| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1616156 | Journal of Alloys and Compounds | 2012 | 10 Pages |
Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La2(Zr0.7Ce0.3)2O7 (LZ7C3) and yttria stabilized zirconia (YSZ) were deposited by electron beam-physical vapor deposition (EB-PVD). The thermal cycling test at 1573 K in burner-rig with a coal gas flame indicates the thermal cycling life of DCL coating is not only much longer than that of LZ7C3 coating, but also approximately 27% longer than that of YSZ coating. The superior sintering-resistance of LZ7C3 coating and the unique growth modes of columns within DCL coating are all very helpful to the prolongation of thermal cycling life of DCL coating. The failure of DCL coating is mainly a result of the reduction–oxidation of cerium oxide, the re-crystallization of some LZ7C3 fine grains, the cracks initiation, propagation and extension, the abnormal oxidation of bond coat, the degradation of t′-phase in YSZ coating and the outward diffusion of Cr alloying element into LZ7C3 coating. Since no single material that has been studied so far satisfies all the requirements for high temperature applications, DCL coating is an important development direction of TBCs.
► DCL coating has a longer lifetime than that of single layer coating of LZ7C3 or YSZ. ► The unique growth modes of columns within DCL coating. ► The presence of cerium in both Ce3+ and Ce4+ oxidation states within the coating surface. ► The spallation of DCL coating induced by transverse cracks may be the first emergence of delamination followed by spalling layer by layer. ► The outward diffusion of Cr element (bond coat) into LZ7C3 layer.
