• Journal of Powder Materials
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• v.25 no.2
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• pp.137-143
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• 2018

In this study, two types of SKD61 tool-steel samples are built by a selective laser melting (SLM) process using the different laser scan speeds. The characteristics of two kinds of SKD61 tool-steel powders used in the SLM process are evaluated. Commercial SKD61 tool-steel power has a flowability of 16.68 sec/50 g and its Hausner ratio is calculated to be 1.25 by apparent and tapped density. Also, the fabricated SKD61 tool steel powder fabricated by a gas atomization process has a flowability of 21.3 sec/50 g and its Hausner ratio is calculated to be 1.18. Therefore, we confirmed that the two powders used in this study have excellent flowability. Samples are fabricated to measure mechanical properties. The highest densities of the SKD61 tool-steel samples, fabricated under the same conditions, are $7.734g/cm^3$ (using commercial SKD61 powder) and $7.652g/cm^3$ (using fabricated SKD61 powder), measured with Archimedes method. Hardness is measured by Rockwell hardness testing equipment 5 times and the highest hardnesses of the samples are 54.56 HRC (commercial powder) and 52.62 HRC (fabricated powder). Also, the measured tensile strengths are approximately 1,721 MPa (commercial SKD61 powder) and 1,552 MPa (fabricated SKD61 powder), respectively.

• ETRI Journal
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• v.32 no.2
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• pp.342-344
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• 2010

A novel, maskless, low-volume bumping material, called solder bump maker, which is composed of a resin and low-melting-point solder powder, has been developed. The resin features no distinct chemical reactions preventing the rheological coalescence of the solder, a deoxidation of the oxide layer on the solder powder for wetting on the pad at the solder melting point, and no major weight loss caused by out-gassing. With these characteristics, the solder was successfully wetted onto a metal pad and formed a uniform solder bump array with pitches of 120 ${\mu}m$ and 150 ${\mu}m$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.366-369
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• 2003

High T$_{c}$ superconducting lines will be applied as key materials in the areas of power transmission line; magnetic levitation of vehicle; magnetic separation; magnetic energy storage and marine propulsion. A combination method of electrophoresis deposition and zone-melting for preparation of YBaCuO tape is proposed. The submicron particle powder of YBaCuO made by sol-gel method is used in the electrophoresis process. A 40~50${\mu}{\textrm}{m}$ thickness of YBaCuO film on Ag plate could be deposited in about three minutes. After deposition the film is rolled and heat treated in order to increase the density and the adhesion of the film to the Ag plate. Silver(Ag) and lead oxide(PbO) were added in the YBaCuO powder in order to reduce its melting point. The YBaCuO coating with controlled Ag and PbO contents was preliminarily zone-melted at about 945$^{\circ}C$.>.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.688-689
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• 2006

Ni-doped $CoSb_3$ was prepared by the encapsulated induction melting and hot pressing, and its doping effects on the thermoelectric properties were investigated. Single phase $\delta-CoSb_3$ was successfully obtained by the subsequent heat treatment at 773K for 24 hours. Nickel atoms acted as electron donors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by the appropriate doping.

• Journal of information and communication convergence engineering
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• v.1 no.2
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• pp.63-66
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• 2003

High $T_c$ superconducting lines will be applied as key materials in the areas of power transmission line; magnetic levitation of vehicle; magnetic separation; magnetic energy storage and marine propulsion. A combination method of electrophoresis deposition and zone-melting for preparation of YBaCuO tape is proposed. The submicron particle powder of YBaCuO made by sol-gel method is used in the electrophoresis process. A 40∼50 ${\mu}\textrm{m}$ thickness of YBaCuO film on Ag plate could be deposited in about three minutes. After deposition the film is rolled and heat treated in order to increase the density and the adhesion of the film to the Ag plate. Silver(Ag) and lead oxide(PbO) were added in the YBaCuO powder in order to reduce its melting point. The YBaCuO coating with controlled Ag and PbO contents was preliminarily zone-melted at about $945^{\circ}C$.

• Journal of the Korean Applied Science and Technology
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• v.28 no.3
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• pp.351-358
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• 2011

It was researched to be alternative of TGIC type hardener with human hazard element as PT 910 mix powder paint with hardener. Generally PT 910 was compared with TGIC & Epoxy resin of hardener to be used at thermosetting powder paint. We inquired a property of matter for paint through Gel time, glass transition temperature, melting point and a property of matter for film through a property of adhesion, a property of tolerance, softness, gloss, acid-resistant, alkali-resistant, salt water spray-resistant, facilitation climatic. When PT 910 is used of hardener, it was shown the excellent results in gel time, softness, salt water spray-resistant, fracilitation climatic and the similar results in melting point, a property of tolerance, a property of adhesion, gloss, acid-resistant, alkali-resistant, as compared with the powder paint used by TGIC hardener. The glass transition temperature was little low. But there was slightly different results. After the study results, we reached the conclusion that thermosetting powder used by PT 910 is alterative to by TGIC hardener.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1245-1246
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• 2006

We fabricated Bi-2212/$SrSO_4$ composite superconductors and evaluated the effects of the powder mixing method and melting temperature on their microstructure and superconducting properties. The Bi-2212 powders were mixed with $SrSO_4$ by hand-mixing (HM) and planetary ball milling (PBM) and then the powder mixtures were melted at $1100^{\circ}C{\sim}1200^{\circ}C$, solidified, and annealed. We found that the powder mixture prepared by PBM was finer and more homogeneously mixed than that prepared by HM, resulting in more homogeneous microstructure and smaller $SrSO_4$ and second phases after annealing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1775-1777
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• 2009

BiSrCaCuO films were prepared on MgO single substerate at $885^{\circ}C$ by melt process. The films showed superconductivity above liquid nitrogen temperature (Tc= 96K). To investigate the effect of a melting temperature on the forming of the surface texturing, the samples were prepared under various temperature. The used powder was of high Tc phase. It is implies that the origin of the properties due to the heat treatment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.204-209
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• 1995

The implementation of rapid prototyping technologies has been developed for automotive engineering by utilizing concurrent engineering principes integrated with slective laser sintering. The Selective Laser Sintering, in which a part is generated in layers form powder using a computer-controlled laser scanning apparatus and power feed system. An over view of the basic principles of SLS Machine operation is given. Binding mechanisms are described for power which becomes thermally activated bye the scanning laser beam; viscous flow and melting of a low-melting-point phase in powder. The production of parts from metal is described, including post processing to improve structural integrity and induce a transformation.

• Journal of Powder Materials
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• v.21 no.1
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• pp.1-6
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• 2014

Medical technologies are gaining in importance because of scientific and technical progress in medicine and the increasing average lifetime of people. This has opened up a huge market for medical devices, where complex-shaped metallic parts made from biocompatible materials are in great demand. Today many of these components are already being manufactured by powder metallurgy technologies. This includes mass production of standard products and also customized components. In this paper some aspects related to metal injection molding of Ti and its alloys as well as modifications of microstructure and surface finish were discussed. The process chain of additive manufacturing (AM) was described and the current state of the art of AM processes like Selective Laser Melting and electron beam melting for medical applications was presented.