Influence of chemical composition on sintering ability of ZTA ceramics consolidated from freeze dried granules |
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Authors: | Ibram Ganesh G SundararajanSM Olhero JMF Ferreira |
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Affiliation: | a Centre for Advanced Ceramics, International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad 500005, A.P., India b Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro P-3810193, Portugal |
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Abstract: | Dense zirconia-toughened alumina (ZTA) ceramic composites with ZrO2 = 0, 5, 10, 15, 20, 30, 60 and 100 wt.% have been prepared by sintering green compacts obtained by dry powder pressing of freeze dried granules consisting of α-alumina and a yttria partially stabilized zirconia (YPSZ) at various temperatures ranging from 1450 to 1650 °C for 1-2 h. The characteristics of sintered products were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), Archimedes principle, Vickers indentation method and by 3-point bend test. Characterization results revealed that adding YPSZ increased the 3-point bend (flexural) strength, fracture toughness and homogeneity of the microstructure, but slightly decreased the hardness and the sintering ability of alumina. A 20 wt.% YPSZ was sufficient to increase the fracture toughness and flexural strength of specimens sintered for 2 h at 1600 °C from 2.5 to 4.6 MPa m1/2 and 150 to 400 MPa, respectively. The XRD results revealed that there is no solid-solution formation between zirconia and alumina constituents of ZTA ceramic composites upon sintering. |
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Keywords: | C Hardness C Strength ZTA ceramics Freeze granulation Fracture toughness |
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