• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.859-864
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• 2006

For the pressure compaction process of the ceramic powder, the green density is very different with both the ceramic body shape and the processing conditions. The density difference cause non-uniform shrinkages and deformations, and make cracks in the sintered ceramics. In this paper, Material properties of the alumina powder mixed with binder and the friction coefficient between the powder and the tool set were determined through the simple compaction experiments: Also the powder flow characteristics were simulated and the green density was analyzed during the powder compaction process with Finite Element Method (FEM). The results show that the density distributions of the green body were improved at the optimized processing condition and both the possibility of the farming crack generation and rho deformation of the sintered Alumina body were reduced.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.20-21
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• 2006

Through different projects, CETIM and its scientific and industrial partners have evaluated the potential of the High Velocityy Compaction Technology in terms of materials and component shape. Various kinds of powder materials were studied: metals, ceramics and polymers. The HVC process was used with success to manufacture gears, large parts and multilevel components. Due to the high density of HVC parts, the green machining process enables shapes to be produced that would otherwise be impossible to compact and components to be produced with very hard sintered and homogeneous materials.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.1
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• pp.21-26
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• 2005

In order to simulate the powder compaction process and to assess the effects of packing randomness and particle arrangement 2-dimensional model of rod array compaction using quasi-random multiparticle array is introduced. The elastic modulus of porous ceramics is computed by the homogenization method. With 3 Al₂O₃ and 3 Al particles the compaction processes associated with the porosities are simulated by the explicit finite element method, based on the elastic modulus found by the homogenization method. The simulation results are compared with both previous analytical ones and experimental measurements. Finally, in order to find the relationship between the friction coefficient of powder particles and the relative density, the sensitivity analysis is performed.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.368-369
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• 2006

By means of magnetic pulsed compaction and sintering of weakly aggregated alumina based nanopowders the jet forming nozzle samples for the hydroabrasive cutting were fabricated. The ceramics was obtained from pure alumina, as well as from alumina, doped by $TiO_2$, MgO and AlMg. It was shown that the samples sintered from AlMg doped $Al_2O_3$ powder have the best mechanical properties and structural characteristics: relative density ${\sim}0.97$, channel microhardness. - 18-20 GPa, channel surface roughness ${\sim}0.7\;{\mu}m$, average crystallite size ${\sim}1\;{\mu}m$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.1
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• pp.27-33
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• 2005

In this study, the process parameters in ceramics powder compaction are optimized for getting high relative densities of ceramic products. To find optimized parameters, the analytic models of powder compaction are firstly prepared by 2-dimensional rod arrays with random green densities using a quasi-random multiparticle array. Then, using finite element method, the changes in relative densities are analyzed by varying the size of Al₂O₃ particle, the amplitude of cyclic compaction, and the coefficient of friction, which influence the relative density in cyclic compactions. After the analytic function of relative density associated process parameters are formulated by aid of the response surface method, the optimal conditions in powder compaction process are found by the grid search method. When the particle size of Al₂O₃ is 22.5 ㎛, the optimal parameters for the amplitude of cyclic compaction and the coefficient of friction are 75 MPa and 0.1103, respectively. The maximum relative density is 0.9390.

• Proceedings of the Korean Ceranic Society Conference
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• 2004.10a
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• pp.88.2-88.2
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• 2004

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.24-25
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• 2006

High-Speed Centrifugal Compaction Process is one of slip-using compacting method originally developed for processing of oxide ceramics. In this study, we apply the HCP to ultra-fine (0.1 micron) WC powder. Organic liquid of heptane was chosen as dispersing media to avoid possible oxidation of WC. The mixing apparatus was a key to obtain dense compacts. Only the slips mixed by high energy planetary ball mill were packed up to 55% by the HCP, and sintered to almost full density at 1673 K without any sintering aids. This sintered compact marked Vickers hardness of Hv 2750 at maximum.

• Korean Journal of Materials Research
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• v.27 no.12
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• pp.716-721
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• 2017

SiAlON-based ceramics are some of the most typical ceramic materials used as cutting tools for HRSA(Heat Resistant Super-Alloys). SiAlON can be fabricated using ceramic processing, such as mixing, granulation, compaction, and sintering. Spray drying is a widely-used method for producing a granular powder of controlled morphology and size with flowability. In this study, we report a systematic investigation aimed at optimizing spherical granule morphology by controlling spray-drying parameters such as gas flow and feed rate. Before spray drying, the viscosities of the raw material slurries were also optimized with the amount of dispersant added.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.775-775
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• 2006

• Journal of Powder Materials
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• v.12 no.5 s.52
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• pp.345-350
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• 2005

In this study the nanostructured ${\alpha}-Al_{2}O_3$ ceramics have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent spark plasma sintering (SPS), and their density and hardness properties were investigated. The ${\alpha}-Al_{2}O_3$ prepared by the combined processes showed an increase by $8.4\%$ in density, approaching the value close to the true density, and an enhancement by $210\~400\;Hv$ in hardness, compared to those fabricated by MPC or static compaction method followed by sintering treatment.