Simultaneously improving strength and abradability for abradable seal coatings by localized bonding hollow spheres

To solve the long-standing contradiction between the bonding strength and abradability of an abradable seal coating (ASC), a novel spherical closed-pore structure was proposed. The new structure was composed of three discontinuous phases including locally enriched metals and hollow thin-shell spheres and pores. The results show that the bonding strength of the abradable seal coating reaches 25.4 MPa, and the abrasion ratio between the coating and blade tip, as a characterization of the abradability of ASCs, is > 5900. The dewetting kinetic process of the metal film on the ceramic sphere was calculated. The size of the shrink metal hemisphere is 3.6 times metal film thickness. The locally enriched metal enables high bonding strength, while the fragmentation of the hollow thin-shell spheres enhances the abradability, thus simultaneously improving strength and abradability. The coating is expected to be used in next-generation turbines to improve efficiency and stability.