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| The influence of reduction temperature and raw materials on the crystal form of cobalt powder |
| ZHU Zhijun1，WANG Chao′an2，QU Peng2 |
| （1. School of Physics and Materials Science，Nanchang University，Nanchang 330000，China； 2. Anhui Hanrui
New Material Co.，Ltd.，Chuzhou 239000，China） |
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Abstract The effects of reduction temperature and raw materials on the crystal form of cobalt powder were stud‐
ied through controlled variable experiments, and the corresponding internal mechanism was explored. Four cobalt
compounds, CoCO3、CoC2O4·2H2O、Co3O4(T) and Co3O4(C), were used as raw materials, and the hydrogen reduc‐
tion method was used to prepare cobalt powder at different temperatures. The raw materials were evenly placed in
a stainless steel boat, and then placed in a sliding rail tube furnace, and the furnace tube was purged with argon for
a period of time to exhaust the air. After that, hydrogen gas was continuously passed in, and the temperature was
raised to the reaction temperature at a fixed rate and kept for a period of time. After the reaction, continue to pass
hydrogen gas and cool down in the furnace to room temperature, to obtain the sample.The phase analysis of the
product was carried out by XRD, and then the data was processed and edited by Origin software. These data were
finally used for result analysis and conclusion output. With the increase of reaction temperature, the proportion of
FCC-Co in the product increases significantly. However, the components of the reduction products of different raw
materials at the same temperature are different, and the corresponding temperature-component curves are also
different.For example, at 480 ℃, the content of FCC-Co in three groups of reduction products all exceed 90%, of
which the content of Co
3O4(T) reduction product is the highest at 96.0%, and the content of FCC-Co in the corre‐
sponding products of CoC2O4·2H2O and Co3O4(C) are 94.8% and 93.3%, respectively . However, the FCC-Co
content in the CoCO
3 reduction product is only 70% at this time. The above-mentioned four kinds of raw materials
are subjected to hydrogen reduction experiments under the same process, and the crystal composition of the
obtained reduced cobalt powder is obviously different. By controlling the temperature and raw material, it is possible to directionally prepare cobalt powder with a specified crystal form composition. When cobalt powder is pre‐
pared by hydrogen reduction, multiple reactions often affect the crystal composition of the product. CoCO3 can
undergo“direct reduction reaction”and“decomposition-reduction reaction”, and CoC2O4?2H2O has“direct reduc‐
tion reaction”,“dehydration-decomposition reaction”and“dehydration decomposition reaction”, Co3O4(T) and
Co
3O4(C) only have“direct reduction reaction”, but they can also be subdivided into“CoO reduction reaction”and
“Co
2O3 reduction reaction”
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Received: 04 November 2021
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2022, Vol. 32 
