Study on the Mechanism of Adhesion Improvement Using Dry-ice Blasting for Plasma-sprayed Al_2O_3 Coatings

摘要

The previous study (Ref 1) indicated that improved adhesions of plasma-sprayed Al_2O_3 coatings have been 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 effect of dry-ice blasting on Al_2O_3 splat morphology with different treatment times was investigated. The residual stress of plasma-sprayed Al_2O_3 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 cleaning effect of dry-ice blasting on different organic substances adsorbed on the substrates was the most important influence on the adhesion improvement of Al_2O_3 coatings.