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The effect of the particle shape and structure on the flowability of electrolytic copper powder. I. Modeling of a representative powder particle
KONSTANTIN I. POPOV,SNEZANA B. KRSTIC,MILUTIN C. OBRADOVIC,MIOMIR G. PAVLOVIC
Journal of the Serbian Chemical Society , 2003,
Abstract: One of the most important properties of copper powder is its flowability 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 effect of the particle shape and structure on the flowability of electrolytic copper powder. III. A model of the surface of a representative particle of flowing copper powder electrodeposited by reversing current
KONSTANTIN I. POPOV,SNEZANA B. KRSTIC,MILUTIN C. OBRADOVIC,MIOMIR G. PAVLOVIC
Journal of the Serbian Chemical Society , 2004,
Abstract: 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 effect of the particle shape and structure on the flowability of electrolytic copper powder. IV. The internal structure of the powder particles
KONSTANTIN I. POPOV,SNEZANA B. KRSTIC,MIOMIR G. PAVLOVIC,LJUBICA J. PAVLOVIC
Journal of the Serbian Chemical Society , 2004,
Abstract: The structure of powder particles was 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.
The effect of particle structure on apparent density of electrolytic copper powder
M. G. PAVLOVIC,LJ. J. PAVLOVIC,E. R. IVANOVIC,V. RADMILOVIC
Journal of the Serbian Chemical Society , 2001,
Abstract: The quantitative microstructural analysis and the sieve analysis of copper powder as well as the scanning electron microscopy analysis of the copper powders particles were performed. It was found that the structure of the copper powder particles determines the apparent density of copper powder. The powder particles from the same fractions of different powders occupy approximately the same volume, but the structure of metallic copper is very different. This causes the difference in apparent densities of copper powder obtained under different conditions. The more dendritic is the structure of powder particles the smaller is the apparent density of copper powder.
The effect of reversing current deposition on the apparent density of electrolytic copper powder
K. I. POPOV,LJ. J. POPOVIC,E. R. IVANOVIC,V. RADMILOVIC
Journal of the Serbian Chemical Society , 2002,
Abstract: 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.
Preparation and Characterization of Near Nano Copper Powder by Electrolytic Route  [PDF]
Akansha Sengar, Prathvi Raj Soni
International Journal of Nonferrous Metallurgy (IJNM) , 2014, DOI: 10.4236/ijnm.2014.34005
Abstract:

For the preparation of copper nanoparticles several methods, i.e., thermal reduction, mechanical attrition, chemical reduction metal vapour synthesis, radiation methods, laser ablation and micro emulsion techniques were developed in the past. Electrolytic deposition is one of the most suitable, simplest and low cost methods which are used for wide range of materials. In the present investigations, efforts were put to produce copper nano powder using electrolytic technique. It could be possible to obtain near nano copper powder of 258 nm size using high cathode current density of 1100 A/m2 in sulphate bath. The specific surface area and shape of the particles were found to be 23.2 m2/g and irregular, respectively.

Experimental Investigation on Flowability and Compaction Behavior of Spray Granulated Submicron Alumina Granules  [PDF]
Abhisek Choudhary,Pandu Ramavath,Papiya Biswas,Nukala Ravi,Roy Johnson
ISRN Ceramics , 2013, DOI: 10.1155/2013/264194
Abstract: Aqueous slurry with various solid loadings (up to 40?wt%) of alumina powder (D50?=?300?nm) with suitable rheological properties were spray dried into granules. Solid loading and feed rate of the slurry are found to have a prominent effect on the shape and size distribution of granules. Powder flow measurements exhibited a cohesive index of 28.45 signifying an extremely cohesive flow due to high surface area and irregular morphology. Finer sizes though it offers high geometrical surface area it leads to more surface contacts and hence, high interparticle friction. Spherical morphology achieved through optimum spray drying parameters significantly reduced the cohesive index to 6.45 indicating free flow behavior. Compaction studies of the spray-dried granules and corresponding plot of relative density versus compaction pressure revealed an agglomerate strength of 500?MPa followed by a plateau-like behavior reaching a maximum in the relative density of 59%-60% of the theoretical values. 1. Introduction Flow properties of the powders are dictated by the collective forces acting on individual particle such as vander waals and electrostatic forces, surface tension, interlocking as well as friction. Compaction process of ceramic powders basically involves die filing and particle rearrangement under applied stress followed by brittle fracture and bonding between the particles [1–6]. Further, the removal of the applied pressure and ejection of the compact completes the compaction process. Flow variables such as energy required to ensure an acceptable flow, sensitivity to flow rate as consequence of the previous collective forces, and distribution of the particles under applied stress play a major role in determining the quality of the formed compact. Flow properties of the fluids and pastes are characterized in terms of their rheological properties but similar treatment cannot be applied to the powders. Several experimental techniques have been developed to determine the flow behaviors of the powders. The flow properties are generally characterized by physical measures such as angle of repose, flow and shear based methods and even correlated with tap density and green strength of the compact [7–9]. Flowability of powder is a complex parameter that cannot be described with a single number and there is no universal model in existence to predict powder flow behaviour in every situation. Particulate flow characteristics are complex and flow properties are a combined effect of physical and environmental variables. Hence, flowability is a combination of physical
Relationship between particle size and manufacturing processing and sintered characteristics of iron powders
Sánchez,F.; Bolarín,A. M.; Molera,P.; Mendoza,J. E.; Ocampo,M.;
Revista Latinoamericana de Metalurgia y Materiales , 2003,
Abstract: abstract the effect of particle size distribution on physical properties of powder mixtures, of green compacts and of sintered samples has been studied. in the case of powder mixtures, the evaluated properties were flowability, apparent density, specific surface and compressibility. in green compacts porosity, roughness and green strength were evaluated, and in sintered samples grain size and transverse rupture strength were measured. in order to obtain samples with different average particle size, water atomized iron powders were sieved and separating it with sieves ranging from +44 to -150 m m. flowability and compressibility decrease as average particle size does. on the opposite side, green strength and transverse rupture strength (trs) increase as particle size diminishes. these effects were associated with changes in morphology and specific surface of the studied powder mixtures. mathematical expressions relating average particle size with green strength, roughness and ultimate tensile strength were deduced from the experimental results. the results show that an appropriate selection of average particle size for the preparation of the powder mixture is useful in order to obtain samples with suitable physical properties.
The respresentative particle of copper powder and branching of copper dendrites
K. I. POPOV,N. D. NIKOLIC,Z. RAKOCEVIC
Journal of the Serbian Chemical Society , 2002,
Abstract: Electrochemically deposited copper powders, which are formed of particles of different size and morphology, are characterized by some properties like specific surface and apparent density. A procedure of the determination of a representative powder particle, exhibiting the same values of specific surface and apparent density as the powder is proposed. The proposed procedure also permints an explanation of the branching of copper dendrites.
Lactose Engineering for Better Performance in Dry Powder Inhalers
Yahya Rahimpour,Hamed Hamishehkar
Advanced Pharmaceutical Bulletin , 2012,
Abstract: Dry powder inhaler (DPI) is generally formulated as a powder mixture of coarse carrier particles and micronized drug with aerodynamic diameters of 1-5 μm. Carrier particles are used to improve drug particle flowability, thus improving dosing accuracy, minimizing the dose variability compared with drug alone and making them easier to handle during manufacturing operations. Lactose is the most common and frequently used carrier in DPIs formulations and nowadays various inhalation grades of lactose with different physico-chemical properties are available on the market. Therefore, the purpose of this manuscript is to review evolution of lactose as a carrier in inhalable formulations, their production and the impact of its physico-chemical properties on drug dispersion. This review offers a perspective on the current reported studies to modify lactose for better performance in DPIs.
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