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Cobalt metal powder was prepared from cobalt tetroxide new technology

Author: ZuoQin
Tutor: YeHongQi
School: Central South University
Course: Chemical processes
Keywords: Cobalt powder Cobalt oxalate Solid-liquid reaction Cobalt tetroxide The morphology and particle size control
CLC: TQ138.12
Type: Master's thesis
Year: 2011
Downloads: 80
Quote: 0
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Abstract


Preparation of the tetroxide cobalt powder mostly the precursor cobalt oxalate thermal decomposition method, the conventional process of preparation of cobalt oxalate precursor is soluble cobalt salt and oxalic acid or ammonium oxalate liquid phase precipitation reaction. The particle size and morphology of the precursor oxalic drill directly affect the cobalt tetroxide performance of the final product. Free energy and its influencing factors on the basis of analysis of the standard metal cobalt powder and acid react proposed a new method of cobalt metal powder was prepared from the precursor cobalt oxalate, developed the synthesis of metal cobalt powder with oxalic acid reaction cobalt oxalate precursor, and then prepared by thermal decomposition of the precursor tetroxide drilling new technology. Obtained new technology cobalt oxalate precursor and oxide three cobalt powders using X-ray diffraction, scanning electric microscopy, laser particle size analyzer, thermogravimetric - differential thermal analysis instrument such as detection means were used to characterize and explore the powder formation process and its impact factors. The research results show that using the solid-liquid reaction of cobalt metal powder and oxalic acicular cobalt oxalate powder, and the diameter and aspect ratio of the the oxalic diamond powder can be regulated by external conditions change. Constant particle size shrinking core model to describe the mass transfer in the solid-liquid reaction of cobalt powder, the mass transfer process is controlled by chemical reaction, the activation energy Ea = 26.335KJ/mol. Inspect the metal drill powder reacted with oxalic acid to obtain acicular cobalt oxalate Preparation process parameters found that an aspect ratio and the reaction temperature of the cobalt oxalate, cobalt powder concentration, stirring rate, and other parameters, as well as a strong inorganic acid such as nitric acid, hydrochloric add not closely related, wherein the nitric acid is added acicular cobalt oxalate crystal aspect ratio can be increased, and hydrochloric acid was added then the aspect ratio decreases. The reaction temperature of 50 ° C, oxalic acid, and cobalt powder metering 2.5:1 ratio (molar ratio), nitric acid dosage conditions of 0.05 mol / L, the aspect ratio of needle-like cobalt oxalate powder 46. When the temperature is higher than 287 ℃, the thermal decomposition of cobalt oxalate powder can be the tetroxide cobalt powder. Calcination temperature and insulation time the formation of oxide three cobalt powder of greater impact in the temperature at 400 ℃ or 600 ° C, 1h or 3h calcining time, get tetroxide three cobalt powder can inherit the morphology of the precursor temperature higher than 600 ℃ or holding time of more than 3h will lead to the final product cobalt tetroxide powder produced severe sintering phenomena.

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CLC: > Industrial Technology > Chemical Industry > Inorganic compounds, the chemical industry of the metal elements > Inorganic compounds of the first the Ⅷ family metal elements > Inorganic compounds of iron elements > Cobalt inorganic compound
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