EBPVD热障涂层的微孔结构和性能.pdf

Surface and Coatings Technology 168 (2003) 23–29 Effect of thermal exposure on the microstructure and properties of EB-PVD gradient thermal barrier coatings a,b, a c a Hongbo Guo *, Shengkai Gong , Khiam Aik Khor , Huibin Xu aSchool of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing, PR China b ¨ ¨ Institut fur Werkstoffe und Verfahren der Energietechnik 1, Forschungszentrum Julich GmbH, 52425 Julich, Germany cSchool of Mechanical Production Engineering, Nanyang Technological University, Nanyang Avenue 639798, Singapore, Singapore Received 11 June 2002; accepted in revised form 10 December 2002 Abstract The effects of thermal exposure on the microstructure, properties and failure of electron beam physical vapor deposited Al O – 2 3 yttria stabilized zirconia (YSZ) gradient thermal barrier coatings (GTBCs) were studied. The GTBCs, with lifetimes of more than 500 h for 1-h cycles and 13 h for 0.25-h cycles at 1100 8C, exhibited a better thermal shock resistance than two-layered- TBCs consisting of a NiCoCrAlY bond coat and a YSZ topcoat. The GTBCs also showed a relatively low oxidation rate under cyclic exposure, due to the formation of a pre-deposited Al O film on the bond coat. The oxidation of the bond coat is dominated 2 3