Abstract: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 1.128 μm, 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 29.665 μm, 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.

Key words: tungsten particles; salt-assisted hydrogen reduction; chlorine salt; morphology; size; controllable synthesis