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This study of the thermal decomposition kinetics of various average diameter nano-particles of calcium carbonate by means
of TG-DTA (thermogravimetry and differential thermal analysis) showed that the thermal decomposition kinetic mechanisms of
the same crystal type of calcium carbonate samples do not vary with decreasing of their average diameters; their pseudo-active
energyE
a; and that the top-temperature of decompositionT
p decreases gently in the scope of micron-sized diameter, but decreases sharply when the average diameter decreases from micron
region to nanometer region. The extraordinary properties of nano-particles were explored by comparing the varying regularity
of the mechanisms and kinetic parameters of the solid-phase reactions as well as their structural characterization with the
variation of average diameters of particles. These show that the aggregation, surface effect as well as internal aberrance
and stress of the nano-particles are the main reason causing bothE
a andT
p to decline sharply with the decrease of the average diameter of nano-particles.
Project supported by Guizhou Province Natural Science Foundation of China 相似文献
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INTRODUCTIONTherearefewofquantitativethermalanalysis(TA)investigations (Mulokozi,1992 )ofthegoverningrelationsbetweentheparametersofsolidphasereactionkineticsandtheaveragedi ametersofultrafinecalciumcarbonateandtheeffectsoffineparticlesontheirsolidphasere… 相似文献
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以内容为依托的理工科大学学术英语类课程以可理解的语言输入为教学手段,让学生既可以学习目的语言,又可以掌握学科知识。是将外语学习同内容学习结合起来的一种有效教学途径。国外针对这类课程的研究已开展多年,并取得了丰硕成果;而国内的研究则呈方兴未艾之势。国内的学者们也已意识到这类课程在我国理工科大学的开设顺应了大学英语教学改革的潮流,凸显了理工科大学生英语学习实用性的要求,将是对现有大学英语课程的有益补充,是大学通用英语教学向专业英语教学转变的过渡阶段。但国内真正具有实证性和开拓性的研究还有待继续深入。 相似文献
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