Papers by Keyword: Crystalline Microstructure

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Authors: Marek Andrzej Kojdecki, Witold Mielcarek, Krystyna Prociów, Joanna Warycha
Abstract: Varistors obtained by sintering zinc oxide with additives were investigated. In this work the crystalline microstructure of ZnO varistor body is studied by X-ray diffraction method, before and after additional annealing. The crystalline microstructure is characterised by the prevalent crystallite shape, the volume-weighted crystallite size distribution, the second-order crystalline lattice strain distribution and the derivative quantities. The evolution of these characteristics, particularly of bimodal size distribution, elucidate some details of the formation of crystalline zinc oxide and provide additional arguments for explaining the change of the electric characteristics of varistors induced by annealing.
Authors: Feng Li, Xiang Dong Liu
Abstract: Using fly ash from the power plant and SiO2 as the main raw materials, glass-ceramic was prepared by melting method. By means of DSC, XRD and SEM, the crystallizations of CaO-Al2O3-SiO2 system glass-ceramic were studied. The results show that it is more and more difficult to crystallize as the content of SiO2 increases. When the content of SiO2 reaches to 41.5%, the crystal nucleus form in the form of shuttle shape, the crystals develop in the same direction for a certain zone. But the crystals develop into hexagon shape finally when they are heated for 1 h at 1100°Cafter nucleation at 780°C.The developed crystals are anorthite. The sizes of crystals are between 1- 1.5μm, their microhardness can reach HV804.
Authors: Marek Andrzej Kojdecki, Francisco Javier Seranno, José Vicente Clausell, Joaquín Bastida
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