• 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.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.359-360
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• 2013

• Preventive Nutrition and Food Science
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• v.16 no.2
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• pp.174-178
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• 2011

The cell permeability and cytotoxic effects of different-sized zinc oxide (ZnO) particles were investigated using a human colorectal adenocarcinoma cell line called Caco-2. Morphological observation by scanning electron microscopy revealed that three zinc oxides with different mean particle sizes (ZnO-1, 20 nm; ZnO-2, 90~200 nm; ZnO-3, $1\sim5\;{\mu}m$) tended to aggregate, particularly in the case of ZnO-1. When cytotoxicities of all three sizes of zinc oxide particles were measured at concentration ranges of $1\sim1000\;{\mu}g$/mL, significant decreases in cell viability were observed at concentrations of $50\;{\mu}g$/mL and higher. Among the three zinc oxides, ZnO-1 showed the lowest viability at $50\;{\mu}g$/mL in Caco-2 cells, followed by ZnO-2 and ZnO-3. The permeate concentration of ZnO-1 from the apical to the basolateral side in the Caco-2 model system after four hours was about three-fold higher than that of either ZnO-2 or ZnO-3. These results demonstrated that ZnO-1, with a 20 nm mean particle size, had poorer viability and better permeability in Caco-2 cells than ZnO-2 and ZnO-3.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.170-170
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• 2010

Thin-film transistors (TFT) have become the key components of electronic and optoelectronic devices. Most conventional thin-film field-effect transistors in display applications use an amorphous or polycrystal Si:H layer as the channel. This silicon layers are opaque in the visible range and severely restrict the amount of light detected by the observer due to its bandgap energy smaller than the visible light. Therefore, Si:H TFT devices reduce the efficiency of light transmittance and brightness. One method to increase the efficiency is to use the transparent oxides for the channel, electrode, and gate insulator. The development of transparent oxides for the components of thin-film field-effect transistors and the room-temperature fabrication with low voltage operations of the devices can offer the flexibility in designing the devices and contribute to the progress of next generation display technologies based on transparent displays and flexible displays. In this thesis, I report on the dc performance of transparent thin-film transistors using amorphous indium tin zinc oxides for an active layer. $SiO_2$ was employed as the gate dielectric oxide. The amorphous indium tin zinc oxides were deposited by RF magnetron sputtering. The carrier concentration of amorphous indium tin zinc oxides was controlled by oxygen pressure in the sputtering ambient. Devices are realized that display a threshold voltage of 4.17V and an on/off ration of ${\sim}10^9$ operated as an n-type enhancement mode with saturation mobility with $15.8\;cm^2/Vs$. In conclusion, the fabrication and characterization of thin-film transistors using amorphous indium tin zinc oxides for an active layer were reported. The devices were fabricated at room temperature by RF magnetron sputtering. The operation of the devices was an n-type enhancement mode with good saturation characteristics.

• Transactions on Electrical and Electronic Materials
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• v.11 no.1
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• pp.1-10
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• 2010

This is an overview paper reporting our most recent work on processing and microstructure of nano-structured oxides and their photoluminescence and photo-catalysis properties. Zinc oxide and related transition metal oxides such as vanadium pentoxide and titanium dioxide were produced by a combination of magnetron sputtering, hydrothermal growth and atmosphere controlled heat treatment. Special morphology and microstructure were created including nanorods arrays, core-brushes, nano-lollipops and multilayers with very large surface area. These structures showed special properties such as much enhanced photoluminescence and chemical reactivity. The photo-catalytic properties have also been promoted significantly. It is believed that two factors contributed to the high reactivity: the large surface area and the interaction between different oxides. The transition metal oxides with different band gaps have much enhanced photoluminescence under laser stimulation. Use of these complex oxide structures as electrodes can also improve the energy conversion efficiency of solar cells. The mixed oxide complex may provide a promising way to high-efficiency photo emitting materials and photo-catalysts.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.166-166
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• 2010

Recently, TFTs based on amorphous oxide semiconductors (AOSs) such as ZnO, InZnO, ZnSnO, GaZnO, TiOx, InGaZnO(IGZO), SnGaZnO, etc. have been attracting a grate deal of attention as potential alternatives to existing TFT technology to meet emerging technological demands where Si-based or organic electronics cannot provide a solution. Since, in 2003, Masuda et al. and Nomura et al. have reported on transparent TFTs using ZnO and IGZO as active layers, respectively, much efforts have been devoted to develop oxide TFTs using aforementioned amorphous oxide semiconductors as their active layers. In this thesis, I report on the performance of thin-film transistors using amorphous indium gallium zinc oxides for an active channel layer at room temperature. $SiO_2$ was employed as the gate dielectric oxide. The amorphous indium gallium zinc oxides were deposited by RF magnetron sputtering. The carrier concentration of amorphous indium gallium zinc oxide was controlled by oxygen pressure in the sputtering ambient. Devices are realized that display a threshold voltage of 1.5V and an on/off ration of > $10^9$ operated as an n-type enhancement mode with saturation mobility with $9.06\;cm^2/V{\cdot}s$. The devices show optical transmittance above 80% in the visible range. In conclusion, the fabrication and characterization of thin-film transistors using amorphous indium gallium zinc oxides for an active channel layer were reported. The operation of the devices was an n-type enhancement mode with good saturation characteristics.

• Bulletin of the Korean Chemical Society
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• v.26 no.7
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• pp.1109-1111
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• 2005

• Corrosion Science and Technology
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• v.10 no.2
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• pp.43-46
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• 2011

Zinc consumption in a continuous galvanizing line is one of the highest operating cost items in the facility and minimizing zinc waste is a key economic objective for any operation. One of the primary sources of excessive loss of zinc is through the formation of top dross and skimmings in the coating pot. It has been reported that the top skimmings, manually removed from the bath, typically consist of more than 80% metallic zinc with the remainder being entrained dross particles ($Fe_2Al_5$) along with some oxides. Depending on the drossing practices and bath management, the composition of the removed top skimmings may contain up to 2 wt% aluminum and 1 wt% iron. On-going research efforts have been aimed at in-house recovery of the metallic zinc from the discarded top skimmings prior to selling to zinc recycling brokers. However, attempting to recover the zinc entrapped in the skimmings is difficult due to the complex nature of the intermetallic dross particles and the quality and volume of the recycled zinc is highly susceptible to fluctuations in processing parameters. As such, an efficient method to extract metallic zinc from top skimmings has been optimized through the use of a specialized thermo-mechanical process enabling a continuous galvanizing facility to conserve zinc usage on-site. Also, through this work, it has been identified that filtration of discrete dross particles has been proven effective at maintaining the cleanliness of the zinc. Future efforts may progress towards expanded utilization of filters in continuous galvanizing.

• Journal of the Semiconductor & Display Technology
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• v.6 no.1 s.18
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• pp.65-69
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• 2007

A design of experiments was applied in order to investigate the effect of processing variables in UV irradiation on the electrical/optical properties in indium-zinc oxide thin films, The processing variables, equivalently input variables are listed as UV irradiation time, oxygen flow rate, and chamber pressure. The statistical significance of Ultra Violet (UV) treatment was confirmed using a paired-t test. The full factorial $2^3$ design was employed to determine significant main and interaction effects in UV irradiation process. The chamber pressure and the interaction between UV irradiation time and $O_2$ flow rate were found to be statistically significant at the significance level of 0.1. Furthermore, the optimized approach was proposed in achieving the improved conductivity after UV irradiation.

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.144-144
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• 2006