Li Yungang

Electrochemical Behavior of Tungsten in the (NaCl-KCl-NaF-Na2WO4) Molten Salt

Abstract The electrochemical reaction mechanism and the electrocrystallization process of tungsten in the NaCl-KCl-NaF-Na2WO4 molten salt were investigated at 973 K (700 °C) by means of cyclic voltammetry, chronopotentiometry and chronoamperometry technique. The results show that the electrochemical reaction process of tungsten is a quasi-reversible process mix-controlled by ion diffusion rate and electron transport rate; the electrocrystallization process of tungsten is an instantaneous hemispheroid three-dimensional nucleation process; the tungsten ion diffusion coefficient is 2.543×10−5cm·s−1 at the experimental condition of XNaCl:XKCl:XNaF: XNa2WO4= 2:2:1:0.01.

ZnO-TiO 2 体系的固相合成与表征

以分析纯ZnO和TiO2粉体为原料，直接固相法制备钛酸锌粉体.利用X射线衍射（XRD）、扫描电镜（SEM）对粉体物相、形貌进行表征，采用热重-差热（TG-DTA）研究固相反应机理. 结果表明：氧化物粉体最低反应温度为800 ℃，升高反应温度有利于Zn2TiO4相的生成，延长反应时间有利于六方相ZnTiO3生成. 在800~900 ℃保温4 h获得平均粒径为0.3~0.5 μm的球形钛酸锌粉体，该晶体生长过程为扩散机制控制，调整温度对产物形貌影响不大.