Mechanism of Reduced Sintering Temperature of Al2O3–ZrO2 Nanocomposites Obtained by Microwave Hydrothermal Synthesis
AbstractA novel method to obtain Al2O3–ZrO2 nanocomposites is presented. It consists of the co-precipitation step of boehmite (AlO(OH)) and ZrO2, followed by microwave hydrothermal treatment at 270 °C and 60 MPa, and by calcination at 600 °C. Using this method, we obtained two nanocomposites: Al2O3–20 wt % ZrO2 and Al2O3–40 wt % ZrO2. Nanocomposites were characterized by Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and transmission electron microscopy. Sintering behavior and thermal expansion coefficients were investigated during dilatometric tests. The sintering temperatures of the nanocomposites were 1209 °C and 1231 °C, respectively—approximately 100 °C lower than reported for such composites. We attribute the decrease of the sintering temperature to the specific nanostructure obtained using microwave hydrothermal treatment instead of conventional calcination. Microwave hydrothermal treatment resulted in a fine distribution of intermixed highly crystalline nanoparticles of boehmite and zirconia. Such intermixing prevented particle growth, which is a factor reducing sintering temperature. Further, due to reduced grain growth, stability of the θ-Al2O3 phase was extended up to 1200 °C, which enhances the sintering process as well. For the Al2O3–20 wt % ZrO2 composition, we observed stability of the zirconia tetragonal phase up to 1400 °C. We associate this stability with the mutual separation of zirconia nanoparticles in the alumina matrix. View Full-Text
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Koltsov, I.; Smalc-Koziorowska, J.; Prześniak-Welenc, M.; Małysa, M.; Kimmel, G.; McGlynn, J.; Ganin, A.; Stelmakh, S. Mechanism of Reduced Sintering Temperature of Al2O3–ZrO2 Nanocomposites Obtained by Microwave Hydrothermal Synthesis. Materials 2018, 11, 829.
Koltsov I, Smalc-Koziorowska J, Prześniak-Welenc M, Małysa M, Kimmel G, McGlynn J, Ganin A, Stelmakh S. Mechanism of Reduced Sintering Temperature of Al2O3–ZrO2 Nanocomposites Obtained by Microwave Hydrothermal Synthesis. Materials. 2018; 11(5):829.Chicago/Turabian Style
Koltsov, Iwona; Smalc-Koziorowska, Julita; Prześniak-Welenc, Marta; Małysa, Maria; Kimmel, Giora; McGlynn, Jessica; Ganin, Alexey; Stelmakh, Swietlana. 2018. "Mechanism of Reduced Sintering Temperature of Al2O3–ZrO2 Nanocomposites Obtained by Microwave Hydrothermal Synthesis." Materials 11, no. 5: 829.
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