The influence of the ZrO2 powder dispersion on the solid solutions formation during complex stabilization

DOI: 10.62564/M4-AM2139

Alina Makudera¹, Sergej Lakiza², Olena Dudnik¹, Viktor Red'ko<sup>1

1</sup>Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine
²Center of Excellence in Nanophotonics, Advanced Materials and New Technologies Based on Crystal, Growth, Poland


Thermal barrier coatings (TBC) are widely used in modern gas turbine engines to reduce the temperature of metal surfaces in turbine sections and combustion chambers, which can increase their service life and prevent the base material degradation. The coated product must withstand very high temperature, its cyclic change and stresses caused by temperature changes and operating conditions. The standard material of the thermal barrier coating (TBC) ceramic layer, ZrO2-based solid solution, stabilized (6−8% (wt.)) Y2O3 (YSZ), has approached the temperature limit of its application (<1200 °C) due to sintering and phase transformation of t'-phase ZrO2 → T-ZrO2 + F-ZrO2 with subsequent formation of M-ZrO2. The creation of a new generation of TBC based on a ZrO2 solid solution comprehensively doped with REE oxides of the yttrium subgroup (heavy concentrate, HC) is relevant. The goal of the investigation is to determine the influence of the initial ZrO2 powder dispersion on the phase transformations of a ZrO2-based solid solution, comprehensively doped with a rare earth elements oxides mixture after heat treatment at 1400 °С. The composition for the investigation was chosen (wt.%): 70 M-ZrO2 + 30 HC. Two M-ZrO2 powders were used: nanocrystalline, obtained by the hydrothermal method, and fine-grained, industry produced. The mixtures were prepared by the ceramic method and fired at 1400 °C for 4-10 hours. Sampling was carried out after 2 hours. According to X-ray phase analysis, it was determined that the formation of T-ZrO2 in a mixture with hydrothermal M-ZrO2 begins after 4 hours of exposure, and in a mixture with fine-grained M-ZrO2 – after 8 hours. The final phase transformation M-ZrO2 → T-ZrO2 in both cases was completed after exposure for 10 hours. The first traces of T-ZrO2 were detected in a mixture with hydrothermal M-ZrO2 after 4 hours of exposure, and in a mixture with fine-grained ZrO2 – after 8 hours. Finally, M-ZrO2 disappears after an exposure for 10 hours.

Keywords
ZrO2, oxides REE, complex stabilization, solid solution

Acknowledgments
Not provided

References
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