用热重分析法研究阿尔及利亚Tamazarte高岭土的热分解动力学

摘要

The decomposition kinetics of Algerian Tamazarte kaolinite (TK) was investigated using thermogravimetric analysis (TG).Differential thermal analysis (DTA) and TG experiments were carried out between room temperature and 1400 ℃,at different heating rates from 10 to 40 ℃/min.The activation energies,measured by DTG from isothermal treatments using Johnson-Mehl-Avrami (JMA) and Ligero methods and by non-isothermal treatments using Ozawa,Boswell and Kissinger methods,were around 151 and 144 kJ/mol,respectively.The Avrami parameter of growth morphology (indicating the crystallization mode) was found to be around 1.57 using non-isothermal treatments;however,when using isothermal treatments it is found to be equal to 1.35.The numerical factor,which depends on the dimensionality of crystal growth,is found to be 1.53 using Matusita equation.The frequency factor calculated by the isothermal treatment is equal to 1.55× 107 s-1.The results show that the bulk nucleation is followed by three-dimensional growth of metakaolinite with polyhedron-like morphology controlled by diffusion from a constant number of nuclei.%采用热重分析法(TG)和研究阿尔及利亚Tamazarte高岭土的热分解动力学.差热分析(DTA)和TG实验在室温～1400℃下进行,加热速率为10～40℃/min.采用JMA和Ligero法由等温处理测得的活化能,以及采用OFW和KAS法由非等温处理测得的活化能,分别约为151和144 kJ/mol.采用非等温处理确定的生长形貌Avrami参数约为1.57,而采用等温处理时该值约为1.35.数值因数与晶体生长的维度有关,采用Matusita方程确定的值为1.53.采用等温处理时,计算得到的频率因子为1.55×107 s-1.结果表明,块体形核之后伴随偏高岭土的三维生长,偏高岭土具有受扩散控制的多面体结构,以一定数量的晶核开始生长.