Controllable preparation and regulation mechanism of ultrafine spherical cobalt powder
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摘要: 以CoCl2·6H2O和NH4HCO3为原料，通过液相沉淀法制备出粒径细小、均匀可控的CoCO3前驱体，再经过煅烧-氢还原制备出超细类球形钴粉。通过扫描电子显微镜（SEM）、X射线衍射仪（XRD）和同步热分析（DSC-TG）分别表征各阶段所获得粉体的微观形貌，物相和失重比。分析液相沉淀法中搅拌时间、反应温度对CoCO3粒径及形貌的影响规律；分析氢还原工艺对还原产物物相，粒径及形貌的影响规律。结果表明，随着搅拌时间的延长、反应温度的升高会提高CoCO3的形核率，进而CoCO3平均粒径减小；在搅拌时间为45 min，反应温度为25 ℃时，制备出粒径均匀，球形度高，平均粒径为0.96 μm的CoCO3。在氢还原Co3O4过程中，随着氢还原时间的延长、温度的升高，钴粉粒径变大；当氢还原温度为400 ℃，时间为45 min时，钴粉平均粒径最小为0.4 μm。
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Abstract: Using CoCl2·6H2O and NH4HCO3 as raw materials, the CoCO3 precursor with fine, uniform and controllable particle size was prepared by liquid-phase precipitation method, and then ultrafine spherical cobalt powder was prepared by calcination-hydrogen reduction. Scanning electron microscope (SEM), X-ray diffractometer (XRD) and simultaneous thermal analysis (DSC-TG) were used to characterize the microscopic morphology, phase and weight loss ratio of the powder obtained at each stage, respectively. The influence of stirring time and reaction temperature on the particle size and morphology of CoCO3 in the liquid-phase precipitation method was analyzed; the influence of hydrogen reduction process on the phase, particle size and morphology of the reduction product was analyzed. The results show that the nucleation rate of CoCO3 will increase with the increase of stirring time and reaction temperature, and then the average particle size of CoCO3 will decrease. CoCO3 with high sphericity and an average particle size of 0.96 μm. In the process of hydrogen reduction of Co3O4, with the prolongation of hydrogen reduction time and the increase of temperature, the particle size of cobalt powder becomes larger; when the hydrogen reduction temperature is 400 ℃ and the time is 45 min, the average particle size of cobalt -
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