镁橄榄石合成反应动力学研究

以分析纯氧化镁、高纯熔融石英以及电熔镁砂颗粒为原料，研究了固相法合成镁橄榄石的反应动力学.利用X射线衍射和扫描电子显微镜等手段，研究了合成温度和保温时间对镁橄榄石生成速率的影响，分析了MgO与SiO2的反应机理.根据实验结果，建立了1100~1300℃下MgO与SiO2反应的动力学方程，并求出了表观反应活化能.研究结果表明，随着合成温度的提高和保温时间的延长，镁橄榄石生成率逐渐增加.在反应初期，MgO与SiO2反应生成了镁橄榄石和顽火辉石，在合成反应中后期时Mg2+通过产物层扩散而进一步反应，MgO与SiO2反应合成镁橄榄石的反应过程由Mg2+扩散所控制，反应的表观活化能为(220±20)kJ/mol.

Study on the Reaction Kinetics of Forsterite Synthesis

The reaction kinetics of forsterite synthesis was studied through solid-phase reaction by using analytically pure magnesium oxide, high purity fused silica and fused magnesia particles as main raw materials. The effects of the sintering temperature and holding time on the synthesis of forsterite were studied by X-ray diffraction analysis and scanning electron microscopy. The mechanism of reaction between MgO and SiO2 was discussed. The reaction kinetics equations of the reaction process between MgO and SiO2 in the range of 1100~1300°C were established, and the apparent reaction activation energy was obtained according to the experimental results. The results showed that forsterite synthesis rate gradually increases with the synthesis temperature and holding time increasing. Forsterite and enstatite are formed during the initial stage of synthesis reaction, and the reaction process of MgO and SiO2 is controlled by the Mg²⁺ diffusion. The apparent reaction activation energy is (220±20) kJ/mol.