings. Organic sealants are usually for low temperature applications and their main function is to increase corrosion resistance of the coating. Sol-gel coatings and also liquid metals have been used as inorganic sealants [1-5]. Our earlier studies have pointed out that inorganic aluminum phosphate sealing treatment is very effective method for improving alumina and chromia coating properties such as dry abrasion resistance, erosion resistance and in some cases slurry erosion and wet abrasion resistance [6-8].