• Journal of Ocean Engineering and Technology
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• v.12 no.1
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• pp.32-38
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• 1998

This paper is to investigate of microhardness, adhesive strength, tensile strength, and fatigue strength of ceramic sprayed steel. Rotary bending fatigue tests have been conducted at room temperature in air and 3% NaCl solution using specimens of carbon steel(S45C) with sprayed coating layers of Ni-4.5% Al(under coating) and $TiO_2$ (top coating). The microhardness has been improved at $800^{\circ}C$ heat treatment and 150mm spraying distance. Tensile strength of the sprayed steel is dependent on the substrate strength. The fatigue strength of the sprayed steel is larger than that of substrate due to blasting and constraint surface of plastic deformation effect. In low stress level, the corrosion fatigue strength of the sprayed steel were lower than that of fatigue strength in air by corrosion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.262-263
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• 2005

Pt counter electrode based on flexible metal for dye-sensitized solar cells(DSCs) has been investigated. Photovoltaic structures on lightweight substrates have several advantages over the heavy glass-based structures in both terrestrial and space applications. Cyclic voltammetry and impedance spectroscopy were used to investigate electrochemical properties of Pt counter electrode both FTO glass and SUS sheet substrate. The DSCs composed of the counter electrode based on a stainless steel substrate has obtained conversion efficiencies comparable to that based on the conducting glass. The counter electrode based on the stainless steel substrate has the merit of improving the fill factor and conversion efficiency of the DSCs by reducing its internal resistance.

• Membrane and Water Treatment
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• v.6 no.3
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• pp.251-262
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• 2015

In this work the preparation and characterization of a membrane containing a uniform mesoporous Titanium oxide top layer on a porous stainless steel substrate has been studied. The 316 L stainless steel substrate was prepared by powder metallurgy technique and modified by soaking-rolling and fast drying method. The mesoporous titania membrane was fabricated via the sol-gel method. Morphological studies were performed on both supported and unsupported membranes using scanning electron microscope (SEM) and field emission scanning microscope (FESEM). The membranes were also characterized using X-ray diffraction (XRD) and $N_2$-adsorption / desorption measurement (BET analyses). It was revealed that a defect-free anatase membrane with a thickness of $1.6{\mu}m$ and 4.3 nm average pore size can be produced. In order to evaluate the performance of the supported membrane, single-gas permeation experiments were carried out at room temperature with nitrogen gas. The permeability coefficient of the fabricated membrane was $4{\times}10^{-8}\;lit\;s^{-1}\;Pa^{-1}\;cm^{-1}$.

• 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.

• Laser Solutions
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• v.3 no.1
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• pp.29-37
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• 2000

For a development purpose of thick metal / metal Graded-Boundary Materials(GBM), a basic research on the fabrication of Ni-Cr/steel GBM was carried out by a laser beam and its mechanical properties and thermal characteristics were investigated. In order to produce a compositionally graded boundary region between substrate steel and added Ni-Cr alloy, a series of surface alloying treatments was performed with a high power CO$_2$ laser beam. Ni-Cr sheet was placed on a low carbon steel plate(0.18%C), and then a CO$_2$ laser beam was irradiated on the surface to produce a homogeneous alloyed layer. On this first surface-alloyed layer, another Ni-Cr sheet was placed and then the CO$_2$ laser beam was irradiated again to produce second surface-alloyed layer. Sequential repetitions of laser surface alloying treatment 4 times resulted in a graded-boundary region with the thickness of about 1.4mm. Simultaneous concentration profiles of different kinds of alloying elements(Ni and Cr) showed from 42%Ni, 45%Cr and 13%Fe on surface region to 0%Ni, 0%Cr and 99%Fe in substrate region. Also a thermal conductivity gradient resulted in graded-region and its value changed from 0.03㎈/cm s$\^{C}$ in surface region to 0.1㎈/cm s$\^{C}$ in substrate region. Microstructural observation showed that any visible root porosities and solidification shrinkage cracks were not formed in graded region between alloyed layer and substrate region during rapid cooling.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.892-896
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• 2005

In this paper, key issues of stainless steel foil substrates for display applications have been described. We studied and analyzed technical issues on substrate passivation/planarization to control surface roughness and capacitive coupling from conductive substrates. A thick (either multiple or single) passivation/planarization layer needs to be applied on the nonelectronic-grade stainless steel substrate to provide a smooth surface and electrical insulation from the conductive substrate. Especially for large size, high-resolution display applications, low k and thick passivation/planarization layers should be used for appropriate capacitive coupling. Based on our initial study, a unit area capacitance of less than $2nF/cm^2$ of passivation/planarization layers is needed for 32" HD TV OLED displays.

• Journal of the Korean institute of surface engineering
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• v.26 no.6
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• pp.316-326
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• 1993

Adhesion and hardeness are the most important properties of a hard coated layer which is applied to wear-resistant devices. Zr/ZrN layer was deposited on tool steel(SKH9) and stainless steel(SUS304) by a re-active D.C. magnetron sputtering technique and their microhardness and adhesion strength were measured for the films processed by changing the partial pressures of $N_2$ gas (4~10$\times$$10^{-4}$mbar) and the substrate bias voltage(0~250V). The adhesion strength was evaluated by acoustic signals through the scratch-test with the incremental applied load. As the partial pressure of $N_2$ gas and the substrate bias voltage were increased, the adhesion strength of tool steel was observed to be stronger than that of the stainless steel. The adhesion strength was generally, observed to decrease with the same tendency regardless of the kinds of substrates. The adhesion strength of tool steel was increased more and more strongly than that of stainless steel as heat-treated temperature was increased. The strength of tool steel was appeared to be high adhesion strength at $400^{\circ}C$. From the failure mode of the film during the scratch adhesion test, the cohesive failure was observed to be obvious and the adhesive failure in a minor portion in the Zr/ZrN doublelayer regardless of the kinds of substrates.

• Journal of Power System Engineering
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• v.1 no.1
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• pp.70-79
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• 1997

Ni-base self-fluxing alloy powder particles were flame sprayed onto the SS400 mild steel substrate surface. The effects of both substrate temperature and spraying distance on the splat behavior of sprayed particles were examined. The results obtained are summarized as follows: 1) In the splat behavior of Ni-base self-fulxing alloy particles sprayed onto the SS400 mild steel substrate, splashing was observed under the room temperature condition. On the contrary, it showed circular plate pattern in the substrate temperature range over 373K. 2) It was cleared that there was close relationship between mechanical properties of coating layer and splat behavior of sprayed particles. 3) From the experimental results, optimum spraying conditions showed excellent mechanical properties in the case of Ni-base self fluxing alloy sprayed onto the SS400 mild substrate were 473K of substrate temperature and 250mm of spraying distance.

• Journal of the Korean institute of surface engineering
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• v.35 no.1
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• pp.33-38
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• 2002

For the evaluation of nucleation and growth behaviors influenced by substrate properties, such as surface energy, structure and electrical properties, chromium nitride films (CrN) were deposited on various substrates (glass, AISI 1040 steel and Si (110) by unbalanced magnetron sputtering. X-ray diffraction and Atomic Force Microscopy (AFM) were used to study the microstructure and grain growth as a function of deposition time. The diffraction patterns of CrN thin films deposited on Si (110) exhibited crystalline structure with highly preferred orientation of (200) plane parallel to the substrate, whereas the films deposited on glass and AISI 1040 exhibited preferred orientations (200) and minor orientation (111), (311) or (220) plane. The orientation of films deposited both on glass and Si substrates did not depend on the bias voltage (Vs). The grain growth and structure of film deposited on AISI 1040 steel substrate are strongly influenced by the substrate bias in comparison with that deposited onto glass and Si substrates. The differences in the structure and grain growth of CrN films deposited onto different substrates are predominantly related to the properties of the substrate (structure and electrical conductivity).

• Solar Energy
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• v.10 no.1
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• pp.57-62
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• 1990

The influence of substrate materials on the thermal stability of black chrome coating was investigated by Rutherford backscattering spectrometry(RBS). In order to study thermal degradation the sample were annealed in air for 24 hour at temperature of 450. Cu, Ni, and S.S(Stainless steel 304) were used as substrate for selective coating. The experimental results of substrate diffusion was discussed. It was found that little diffusion of substrate material occurred for the sample pre. pared on stainless steel.