The possibility of depositing copper powders with different apparent density by changing the shape of reversing current wave is shown. The morphology and crystallinity of powder particles can be varied considerably by changing shape of the reversing current wave and, hence, the apparent density of powders. The relation of apparent density with particle morphology and structure was illustrated.
One of the most important properties of copper powder is its flow ability which depends on the shape and the structure of the powder particles. A procedure for the determination of a representative powder particle permitting the free flow of copper powder is proposed.
The structure of the surface of copper powder particles is discussed and correlated with the lowest apparent density at which copper powder can still flow. It is shown that such structures can be easily obtained in the electrodeposition of powders in reversing current regimes.
The structure of powder particleswas analysed by considering their cross sections. It was shown that the structure of powder particles of nonsieved flowing powders is sufficiently dense to produce a continuous surface, which does not allow the particles to jam and hence permits the free flow of nonsieved powder. It was also shown that the representative powder particle the elementary cell of which can be presented by a 3D-cross, describes the properties of the powder relative to its flowability well.
An analysis of the effects of the shape, surface structure and size distribution of particles on the flow ability of the copper powder was performed. It is shown that the most important property of the particles of a powder, regarding the flow ability of the powder, is the surface structure of the particles.
In order to study the kinetics and mechanism of the reaction, laboratory leaching was carried out with industrially produced gibbsite γ-Al(OH)3 in aqueous solutions containing an excess of sodium hydroxide. The results obtained reaction temperature, duration and base concentration varied. The basic kinetic parameters were determined from: the reaction rate constant k=8.72·107 exp (-74990/RT) and the process activation energy in the range Ea=72.5-96.81 kJ/mol
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