Study on nanometer s-cobalt powder prepared by precipitation-hydrogen reduction in Co(II)-(NH_4)_2CO_3-H_2O system

摘要

Nanometer e-cobalt powder was fabricated by liquid-phase deposition-hydrogen reduction method. Dif-ferent precipitators were mixed with CoCl_2 solution respectively to prepare the precursor of Co_2(OH)_2CO_3 precipitation. Then the precipitation was washed, dried and hydrogen-reduced. Nanometer s-cobalt pow-der was obtained. The characteristics of the precursor and cobalt powder from different precipitating agent were analyzed and compared. The precipitation mechanism of the Co-based precursor in Co(II)-(NH_2)_2CO_3-H_2O system was discussed and summarized for the first time. The results show that the use of (NH_4)2CO_3 as precipitating agent is conducive to preparing fine and uniform precursor and cobalt powder. Processing parameters of hydrogen reduction exert a great influence on particle size of cobalt powder: the lower reduction temperature, the finer the particle size, but the higher the oxygen content of cobalt powder. Close-packed hexagonal s-Co powder with BET particle size less than 100 nm and oxy-gen content lower than 0.8 wt.% can be fabricated when reduction process was carried out at 400 °C. Moreover, the nanometer cobalt powders had spherical shape with good dispersibility.