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Synthesis, Densification and Characterization of Nanosized Oxide Ceramic Powders with Eutectic Compositions by Heating of Alcohol-Aqueous Salt Solutions
J.-H. Ouyang, Y.-H. Ma, A. Henniche, B. Wang, Z.-G. Wang, Y.-J. Wang
School of Materials Science and Engineering, Harbin Institute of Technology, 92 Westdazhi Street, Harbin 150001, China
received October 29, 2016, received in revised form December 3, 2016, accepted January 13, 2017
Vol. 8, No. 1, Pages 81-90 DOI: 10.4416/JCST2016-00097
Abstract
Nanosized spherical powders of Al2O3-ZrO2 (Y2O3) and Al2O3-SmAlO3 with eutectic compositions have been synthesized with a facile and novel method involving the heating of aqueous salt solutions with an alcohol-water mixture as the solvent. The kind and concentration of aqueous salt solutions have a significant influence on the precipitation and morphologies of the resulting powders. Nanoscale particulates with a narrow size distribution were successfully obtained. The amorphous powders are crystallized to a mixture of t-ZrO2 phase and α-Al2O3 phase at a calcination temperature of 1250 °C. Al2O3-ZrO2 (Y2O3) powders exhibit an average particle size of 200 nm after calcination. However, fine Al2O3-SmAlO3 nano-powders with an average size of 40 nm were synthesized after calcination at 1300 °C in which the resulting precipitates are crystallized to a mixture of α-Al2O3 and orthorhombic SmAlO3. These ceramic powders were densified by hot pressing to further evaluate their microstructure and mechanical properties. The as-sintered Al2O3-ZrO2 (Y2O3) ceramic consists of 42.8 wt% t-ZrO2 and 57.2 wt% α-Al2O3 with a relative density of 98.5 %, and has a flexural strength of 1363 MPa and fracture toughness of 10.01 MPa·m1/2, which is mainly attributed to phase transformation toughening of t-ZrO2 to m-ZrO2 during fracture. However, the Al2O3-SmAlO3 ceramic has a relative density of 99.2%, but flexural strength of just 529 MPa.
Keywords
Al2O3-ZrO2(Y2O3) ceramic, Al2O3-SmAlO3 ceramic, co-precipitation, microstructure morphology, mechanical properties
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Göller Verlag GmbH
