• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.310-315
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• 1997

An extensive corrosion study was initiated by galvalume steel sheet manufacturing company to clarify the corrosion behavior of zinc and zinc and zinc-alloy coated automotive sheet steel in out panel and electrical application. Since the early 1980's the use of zinc and aluminum alloy coated steel for vehicular corrosion protection has increased drastically. This paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shape of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel has no problem for the variation of welding current. And tip lifetime was changed according to the influence of shape.

• Resources Recycling
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• v.9 no.1
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• pp.15-20
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• 2000

The effect of different kinds of steel scraps, the raw material in the manufacturing of nodular cast iron, on the microstructures and mechanical properties has been investigated Different grades were produced by changing the steel scraps. When nodular graphite cast iron was produced by using Zn rich steel scrap, such as galvanized steel sheet and auto body sheet, mechanical properties were deteriorated due to the decomposition of graphite, so close control must be maintained over this element. Tensile strength and hardness of nodular graphite cast iron which were manufactured by using Sb rich steel scrap were increased while elongation was decreased due to the increased amounts of pearlite within matrix. Mn and Cr contents in the structural steel sheet scrap or malleable iron scrap increased tensile strength and hardness of nodular graphite cast iron by facilitating the formation of pearlite.

• Korean Journal of Metals and Materials
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• v.48 no.2
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• pp.116-121
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• 2010

The Mg-Zn-RE alloy cladded with the thin Al1050 sheet was fabricated by means of a roll bonding process at $280^{\circ}C$.Microstructures and mechanical properties of the clad sheets were investigated. After heat treatment at $230^{\circ}C$ for 30 min, an Mg-rich diffusion layer with about $2{\mu}m$ in thickness was developed at the Mg and Al interface. Tensile tests were carried out in a temperature range up to $300^{\circ}C$. The clad sheet exhibits superior elongation to failure not only at room temperature but also at elevated temperatures compared with those of the Mg alloy sheet. For the deformed specimens, interface debonding does not occur and the diffusion layer shows only a few cracks.

• Journal of the Korean institute of surface engineering
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• v.53 no.3
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• pp.104-108
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• 2020

ZnO single layer films (100 nm thick) and Au intermediated ZnO films (ZnO/Au/ZnO; ZAZ) were deposited on the glass substrate by RF and DC magnetron sputtering at room temperature and then the influence of the Au interlayer on the electrical and optical properties of the films were investigated. ZnO thin films show the visible transmittance of 90.3 % and sheet resistance of 63.2×10⁸ Ω/□. In ZAZ films, as Au interlayer thickness increased from 6 to 10 nm, the sheet resistance decreased from 58.3×10⁸ to 48.6 Ω/□, and the visible transmittance decreased from 84.2 to 73.9 %. From the observed results, it can be concluded that the intermediate Au thin film enhances the opto-electrical performance of ZnO films without intentional substrate heating.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.43-46
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• 2011

In this study, we investigated the effects of the post Ar plasma treatment at different RF powers for various durations on electrical, structural, and optical properties of relatively thin Al-doped zinc oxide films. The sheet resistance was observed to decrease rapidly for the first 5min, beyond which the resistance apparently saturated. As the RF power increased, the grain size and the interplanar distance of (002) planes also increased. The observed decrease in sheet resistance was stated to be a consequence of Al and/or Zn interstitials as well as grain growth. It was also found that Ar plasma treatment increased the transmittance of Al-doped zinc oxide films in most of the visible light range below the blue light.

• Journal of Welding and Joining
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• v.18 no.2
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• pp.191-191
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• 2000

The mechanism of the blowhole and the pit formation in lap-jointed fillet CO₂ arc welds of Zn-coated steel sheet was established by the direct observation of the gas behavior in the molten pool with the high speed camera system. Main conclusions obtained are as follows1) Some blowholes were formed by incomplete back-filling to the pits at the last stage of the solidification. This type of blowhole was formed through four stages of gas in the molten pool, incubation, explosion, back-filling and completion of back-filling stage.2) Most of the pits was back-filled at the last stage of their formation. (Received September 27, 1999)

• Journal of Welding and Joining
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• v.18 no.2
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• pp.64-68
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• 2000

The mechanism of the blowhole and the pit formation in lap-jointed fillet Co₂arc welds of Zn-coated steel sheet was established by the direct observation of the gas behavior in the molten pool with the high speed camera system. Main conclusions obtained are as follows: 1) Some blowholes were formed by incomplete back-filling to the pits at the last stage of the solidification. This type of blowhole was formed through four stages of gas in the molten pool, incubation, explosion, back-filling and completion of back-filling stage. 2) Most of the pits was back-filled at the last stage of their formation.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.2
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• pp.75-79
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• 2009

Precipitate formations and grain size variations in various Mg-Sn-Zn alloys have been investigated and their effects on the tensile properties and sheet metal formability were evaluated. MgSn and MgZn precipitates were observed in the alloy sheets, however any clear difference in morphology or size for the precipitates could not be found even though MgSn precipitates tend to be larger than MgZn. The highest formability in terms of conical cup value was found in the Mg-4 wt%Sn-2 wt%Zn where the high tensile elongation and the reduced grain coarsening at elevated temperatures were observed.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.242-244
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• 2015

ZnO:Ga thin films were deposited by RF magnetron sputtering technique from ZnO (3 wt.% $Ga_2O_3$) target onto glass substrates under various RF power. The influence of RF power on the structural, electrical, and optical properties of ZnO:Ga thin films was investigated by X-ray diffraction, atomic force microscopy, Hall method and optical transmission spectroscopy. As the RF power increases from 50 to 110W, the crystallinity is deteriorated, the root main square surface roughness is decreased and the sheet resistance is increased. The increase of sheet resistance is caused by decreasing carrier concentration due to interstitial Ga ion. All films are transparent up to 80% in the visible wavelength range and the adsorption edge is a red-shift with increasing RF power.

• Corrosion Science and Technology
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• v.23 no.3
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• pp.221-227
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• 2024

During hot stamping of hot-dip zinc-coated steel sheets such as hot-dip galvanized steel sheets and hot-dip galvannealed steel sheets, an oxide mainly composed of ZnO is formed on the sheet surface. However, excessive formation of ZnO can lead to a decrease in the amount of metal Zn in the coating layer, decreasing the corrosion resistance of hot-stamped members. Therefore, it is important to suppress excessive formation of ZnO. While the formation of Al oxides and Mn oxides along with ZnO layer during the hot stamping of hot-dip zinc-coated steel sheets can affect ZnO formation, crystal structures of such oxides have not been elucidated clearly. Thus, this study aimed to analyze structures of oxides formed during hot stamping of hot-dip galvannealed steel sheets using transmission electron microscopy. Results indicated the formation of an oxide layer comprising ZnAl₂O₄ at the interface between ZnO and the coating layer with Mn₃O₄ at the outermost of an oxide layer.