Influence of the deposition energy on the composition and thermal cycling behavior of La2(Zr0.7Ce0.3)2O7 coatings

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

“…The pyramids are oriented in plane so that their diagonal edges, corresponding to the intersection of 0 0 1 planes with the surface, are either parallel or perpendicular to the rotation axis. The pyramidal diameters are measured to be approximately 1-1.5 m, which is smaller than those of single LZ7C3 coating as observed in our previous investigation [18]. The possible reason is that the nucleation growth of randomly oriented LZ7C3 grains within single and DCL systems begins with different substrate materials.…”

“…However, the relatively low thermal expansion coefficient of LZ7C3 from room temperature to 1673 K leads to high thermal stress between the LZ7C3 coating and the metallic bond coat, and the chemical compatibility of LZ7C3 coating and thermally grown oxide (TGO) layer is unstable during thermal cycling test. Therefore, the single LZ7C3 coating usually has a short thermal cycling life as reported in previous papers [18,19].…”

“…Bulk LZ7C3 has a lower thermal conductivity (0.87 W m −1 K −1 , 1273 K) than that of YSZ (2.1-2.2 W m −1 K −1 , 1273 K) as reported by Sodeoka et al [16]. It is thermally stable up to its melting point (∼2413 K), and it has been proposed as a promising TBC material [5,15,[17][18][19]. However, the relatively low thermal expansion coefficient of LZ7C3 from room temperature to 1673 K leads to high thermal stress between the LZ7C3 coating and the metallic bond coat, and the chemical compatibility of LZ7C3 coating and thermally grown oxide (TGO) layer is unstable during thermal cycling test.…”

“…Partial decomposition of rare earth-zirconia composite oxide could occur during EB-PVD due to different vapor pressures of its compositional oxides, which inevitably leads to composition derivation of the deposited ceramic coating from the original ingot [12,18,26,27]. In such case, it is necessary to optimize the chemical composition of original ingot and processing parameters for deposition of coatings, in order to obtain the optimal phase with nearly stoichiometric composition.…”

Microstructure and Thermal Properties of Nanostructured 4 wt.%Al2O3-YSZ Coatings Produced by Atmospheric Plasma Spraying

“…The mechanism on inhibiting the grain growth of nanostructured YSZ thermal barrier coatings has been discussed in detail. The effect of small amount of La 2 O 3 (Ref [19][20][21][22][23] additions on thermal conductivity, structural stability is investigated. The addition of a small quantity of La 2 O 3 (Ref 13,14,19) is effective in improving the sintering resistance and lowering the thermal conductivity of traditional YSZ produced by air plasma spray.…”