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Effect of Heat Treatment in the Temperature Range 400−1300°C on the Properties of Nanocrystalline ZrO2−Y2O3−CeO2 Powders

Effect of Heat Treatment in the Temperature Range 400−1300°C on the Properties of Nanocrystalline... The properties of nanocrystalline powders of compositions (mol.%) 97 ZrO2–Y2O3, 95 ZrO2–3 Y2O3–2 CeO2, 92.5 ZrO2–2.5 Y2O3–5 CeO2, 90 ZrO2–2 Y2O3–8 CeO2, and 88 ZrO2–12 CeO2 were studied. The powders were produced by hydrothermal synthesis in an alkaline environment from a coprecipitated hydroxide mixture with a residual moisture of 15–20%. The powder properties were determined by X-ray diffraction (XRD), electron microscopy, BET, and petrography. Metastable F-ZrO2 was found to form in the hydrothermally synthesized powders. According to XRD, the F-ZrO2 → T-ZrO2 phase transformation began at 700°C and finished at 850–1000°C. The crystal optical characteristics of the powders indicate that the F-ZrO2 → T-ZrO2 phase transformation started at 400°C. The variations in F-ZrO2 and T-ZrO2 unit cell volumes are associated with lattice distortions under the action of different mechanisms in costabilization of the zirconia-based solid solution and with the ratio of Y2O3 and CeO2 in the solid solution. The tetragonality of the powders increases in the ZrO2 costabilization. The transformation strengthening mechanism for ceramics based on ZrO2 (Y2O3, CeO2) solid solutions becomes more effective with the formation of T-ZrO2, whose capability to the T-ZrO2 → M-ZrO2 phase transformation increases. The morphology of the powders varies topologically continuously, and the sizes of their primary particles hardly increase up to 1150°C. The variation in the specific surface area (from 153 to 2 m2/g) of the powders is determined by the F-ZrO2 → T-ZrO2 phase transformation and their sintering activity above 1000°C. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Powder Metallurgy and Metal Ceramics Springer Journals

Effect of Heat Treatment in the Temperature Range 400−1300°C on the Properties of Nanocrystalline ZrO2−Y2O3−CeO2 Powders

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References (51)

Publisher
Springer Journals
Copyright
Copyright © Springer Science+Business Media, LLC, part of Springer Nature 2021
ISSN
1068-1302
eISSN
1573-9066
DOI
10.1007/s11106-021-00251-z
Publisher site
See Article on Publisher Site

Abstract

The properties of nanocrystalline powders of compositions (mol.%) 97 ZrO2–Y2O3, 95 ZrO2–3 Y2O3–2 CeO2, 92.5 ZrO2–2.5 Y2O3–5 CeO2, 90 ZrO2–2 Y2O3–8 CeO2, and 88 ZrO2–12 CeO2 were studied. The powders were produced by hydrothermal synthesis in an alkaline environment from a coprecipitated hydroxide mixture with a residual moisture of 15–20%. The powder properties were determined by X-ray diffraction (XRD), electron microscopy, BET, and petrography. Metastable F-ZrO2 was found to form in the hydrothermally synthesized powders. According to XRD, the F-ZrO2 → T-ZrO2 phase transformation began at 700°C and finished at 850–1000°C. The crystal optical characteristics of the powders indicate that the F-ZrO2 → T-ZrO2 phase transformation started at 400°C. The variations in F-ZrO2 and T-ZrO2 unit cell volumes are associated with lattice distortions under the action of different mechanisms in costabilization of the zirconia-based solid solution and with the ratio of Y2O3 and CeO2 in the solid solution. The tetragonality of the powders increases in the ZrO2 costabilization. The transformation strengthening mechanism for ceramics based on ZrO2 (Y2O3, CeO2) solid solutions becomes more effective with the formation of T-ZrO2, whose capability to the T-ZrO2 → M-ZrO2 phase transformation increases. The morphology of the powders varies topologically continuously, and the sizes of their primary particles hardly increase up to 1150°C. The variation in the specific surface area (from 153 to 2 m2/g) of the powders is determined by the F-ZrO2 → T-ZrO2 phase transformation and their sintering activity above 1000°C.

Journal

Powder Metallurgy and Metal CeramicsSpringer Journals

Published: Nov 1, 2021

Keywords: ZrO2–Y2O3–CeO2 system; nanocrystalline powder; hydrothermal synthesis; zirconia-based solid solution; costabilization; transformation strengthening

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