Oxidation Resistance of Plasma-Sprayed Double-Layered LC/YSZ Coatings with Different Thickness Ratios at High Temperatur
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Oxidation Resistance of Plasma‑Sprayed Double‑Layered LC/YSZ Coatings with Different Thickness Ratios at High Temperatures L. Zhang1 · W. Fan2 · Y. Wang1,3 · K. Liu4 · Z. Z. Wang1 · Y. Bai1 Received: 14 April 2020 / Revised: 18 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract This study aims to enhance the oxidation resistance of ceramic coatings through designing and optimizing microstructure. A series of double-layered lanthanum– cerium oxide (LC) and 8 wt% yttria-partially-stabilized zirconia (YSZ) coatings with different thickness ratios were tailored. The isothermal oxidation experiment and molecular dynamics simulation results suggested that due to the lower oxygen ionic diffusion coefficient, double-layered LC/YSZ coatings exhibited an excellent antioxidation property compared to the single-layer YSZ coating. However, with the increase of LC layer thickness in LC/YSZ coatings, sintering-induced vertical cracks were easily formed within LC layer, which significantly shortened the oxidation resistance of LC/YSZ coatings by a burner rig test at 1225 °C. The equivalent thermal growth oxide thickness manifested that the optimum thickness ratio between LC and YSZ layers was 1:2. Keywords Thermal barrier coatings · Plasma spraying · Lanthanum–cerium oxide · Oxidation resistance · TGOs thickness
L. Zhang and W. Fan contribute equally to this work. * Y. Wang [email protected] * Y. Bai [email protected] 1
State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
2
School of Energy and Power Engineering, North University of China, Taiyuan 030051, People’s Republic of China
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State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, People’s Republic of China
4
Mechanical and Electrical Engineering Institute, Zhengzhou University of Light Industry, Zhengzhou 450000, People’s Republic of China
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Oxidation of Metals
Introduction Thermal barrier coating (TBC) is widely applied in aircraft engine and heavy-duty gas turbines to protect the hot-section components from oxidation and corrosion [1–3]. The TBC system mainly consists of superalloy substrate, metallic bond coat, thermally grown oxides (TGOs) and ceramic top coat. The failure of plasma-sprayed TBC is usually associated with the initiation and propagation of cracks induced by multiple stress during service, including thermal mismatch stress, sintering stress, thermal gradient stress and TGOs growth stress, etc. [4–7]. If the TGO is composed of a continuous scale of A l2O3, it can act as a diffusion barrier to protect the bond coat from further oxidation. However, when the Al content within the bond coat decreases to a critical level, other oxides, such as the mixed oxides of chromia, spinel and nickel (CSN) oxides, quickly grow in TGOs [8, 9]. The high growth rate and large volume expansion of these CSN oxides can cause the failure of TBCs due to the in
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