矿物棉纤维的非等温析晶动力学研究

Non-isothermal crystallization kinetics of mineral wool fibers

  • 摘要: 利用差热分析仪和X射线衍射仪研究了矿物棉纤维的析晶行为.矿物棉纤维的差热曲线上存在两个重叠的析晶峰.X射线衍射结果和扫描电镜分析结果表明该矿物棉在高温下析出两个结晶相:钙镁黄长石和钙长石,前者的析晶温度范围为850~920℃,后者的析晶温度范围为880~1 010℃.利用Ozawa方程和修正的Kissinger方程分析了两个析晶相的析晶机理和析晶活化能.钙镁黄长石的Avrami指数n为0.682,属于表面析晶机理,与扫描电镜观察到的结果相吻合;扫描电镜观察到钙长石生长方式为三维生长方式;计算得到钙镁黄长石和钙长石的晶体生长活化能EG分别为248 kJ·mol-1和347 kJ·mol-1.

     

    Abstract: The crystallization behavior of mineral wool was investigated by means of differential thermal analysis(DTA) and X-ray diffraction(XRD).DTA curves reveal the presence of two overlap exothermic peaks and XRD results shows that two crystalline phases are separated out:one is akermanite-gehlenite(AlCa2Mg0.5O7Si1.5),which was crystallized between 850℃ and 920℃;the other is anorthite(CaAl2Si2O8),which was crystallized between 880℃ and 1010℃.The Ozawa method and the modified Kissinger method were used to analyze the crystallization mechanism and the activation energy of crystallization.For the crystalline of akermanite-gehlenite,the activation energy of crystallization and the Avrami exponent are 248kJ·mol-1 and 0.682 respectively,indicating surface crystallization;whereas for anorthite,the activation energy of crystallization is 347kJ·mol-1,revealing three-dimensionality of crystal growth according to the results of scanning electron microscopy(SEM).

     

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