盐助还原法对金属钨颗粒形貌和尺寸的影响

Effect of salt-assisted reduction method on morphologies and size of metallic tungsten particles

提出一种利用盐助氢气还原制备形状和尺寸可控钨颗粒的简单方法,并通过调节氯盐添加量和温度制备形状和尺寸可控的钨颗粒。加入盐添加剂后,最终产物的分散性得到明显改善,颗粒生长更加充分。其中,NaCl与LiCl的作用尤为显著。在1038 K时添加0.1%NaCl(质量分数)和0.1%LiCl(质量分数)的钨颗粒平均粒径分别为0.924和1.128μm。随着温度和氯盐添加量的增加,生成的钨颗粒的分散性变好,小颗粒的粒径增大,形状由球形变为多面体。特别是在1349 K下,氯盐的加入使钨颗粒的粒径显著增大,添加1%NaCl(质量分数)和1%LiCl(质量分数)钨颗粒的平均粒径分别达到21.367和29.665μm。基于传统假晶转变和化学气相传输机理,还详细探讨添加盐对反应机理的影响。

A simple method was proposed to produce tungsten(W)particles with controllable shape and size by employing the salt-assisted hydrogen reduction.W particles with controlled shape and size were prepared by adjusting the amount of chlorine salts and the temperature.After adding salt additives,the dispersibility of final particles was obviously improved and more adequate growth of particles was obtained.It was found that the effect of NaCl and LiCl is particularly significant.The average sizes of the obtained W particles at 1038 K after adding 0.1 wt.%NaCl and 0.1 wt.%LiCl were 0.924 and 1.128μm,respectively.With the increase of temperature and amount of chlorine salts,the dispersity of the produced W particles became much better,the size of W sub-particles was increased,and the shape of W sub-particles was changed from spherical to polyhedral.At 1349 K,the addition of chlorine salts even multiplied the particle size,and the average sizes of W particles with 1 wt.%NaCl and 1 wt.%LiCl were raised up to 21.367 and 29.665μm,respectively.Based on the conventional pseudomorphic transformation and chemical vapor transport mechanisms,the effects of adding salts on the reaction mechanism were investigated in detail as well.