Improvement in the microstructure and property of plasma sprayed metallic, alloy and ceramic coatings by pre-/during-treatment of dry-ice blasting

摘要

Dry-ice blasting was introduced into plasma spray as substrate's under-cooling system to improve the microstructure and property of coatings. In this study, steel, CoNiCrAlY and Al_2O_3 coatings were deposited by plasma spray coupled with the pre-/during-treatment of dry-ice blasting. Moreover, the effect of dry-ice blasting as a pre-/during-treatment and only the during-treatment was examined to discover a better way to use dry-ice blasting during thermal spraying. It is revealed that a denser steel or CoNiCrAlY alloy coating with a lower content of oxide can be achieved with the application of dry-ice blasting during the plasma spraying. Such decrease of the oxide content is mainly attributed to the better cooling effect of dry-ice pellets. Interestingly, it is also found that the pre-treatment of dry-ice blasting on the substrate can help to get metallic, alloy and even ceramic coatings with improved adhesions. The adhesive strengths of steel, CoNiCrAlY and Al_2O_3 coatings were increased by 14%, 5% and 30%, respectively, compared with those of the coatings deposited with conventional air cooling. The cleaning effect of dry-ice blasting is responsible for the increase of the adhesive strength. Based on the present study, dry-ice blasting can be proposed as a pretreatment and cooling system during plasma spray.