镁在水蒸气中高温氧化的动力学特性

Kinetics of High Temperature Oxidation of Magnesium in Steam

对镁在水蒸气中着火前的高温氧化特性和机理进行了研究.发现水蒸气中镁的高温氧化反应可以分为3个阶段:在400℃前基本不发生反应;高于400℃后为高温氧化阶段,属于表面反应;在大约500℃后可能出现气相反应,继续加热可能出现着火和燃烧.通过实验和理论分析研究了内、外扩散速率和化学反应速率量级,明确了化学反应速率是该过程的速率控制步骤.在对镁高温氧化模型进行分析的基础上,计算了镁在水蒸气中高温氧化阶段的动力学参数.

The oxidation characteristics and mechanism of magnesium in steam were studied.The oxidation process was divided into three stages.Oxidation below 400,℃ can be neglected;high temperature surface oxidation occurs within the temperature range of 400—500,℃;when the metal temperature is above 500,℃,gas phase reaction may begin.Further heated,magnesium may be ignited in steam.The magnitude of inner diffusion rate,external diffusion rate and chemical reaction rate was analyzed experimentally and theoretically,which shows that chemical reaction rate is the control step of this process.After model discussion,the kinetic parameters of high temperature oxidation stage were calculated.