Novel thermal barrier coatings based on La2(Zr0.7Ce0.3)2O7/8YSZ double-ceramic-layer systems deposited by electron beam physical vapor deposition

Thermal cycling behavior of YSZ and La2(Zr0.7Ce0.3)2O7 as double-ceramic-layer systems EB-PVD TBCs

“…1c, implying that the as-decomposed La 2 O 3 , ZrO 2 and excess CeO 2 (or formation from the further oxidation of Ce 2 O 3 ) could be incorporated into the coating. As a result, the main fluorite structure of La 2 (Zr x Ce 1−x ) 2 O 7 can be strongly further formed, because the temperature of thermal cycling test adopted in this study is ∼1573 K, which is higher than that of temperature investigated in our previous work [16]. This result is in good agreement with the previous investigation by Cao [6].…”

“…The premature failure of single LZ7C3 coating can be mainly related to the chemical incompatibility of LZ7C3 coating and TGO layer and its sharp decrease of thermal expansion coefficient at low temperature (6.59 × 10 −6 K −1 , 538 K) [10,11]. The failure behaviors of single LZ7C3 coating in this study are similar to our previous investigation at 1373 K in an air furnace [16].…”

“…8a-h, and this thin layer is so-called as the thermally grown oxide (TGO) layer, implying that bond coat oxidation is still an important factor for coating failure. The thickness of TGO layer observed in this study after failure is much thinner than that of one reported in our previous investigation [16]. The internal-oxidation of bond coat usually occurs by both the oxygen penetration through the inter-columnar gaps in the ceramic coating and oxygen-diffusion through the crystal lattice of the coating material [30].…”

“…However, little is known about the factors governing the delamination resistance of those DCL coatings upon thermal cycling at temperatures of relevance in gas turbine engines. In our former work, the failure of DCL LZ7C3/YSZ coating and its thermal cycling lifetime tested at 1373 K in an air furnace were studied [16]. To meet the requirements of the next generation of advanced engines, as a continuing work, the optimized EB-PVD processing conditions were adopted for deposition of the DCL coating of LZ7C3/YSZ and its thermal cycling behavior was tested at 1573 K in burner-rig with a coal gas flame, and then the failure mechanism was also studied.…”

Precipitation phases in the nickel-based superalloy DZ 125 with YSZ/CoCrAlY thermal barrier coating

“…To meet the requirements of an increase of turbine inlet temperature and thermal efficiency in modern advanced gas turbine, thermal barrier coatings (TBCs) have been widely applied onto the surfaces of the gas turbine components by various methods such as plasma spraying and electron beam physical vapor deposition (EB-PVD). The application of TBCs greatly enhances the operating temperature and efficiency of gas turbine, and significantly improves the component durability [4][5][6]. State-of-the-art TBCs usually consist of PtAl diffusion or MCrAlY overlay bond coat (BC) and ceramic top coat.…”