• The Korean Journal of Ceramics
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• v.6 no.1
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• pp.58-63
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• 2000

The preparation of Y-doped $SrZrO_3$powder by ultrasonic spray pyrolysis was investigated as a representative system, in order to produce fine, single phase multicomponent oxide powders. A precursor solution containing metal nitrates, citric acid and ethylene glycol was atomized glycol was atomized with an ultrasonic spray nozzle. Gel particles formed by organic functional groups were pyrolyzed and subsequently calcined at $800^{\circ}C$ to obtain well-crystallized, single perovskite phase. Most of large particles exhibited macroscopic pores and weak agglomeration between primary particles. However, strong agglomeration was observed in the surfaces of large particles. The effect of the microstructures of these particles on size reduction to submicron particles was described.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.36 no.2
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• pp.24-32
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• 2004

Toner used in xerographic printing process is hydrophobic powder with low surface energy. The toner ink film fused on paper surface can be efficiently detached from a fiber surface during pulping, but it does not fragment again into fine toner particles. Ink agglomerates that result have too large particle size to be deinked by flotation. The purpose of this study is to enhance toner agglomeration using 1-octadecanol for improving the toner removal by screening. The effect of pH, pulping temperature, and 1-octadecanol on toner agglomeration and removal by screening was investigated using image analysis methods. Results showed that the size of toner agglomerates increased substantially when pulping was carried out at high temperature under acidic condition. When toner agglomerates showed spherical shape, the particle removal efficiency of screening was improved.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.224-230
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• 1999

Agglomeration of colloidal alumina particles in a suspension is simulated. Particles in a suspension have potential energies between them and move to decrease the summation of all the potential energies between particles. The effects of various types of potential curves on particle agglomeration were checked. Strong short range attractive energy without repulsive energy barrier makes small strong clusters with disordered network structure but weak short-range force with big repulsive energy barrier makes big agglomerates with a close packing structure. As particles are agglomerated the potential energy with strong repulsive energy barrier between agglomerates gradually decreases the importance of the repulsive energy barrier and induces a different type of agglomeration behavior.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.257-259
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• 1999

A molding of roasted glutinous rice powder by pressurized steaming was investigated in terms of steaming pressure and powder size. Roasted glutinous rice powders of $80{\sim}115,\;115{\sim}170,\;170{\sim}250$, and 250

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.654-655
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• 2006

This is about the effects deoxidization, carbonization and alloying preparation on fine grain W, WC, and grade YG8 powder reduced by "yellow tungsten oxide" and "blue tungsten oxide". The result indicates that yellow tungsten has single composition and blue tungsten oxide has complex composition. With this feature, yellow tungsten oxide got better uniformity and concentration distribution on fine particle size W and WC powder than blue tungsten oxide's. The grade alloy YG8 that made of this W or WC powder has uniform alloy construction, concentrated WC grain distribution and better alloy properties.

• Journal of Powder Materials
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• v.6 no.3
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• pp.238-245
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• 1999

The preparation of $n-TiO_2$ powder by the Chemical Vapor Synthesis process (CVS) was studied using the liquid metal organic precursor (TTIP). The residence time and the collection methods were considered as main processing variables through the experiments. The CVS equipment consisted of a micropump and a flashvaporizer, a tube furnace and a tubular collection device. The synthesis was performed at $1000^{\circ}C$ with various sets of collection zone. The residence time and the total system pressure were controlled in the range of 3~20 ms and 10 mbar, respectively. Nitrogen adsorption, X-ray diffraction and electron microscopy were used to determine particle size, specific surface area and crystallographic structure. The grain size of the as-prepared $n-TiO_2$ powder was in the range of 2~8 nm for all synthesis parameters and the powder exhibited only little agglomeration. The relationship between particle characteristics and the processing variables is reviewed based on simple growth model.

• Korean Journal of Metals and Materials
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• v.48 no.4
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• pp.326-334
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• 2010

Porous and net-shaped tantalum powder for a capacitor was formulated in a SHS (self-propagating high-temperature synthesis) process. However, this powder, which has weak strength among its particles and low flow ability, cannot be used for a capacitor. Therefore, this powder was sintered in a high-vacuum furnace to increase agglomeration to improve the flow ability, bonding strength among the particles, and shrinkage during pellet sintering. Finally, it was deoxidated with 2 wt% Mg powder to remove the increased surface oxygen that arose during the sintering process. The final product was analyzed in terms of its chemical and physical properties and was compared with a commercial powder used by a capacitor manufacturer.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.63-68
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• 2016

$Li_4Ti_5O_{12}$ is prepared through a solid-state reaction between anatase $TiO_2$ and $Li_2CO_3$ for the negative electrode active materials in quick-charging lithium-ion batteries. The small amount of carbon black (0, 0.5, 1.0, and 3.0 wt%) is added for the reduction of powder agglomeration during heat-treatment. As the amount of the added carbon black increases, the tap density of $Li_4Ti_5O_{12}$ powder gradually decreases. Furthermore, the $Li_4Ti_5O_{12}$ powder prepared with 1.0 wt% of carbon black shows the highest sieved fraction at the powder classification by 325 mesh standard sieve. The $Li_4Ti_5O_{12}$ powders with various contents of carbon black are almost same at the rate capability for the negative electrode materials in lithium-ion batteries.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.131-137
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• 1998

A composite copper coated powder was generated by pressure hydrogen stripping copper from Kelex 100 solvent extractant in the presence of silica powder. Within the limitation of solvent extraction under constant conditions, both loading level and stripping rate were reproducible. The stripping copper kinetics are reduced from a divalent state to a metallic state and then deposited on the surface of the silica powder. Copper nucleates heterogeneously on the seed particles. They are giving an agglomerated and non - uniform powder.

• Journal of the Korean Society of Safety
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• v.14 no.3
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• pp.48-53
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• 1999

It is widely recognized that Hartmann tube for measuring the minimum ignition energy(MIE) of powder. But It requires long time and operational skills for measuring. As a variety of new fine powders are being produced day by day in industry, Japen has been developing a measurement system which employs a new method to create a dust/air mixture in a miniature combustion box. In this system, by vibration, the powder is successively fed downward through a hopper made up of metal mesh, and then it is formed into a thin, certain-like, dust/air mixture. With this new apparatus, three types of powder-Lycopodium, Anthraquinone, and Polyacry-lonitrile-were tested and the data of MIE were compared with those of a conventional apparatus (the Hartmann tube). Two of them agreed satisfactory, but the other, Anthraquinone, showed quite different values. It is guessed that the agglomerations of the powder particles appear because of particle shapes, static-charge and humidity.