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Influence of mechanochemical activation on the sintering of cordierite ceramics in the presence of Bi₂O₃ as a functional additive

Obradović, N., Đorđević, N., Filipović, S., Nikolić, N., Kosanović, D., Mitrić, M., Marković, S., Pavlović, V.
Powder technology 2012 v.218 pp. 157-161
X-ray diffraction, ceramics, mechanical properties, particle size, powders, scanning electron microscopy, temperature
Due to its outstanding electrical characteristics, such as the low temperature expansion coefficient, low dielectric constant and good mechanical properties, cordierite, 2MgO⋅2Al₂O₃⋅5SiO₂, is a very attractive high-temperature ceramic material. In order to accelerate the process of sintering, 2.50 mass% Bi₂O₃ has been added to the starting mixtures. Liquid phase sintering caused by the presence of bismuth-oxide lowers the temperature of cordierite formation. The mechanical activation of the starting mixtures (0–56min in vibro-mill) additionally lowers sintering temperatures. The sintering process was performed at 1200, 1300, 1350 and 1400°C, for 2h. The particle size analysis (PSA) was employed in order to determine the changes in the particle size of the mechanically treated powders. The phase composition of the starting powders and sintered materials was analyzed by the X-ray diffraction method. Furthermore, scanning electron microscopy (SEM) was used in the analysis of the powder morphology.