Promotion of the fragmentation and densification for a dense vacuum kinetic-sprayed Y2O3 coating by heat-treatment of feedstock powder

Abstract

Achieving a proper strength and properties of vacuum kinetic-sprayed (VKS) coatings has been a matter of issue. The heat-treatment of feedstock powder has been suggested as a solution to prevent porous microstructure of coatings. Unfortunately, there is still no study that clearly explains the effect of powder treatment on the two crucial deposition mechanisms in VKS (fragmentation and consolidation). Through observations and characterization of the coating microstructure and single-particle impact testing, the importance of the sufficient impact energy for dense VKS coatings is demonstrated. The results show that heat-treatment of Y2O3 powder resulted in improved mechanical properties of the coating and a dense coating structure. It is revealed that the larger heat-treated particles caused further size reduction of crystallites and consolidation via promotion of the intense fragmentation and intimate inter-crystallite bonding.