• Proceedings of the Korean Society of Rheology Conference
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• 2002.05a
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• pp.149-152
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• 2002

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8363-8369
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• 2015

This study is to be investigate properties of workability, compacting and compressive strength replaced by the illite powder in high fluidity concrete. For this purpose, illite powder has replaced the binder of high fluidity concrete of 5%, 10%, 15%, 20%. After concrete mixing, slump flow test, reach time slump flow 500mm, O-lot test were conducted on fresh high fluidity concrete. And compressive strength was determined 28 days for the hardened high fluidity concrete specimens. According to the test results, the workability, filling height of high fluidity concrete were increased in 10% replacement of illite powder. Furthermore, the compressive strength of high fluidity concrete was increased in 10% replacement of illite powder.. It was possible to confirm that optimal mixture ratio of illite powder seems to exist, and it is shown to be 10% according to our experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.4
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• pp.333-339
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• 2008

Densification behavior of copper powder was investigated to study the effect of an aluminum mold under warm pressing. The low flow stress of an aluminum mold is appropriate to apply hydrostatic stress to powder compacts during compaction under high temperature. The suggested powder metallurgy process is very useful under high temperature since copper powder compacts have higher relative density over axial stress of 100 MPa and show more homogeneity as compared with conventional warm pressing. Elastoplastic constitutive equation proposed by Shima and Oyane was implemented into a finite element program (ABAQUS) for densification behavior under warn pressing by using a metal mold. Finite element results agreed well with experimental data for densification and deformation of copper powder compacts in the mold.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.128-129
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• 2015

Recently, a number of problems due to the CO₂ emissions are occurred. Therefore, it is a movement to restrict this activity. The research is being carried out steadily for recycling waste concrete from the cement paste based fine powder, which accounts for over 60% of construction waste as a recycled cement. In this study, the conclusion was obtained as a result of the research conducted, and then, replacing the main material of cement concrete to solve the above problem by reducing the amount of cement used Waste Concrete Powder. The more concrete results page replacement ratio of fine powder increases, the flow value of the concrete is lowered, the strength was remarkably reduced when the page Concrete Powder.

• Journal of Powder Materials
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• v.9 no.1
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• pp.11-18
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• 2002

The 6061 Al alloy based composites reinforced with 10 vol% SiC whiskers were prepared by powder metallurgy with the powders having the different sizes, i.e. < $30{\mu}m$ and > $30{\mu}m$ The composites were subjected to equal channel angular pressing (ECAP) at various conditions and the microstructural changes during ECAP were examined In the composites SiC whiskers were clustered and randomly aligned. The clusters were relatively well distributed in the composite with the smaller initial powder size. After ECAP, the clusters were aligned parallel to flow direction and became smaller. In addition, the shape of clusters was changed from irregular to round. The microstructure of the ECAPed samples were compared with those of the conventionally hot-extruded composites. The uniform microstructure and enhanced microhardness could be obtained by using the powders having the smaller size, decreasing ECAP temperature and repeating ECAP.

• 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.

• Journal of Powder Materials
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• v.15 no.4
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• pp.292-296
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• 2008

The electromagnetic (EM) wave absorption properties of the $Fe_{73}Si_{16}B_7Nb_3Cu_1$ nanocrystalline powder mixed with 5 to 20 vol% of Ni-Zn ferrites has been investigated in a frequency range from 100MHz to 10GHz. Amorphous ribbons prepared by a planar flow casting process were pulverized and milled after annealing at 425 for 1 hour. The powder was mixed with a ferrite powder at various volume ratios to tape-cast into a 1.0mm thick sheet. Results showed that the EM wave absorption sheet with Ni-Zn ferrite powder reduced complex permittivity due to low dielectric constant of ferrite compared with nanocrystalline powder, while that with 5 vol% of ferrite showed relatively higher imaginary part of permeability. The sheet mixed with 5 vol% ferrite powder showed the best electromagnetic wave absorption properties at high frequency ranges, which resulted from the increased imaginary part of permeability due to reduced eddy current.

• Journal of Powder Materials
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• v.25 no.3
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• pp.220-225
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• 2018

The microstructure and mechanical characteristics of SUS630 specimens fabricated using the direct energy deposition (DED) process are investigated. In DED, several process parameters such as laser scan speed, chamber gas flow, powder carrier gas flow, and powder feed rate are kept fixed; the laser power is changed as 150 W, 180 W, and 210 W. As the laser power increases, the surface becomes smooth, the thickness uniformity improves, and the size and number of pores decreases. With the increase in laser power, the hardness deviation decreases and the average hardness increases. The microstructure of the material is columnar; pores are formed preferentially along the columnar interface. The lath-martensite phase governs the overall microstructure. The volumetric fraction of the retained austenite phase is measured to increase with the increase of laser input power.

• Computers and Concrete
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• v.20 no.3
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• pp.283-290
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• 2017

The aim of this study is to investigate the effect of the bond strength of self-compacting mortars (SCMS) produced from ground pumice powder (GPP) as a mineral additive. In this scope, six series of mortars including control mix were prepared that consist of 7%, 12%, 17%, 22% and 27% of ground pumice powder by weight of cement. A total of 54 specimens of $40{\times}40{\times}160mm$ were produced and cured at the age of 3, 28 and 90-day for compressive and tensile strength tests and 18 specimens of $150{\times}150{\times}150mm$ mortar were prepared and cured at 28 days for bond strength tests. Flexural tensile strength and compressive strength of $40{\times}40{\times}160mm$ specimens were measured at the curing age of 7, 28 and 90-day. Mini V-funnel flow time and mini slump flow diameter tests were also conducted to obtain rheological properties. As a result of the study, it was observed that the SCMs containing 12% of GPP has the highest bond strength as compared to control and GPP mortars. Compressive strength slightly increased up to 12% of GPP.

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.391-397
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• 2002

Synthesis and process development of nano-size Ti powder by SFE(Sodium/halide Flame Encapsulation) method were investigated. Four concentric coflow burner was used and its flame configuration was $TiCl_4/Ar/Na/Ar$ in order from the center. Flame has been controlled by the various processing parameters such as temperature of burner and flow rates of both $TiCl_4$(g) precursor and Na(g). It was found that yellow-colored flame was shown in the flow rates of 70cc/min of $TiCl_4$(g) precursor and 2 $\ell$ /min of Na(g) which were regarded as optimum flame condition. The powders encapsuled by NaCl were produced having the average powder size of 250nm. The results of X-ray diffraction showed that powders from the optimized condition consisted of pure Ti and NaCl. TEM analysis confirmed that the several Ti powders of 20-100nm were encapsulated with NaCl. After removing sodium chloride by heat treatment, the spherical Ti powders with the size range of 80 to 150nm were obtained.