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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
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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