Bonding strength and thermal conductivity of novel nanostructured La_2(Zr_(0.75)Ce_(0.25))_2O_7/8YSZ coatings

摘要

The thermal protection coatings possessing functionality, reliability, and durability require appropriate bonding strength and low thermal conductivity. In this study, the novel nanostructured La-2(Zr0.75Ce0.25)(2)O-7/8YSZ (LCZ/8YSZ) coatings were deposited onto NiCoCrAlYCe coated nickel-based superalloy by atmospheric plasma spraying (APS) using the as-prepared nanostructured feedstocks. The microstructure, bonding strength, and thermal conductivity of nanostructured LCZ/8YSZ coatings were investigated. The results reveal that the microstructure of as-sprayed nanostructured LCZ/8YSZ coatings presents bi-modal distribution with some pores and microcracks. Furthermore, the microstructure of coatings is dense and the interface bonding of 8YSZ/bond coat and LCZ/8YSZ coatings is perfect. The bonding strength of nanostructured LCZ/8YSZ coatings is 25.1 MPa, which is lower than that of nanostructured 8YSZ coatings with the same thickness. The tensile failure mechanism is also analysed. The thermal conductivity of nanostructured LCZ/8YSZ coatings from 0.86 W.m(-1).K-1 to 0.33 W.m(-1).K-1 is obviously lower than that of nanostructured 8YSZ coatings from 1.24 W.m(-1).K-1 to 0.40 W.m(-1).K-1 in the temperature range from 30 degrees C to 1200 degrees C.