Study on the Mechanism of Adhesion Improvement Using Dry-Ice Blasting for Plasma-Sprayed Al2O3 Coatings

Improved adhesions of plasma-sprayed Al₂O₃ coatings are achieved by using dry-ice blasting. Therefore, it is important to understand the mechanisms involved. In this study the surface roughness of different substrates treated by dry-ice blasting was firstly examined. And then the surface wettability was characterized in order to clarify the effect of dry-ice blasting on the substrate surface properties. The dry-ice blasting parameters, blasting angle, dry ice flow rate, distance etc., were investigated to identify their influences. The residual stress of plasma-sprayed Al₂O₃ coatings using dry-ice blasting was measured and compared with that of coatings deposited with conventional air cooling. Based on these numerous assessment tests, it could be concluded that the optimization of substrate preparations by dry-ice blasting was determined to be the most important influence on the adhesion improvement of Al₂O₃ coatings.