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<p>High-entropy zirconates (HEZ) are a novel class of advanced materials developed recently with promising potential as a topcoat application in the next-generation thermal barrier coating systems. HEZ has the potential to exhibit excellent phase stability and resistance to sintering. These materials offer a possible alternative to conventional 8&#xa0;wt.% yttria-stabilized zirconia (8YSZ), which has been the industry standard but exhibits performance limitations during prolonged exposure at high temperatures. This study investigates the isothermal oxidation behavior of HEZ with a chemical composition of (Y<sub>0.2</sub>Nd<sub>0.2</sub>Gd<sub>0.2</sub>Sm<sub>0.2</sub>Dy<sub>0.2</sub>)<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> exposed at 1000&#xa0;°C for up to 100&#xa0;h. The HEZ topcoat was thermally sprayed by suspension plasma spraying on a YSZ interlayer and an HVOF-sprayed MCrAlY bond coat. A Mettech Axial III torch was used to deposit the topcoats, which were produced with two distinct microstructures: columnar and dense vertically cracked. Isothermal oxidation tests were done at 5, 25, 50, and 100&#xa0;h to assess the performance of topcoats. Results show that the HEZ coatings retained a single-phase structure, with lower sintering rates, reduced porosity evolution, and reduced TGO growth compared to YSZ coatings. These findings demonstrate good thermal and microstructural stability of HEZ at 1000&#xa0;°C. However, further work is required to evaluate their long-term behavior at higher service temperatures.</p>

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Isothermal Oxidation Performance of High-Entropy Zirconate as an Advanced Topcoat for Thermal Barrier Coatings

  • 期刊论文

  • 发表日期：

    2025年10月27日

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  • Hamideh Vakilifard,
  • Fadhel Ben Ettouil,
  • Rogerio S. Lima,
  • Martin D. Pugh,
  • Christian Moreau

摘要

High-entropy zirconates (HEZ) are a novel class of advanced materials developed recently with promising potential as a topcoat application in the next-generation thermal barrier coating systems. HEZ has the potential to exhibit excellent phase stability and resistance to sintering. These materials offer a possible alternative to conventional 8 wt.% yttria-stabilized zirconia (8YSZ), which has been the industry standard but exhibits performance limitations during prolonged exposure at high temperatures. This study investigates the isothermal oxidation behavior of HEZ with a chemical composition of (Y0.2Nd0.2Gd0.2Sm0.2Dy0.2)2Zr2O7 exposed at 1000 °C for up to 100 h. The HEZ topcoat was thermally sprayed by suspension plasma spraying on a YSZ interlayer and an HVOF-sprayed MCrAlY bond coat. A Mettech Axial III torch was used to deposit the topcoats, which were produced with two distinct microstructures: columnar and dense vertically cracked. Isothermal oxidation tests were done at 5, 25, 50, and 100 h to assess the performance of topcoats. Results show that the HEZ coatings retained a single-phase structure, with lower sintering rates, reduced porosity evolution, and reduced TGO growth compared to YSZ coatings. These findings demonstrate good thermal and microstructural stability of HEZ at 1000 °C. However, further work is required to evaluate their long-term behavior at higher service temperatures.