排序方式: 共有42条查询结果,搜索用时 0 毫秒
41.
Starch - A suitable fuel in new low-temperature combustion-based synthesis of zinc aluminate oxides 总被引:1,自引:0,他引:1
Starch has been tested as single-fuel and in a two-fuel mixture, together with N-methylurea, in a new combustion-based synthesis of zinc aluminate oxides, using different fuel compositions and equivalence ratios Φe (Φe = fuel/oxidant). The combustion process has been analyzed by simultaneous thermal analysis. The corresponding oxides were characterized by X-ray diffraction analysis, UV-Vis spectroscopy, scanning electron microscopy and BET investigations. Crystal structures were refined by Rietveld method. The morphology, specific surface area and optical properties of the obtained zinc aluminate have proved to be strongly dependent on the fuel nature and composition. The lowest crystallite size (131 Å) is achieved for the oxide generated from the starch-based precursor, while the highest surface area (20.69 m2/g) has been obtained for a 3:1 N-methylurea/starch fuel composition. The non-zero value for microstrain has indicated spinelic defects in the starch-fuel corresponding oxide. UV-Vis spectroscopic analysis have confirmed the intrinsic properties of the resulted mixed metal oxide, but also shows the presence of a certain disorder degree for all the other samples. The superior values of the band gap (4.2-4.7 eV) for the obtained oxides relative to the bulk case (3.8 eV) are the result of the nanometric dimensions of the particles. 相似文献
42.
Raluca Dumitru Oana Carp P. Budrugeac M. Niculescu E. Segal 《Journal of Thermal Analysis and Calorimetry》2011,103(2):591-596
The authors present their results concerning the decomposition in air of the homopolynuclear coordination compound [CoC2O4·2.5H2O]
n
. In the temperature range 20–300 °C, the heating curves TG, DTG and DTA allowed to evidence three decomposition steps. The
kinetic analysis was performed on the second step which proved to be the only workable one. The application of nonlinear regression
procedure shows that this is a complex process consisting in three successive steps. The checking of the mechanism and corresponding
kinetic parameters for quasi-isothermal data (T = 150 °C) shows that the obtained results could be used for prediction of the thermal behaviour of the investigated compound
in both isothermal and non-isothermal conditions. 相似文献