Comprehensive microstructural characterization and CMAS infiltration resistance of ytterbium disilicate coatings with lamellar and quasi-columnar structures

Degradation by CMAS deposits represents a considerable threat to the EBC service life. Current work contributes to understanding the response of Yb2Si2O7 coatings with lamellar and quasi-columnar structures to CMAS attack. It is revealed that the dual-phase structure in APS coating drastically improved the overall coating resistance to CMAS infiltration by enhancing the apatite-forming capability. The amorphous silica in PS-PVD coatings limited the formation of apatite sealing layer. With a continuous degradation of sand-phobic morphology, molten CMAS rapidly penetrated inside the entire coating. This study highlights that microstructure modulation of Yb2Si2O7 coating is a promising strategy for CMAS infiltration mitigation.

Automated summary

CMAS deposits pose a significant threat to the service life of EBC. This study investigates the response of Yb2Si2O7 coatings with lamellar and quasi-columnar structures to CMAS attack. The dual-phase structure significantly enhances the apatite-forming capability and improves the coating's resistance to CMAS infiltration. The presence of amorphous silica in PS-PVD coatings hinders the formation of an apatite sealing layer.