• Transactions of Materials Processing
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• v.25 no.6
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• pp.353-358
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• 2016

Direct energy deposition (DED) is an additive manufacturing technique that involves the melting of metal powder with a high-powered laser beam and is used to build a variety of components. In recent year, it can be widely used in order to produce hard, wear resistant and/or corrosion resistant surface layers of metallic mechanical parts, such as dies and molds. For the purpose of the hardfacing to achieve high wear resistance and hardness, application of high speed steel (HSS) can be expected to improve the tool life. During the DED process using the high-carbon steel, however, defects (delamination or cracking) can be induced by rapid solidification of the molten powder. Thus, substrate preheating is generally adopted to reduce the deposition defect. While the substrate preheating ensures defect-free deposition, it is important to select the optimal preheating temperature since it also affects the microstructure evolution and mechanical properties. In this study, AISI M4 powder was deposited on the AISI 1045 substrate preheated at different temperatures (room temperature to $500^{\circ}C$). In addition, the micro-hardness distribution, cooling rates, and microstructures of the deposited layers were investigated in order to observe the influence of the substrate preheating on the mechanical and metallurgical properties.

• Korean Journal of Materials Research
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• v.12 no.1
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• pp.82-88
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• 2002

Chromium carbide films were deposited on high speed steels using a Cr_3C_2$ target by magnetron sputtering. Effects of the deposition parameters (power, Ar pressure and substrate temperature) on deposition rates and surface roughnesses of the films were investigated. The morphologies of those films were characterized by scanning electron microscopy and atomic force microscopy. The grain size of the samples deposited using dc-power is larger than that using equivalent rf-power. The hardness of the sample increases with increasing rf-power, whereas the elastic modulus nearly does not change with rf-power. The optimum sputter deposition conditions for chromium carbide on high speed steels in the corrosion resistance aspect were found to be the rf-power with small roughness.

• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.647-651
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• 2016

SiC films were prepared on glassy carbon substrates by laser chemical vapor deposition under a high pressure of $10^4Pa$ using a diode laser (wavelength = 808 nm) and a polysilaethylene precursor. (111)-oriented SiC films were formed at a deposition temperature ($T_{dep}$) range of 1150 - 1422 K. At $T_{dep}=1262K$, the SiC film with a high Lotgering factor of above 0.96 showed an exhibited pyramid-like surface morphology and flower-like grains. The highest deposition rate ($R_{dep}$) was $220{\mu}m\;h^{-1}$ at $T_{dep}=1262K$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4711-4717
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• 2011

Formation of TiN films by PVD method and the DC and RF sputtering deposition method can be applied, the injected gas to generate plasma ionization rate of the film forming speed is slow away, anything to increase the adhesion between films limitations have. To improve this, to investigate the deposition and ion beam evaporation simultaneously IBAD(Ion beam assisted deposition) when used, Ion beam surface coating material prior to the survey because the surface cleaning effect of a large, high film adhesion can be obtained. In addition, the high vacuum and low temperature, high purity thin film of uniform thickness in the benefits is.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.277-277
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• 2012

New concept of coating process, which is called Electro Magnetic Levitation-Physical Vapour deposition (EML-PVD) was developed and investigated. Zinc coating was performed and succeeded for the first time on the steel strip (Cold-rolled Steel) in a continuos pilot line using the EML-PVD process which is specialized in the high deposition rate and high vapor yield. EML-PVD will be expected to be the next generation coating technology to be applied to the steel industry.

• Progress in Superconductivity and Cryogenics
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• v.6 no.3
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• pp.27-32
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• 2004

High temperature superconducting coated conductor has a structure of /< superconducting layer>//. The buffer layer consists of multi layer, and the architecture most widely used in RABiTS approach is CeO$_2$(cap layer)/YSZ(diffusion barrier layer)/CeO$_2$(seed layer). Evaporation technique is used for the CeO$_2$ layer and DC reactive sputtering technique is used for the YSZ layer, A chamber was set up specially for DC reactive sputtering, Detailed features are as following. A separator divided the chamber into two halves a sputtering chamber and a reaction chamber. The argon gas for sputtering target elements flows out of the cap of sputtering gun, and water vapor for reaction with depositing species spouts near the substrate. Turbo pump is connected with reaction chamber. High speed deposition of YSZ film could be achieved in the chamber. Detailed deposition conditions (temperature and partial pressure of reaction gas) were investigated for the rapid growth of high quality YSZ film.

• Journal of the Korean Society of Visualization
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• v.21 no.1
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• pp.26-30
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• 2023

Interaction of a droplet and substrate is important to determine the coating and final deposition pattern in inkjet printing system. In particular, an accurate deposition of the droplet should be guaranteed for high-resolution patterning. In this study, we performed high-speed shadowgraph experiments on droplet train impact in inkjet system. From the high-speed images, we observed an unexpected bouncing phenomenon. We have found two factors affecting bouncing regime; the Weber number and the curvature of deposited droplet. Experimental results indicate that there is a critical curvature diameter of deposited droplet, which splits into bouncing and merging regime. From this result, we obtained a power-law behavior between the Weber number and the curvature. The understanding of bouncing phenomena helps to improve the accuracy and productivity of inkjet printing.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.23.2-23.2
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• 2009

Atomic layer deposition (ALD)have been proven to be a very attractive technique for the fabrication of advanced gate dielectrics and DRAM insulators due to excellent conformality and precise control of film thickness and composition, However, one major disadvantages of ALD is its relatively low deposition rate (throughput) because the deposition rate is typically limited by the time required for purging process between the introduction of precursors. In order to improve its throughput, many efforts have been made by commercial companies, for example,the modification reactor and development of precursors. However, any promising solution has not reported to date. We developed a new concept ALD system(Lucida TM S200) with high-throughput. In this process, a continuous flow of ALD precursor and purging gas are simultaneously introduced from different locations in the ALD reactor. A cyclic ALD process is carried out by moving the wafer holder up and down. Therefore, the time required for ALD reaction cycle is determined by speed of the wafer holder and vapor pressure of precursors. We will present the operating principle of our system and results of deposition.

• Journal of Welding and Joining
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• v.34 no.1
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• pp.35-40
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• 2016

Recent developments of Laser metal 3D deposition with wire feeding are reviewed which provide an alternative to powder feeding method. The wire feeding direction, angle and position as well as laser power, wire feeding rate, and deposition speed are found to be key parameters to make quality deposition with high throughput. When compared with the powder feed, the wire feed shows higher material efficiency, higher deposition rate, and smoother surface. Large elongated columnar grains which have epitaxial growth across deposit layers are observed in deposit cross sections. The growth direction is parallel to the thermal gradient during the deposit process. Tensile properties are found to be dependent on the direction due to the anisotropic deposit property. A real-time feedback control is demonstrated to be effective to improve the deposition stability.

• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1188-1196
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• 1994

TiN films were deposited onto high speed steel(SKH9) and silicon wafer by plasma-assisted chemical vapor deposition(PACVD) using a TiCl4/N2/H2/Ar gas mixture. The effects of deposition temperature, R.F. power, and H2 concentration on the deposition of TiN were studied. The residual chlorine content and the microhardness of TiN films were also investigated. It was found that TiN films grew with a columnar structure of a strong (200) preferred orientation regardless of the substrate type and the deposition variables. The TiN films consisted of columnar-grains of about 50 to 100 nm in diameter. The columnar grains themselves contained much finer fibrous grains. As deposition temperature increased, the residual chlorine content decreased sharply. R. F. powder enhanced the deposition rate largely. Increasing of H2 concentration had little effect on the residual chlorine.