TiH_2脱氢规律与动力学计算

Thermal dehydrogenation behavior of TiH_2 and its dynamics calculation

TiH2常用作泡沫铝和粉末冶金制品的原料,控制其脱氢进度是生产中的关键步骤。利用XRD与DSC技术得到TiH2在氩气气氛中加热分解分3步完成,即TiH2→TiH1.5→Ti(固溶)→Ti。用单个扫描速率法和多重扫描速率法对DSC/TG数据进行计算,得到TiH2→TiH1.5的机理模式为球形对称边界反应,TiH1.5→Ti(固溶)的机理模式为化学反应,Ti(固溶)→Ti转变机理为三维球形对称扩散,3步转变的活化能分别为240、190和145 kJ/mol。因此,与单个扫描速率法相比,采用多重扫描速率法研究TiH2热分解,其结果与实际情况更接近。

Thermal dehydrogenation of TiH2 is a key step in the manufacture of foamed aluminum and other powders metallurgy （PM） parts when TiH2 powders are used as raw materials. With the test results of TiH2 thermal decomposition in argon atmosphere obtained by XRD and DSC techniques, its thermal dehydrogenation process can be divided into three steps, namely, TiH2 → TiH1.5 → Ti （with H in solution） → Ti. The thermal decomposition dynamics calculation of titanium hydrides was conducted by both individual scanning rate method and multiple scanning rate method. It is found that the transformation mechanism of TiH2 → TiH1.5, TiH1.5 → Ti （with H in solution） and Ti（with H in solution） → Ti are of spherical symmetric boundary reaction, chemical reaction and three-dimensional spherical symmetric diffusion, respectively, and their opposite dehydrogenation activation energies are 240, 190 and 145 kJ/mol, separately. Multiple scanning method was finally proposed in dynamics analysis of TiH2 thermal decomposition for more reasonable results fitted with reality in comparison with individually scanning rate method.