微米锆粉的热氧化过程研究

Thermal Oxidation Process of Micron Zirconium Powder

为探究微米锆粉的热氧化过程,进行锆粉氧化反应动力学分析,通过激光粒度分析、扫描电子显微镜(SEM)和X射线衍射仪(XRD)等方法对所研究锆粉颗粒的粒径分布、微观形貌、元素含量以及物相特征进行了研究。通过热重分析法(TG)和差示扫描量热法(DSC)开展了不同升温速率的氧化过程研究,得到不同升温速率下锆粉氧化的DSC-TG曲线,进一步分析得到锆粉热氧化的动力学参数以及反应模型。结果表明,锆粉样品的粒径主要分布在15~46μm,颗粒形状不规则,且主要包含Zr元素,锆粉颗粒主要物相为金属Zr;锆粉氧化过程可以分为初始氧化,加速氧化、剧烈氧化和反应平衡四个阶段;锆粉的非等温氧化过程符合随机成核和随后生长模型函数,其积分表达式为G(α)=[-ln(1-α)]52。因此微米锆粉热氧化反应动力学的活化能Ea为175.83 kJ·mol^-1,指前因子A=1.91×10^8 s^-1,反应速率常数k=1.91×10^8 exp(-2.1×10^4/T)。

In order to investigate the process and kinetics for the thermal oxidation of micron zirconium powders,the particle size distribution,micromorphology,elemental content and phase characteristics of the zirconium powders were studied by laser particle size analysis,scanning electron microscopy(SEM)and X-ray diffraction(XRD).The oxidation process at differ-ent heating rates was studied by thermogravimetry and differential scanning calorimetry(TG-DSC).The kinetic parameters and reaction model were obtained.The particle size of zirconium powders was in the range of 15-46μm,with irregular particles.The main phase of zirconium powder particles was metallic Zr.The oxidation process of zirconium powder can be divided into the four stages including initial oxidation,accelerated oxidation,vigorous oxidation and reaction equilibrium.The non-isothermal oxidation process followed the random nucleation and subsequent growth model function with the inte-gral expression G(α)=[-ln(1-α)]^5/2.Further,the activation energy Ea and pre-exponential factor A for the thermal oxidation reaction was 175.83 kJ·mol^-1 and 1.91×10^8 s^-1,respectively.The reaction rate constant k=1.91×10^8 exp(-2.1×10^4/T).