• Journal of Korea Foundry Society
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• v.29 no.5
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• pp.233-237
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• 2009

The effect of electrolyte on mechanical and corrosion properties of AZ91 magnesium alloy by plasma electrolytic oxidation (PEO) method was investigated. The coating layers formed in the silicate and the aluminate electrolytes showed porous structures. The small pores were randomly distributed on the coatings formed in aluminate electrolyte while the coatings formed in silicate electrolyte showed much bigger pores. In the aluminate electrolyte, the coatings were composed of Mg, MgO and $MgAl_2O_4$, whereas Mg, MgO, $MgAl_2O_4$ and $Mg_2SiO_4$ were identified in the coatings formed in silicate electrolyte. The hardness of coatings in the silicate electrolyte was higher than that of coating grown in the aluminate electrolyte. The AZ91 alloy coated in the silicate electrolyte had higher tensile strength and elongation than that coated in the aluminate electrolyte. In addition, the coatings formed in the silicate electrolyte showed much better corrosion resistance compared to the coatings formed in the aluminate electrolyte.

• Journal of the Korean Ceramic Society
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• v.35 no.3
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• pp.303-309
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• 1998

The fabrication of Al2O3/Al composite by pressureless infiltration was investigated by the change of Mg and Si content in Al alloy infiltration process and infiltration atmosphere. The effect of alloying elements infiltration atmosphere and interfacial reactants between Al alloy matrix and Al2O3 particles were in-vestigated in terms of bendingstrength and harness test,. The fabrication of Al2O3/Al composite by the vestigated in terms of bending strength and hardness test. The fabrication of Al2O3/Al composite by the pressureless infiltration was done in nitrogen atmosphere with Mg in Al alloy. It was successfully fabricated at $700^{\circ}C$ according to Mg contents in Al alloy and infiltration condition. Because Mg in the Al alloy and ni-trogen atmosphere of infiltratio condition produced Mg-N compound(Mg3N2) it decreased the wetting an-gle between molten Al alloy and Al2O3 particles by coating on surface of Al2O3 particles. The fracture strength of Al2O3/Al-Mg composite was 800MPa and Al2O3/Al-Si-Mg composite was 400MPa. Si in Al alloy decreased the interfacial strength between Al alloy matrix and Al2O3 particles.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1538-1541
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• 2009

Amphiphobic thin films for touched panel application was prepared by $SiO_2$ nanoparticles self-assembled nanostructure. Silicon dioxide nano spheres were prepared by sol-gel method and well dispersed in a solution with surfacants of low surface energy. Nanostrcture thin films were obtained by spin coating technologies.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.55-55
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• 2008

반사방지막은 태양전지 셀 제작에 적용되고 있으며, 효율을 향상시키기 위하여 $SiO_2$, $TiO_2$를 이용한 Multi-layer 반사방지막을 적용하였다. Multi-layer의 효과가 기존의 SiN 반사방지막에 비하여 광수집의 향상에 영향을 주었음을 알 수 있었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.109-110
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• 2013

Medium carbon steel was aluminized by hot dipping into molten Al or Al-1%Si baths. After hot-dipping in these baths, a thin Al-rich topcoat and a thick alloy layer rich in $Al_5Fe_2$ formed on the surface. A small a mount of FeAl and $Al_3Fe$ was incorporated in the alloy layer. Silicon from the Al-1%Si bath was uniformly distributed throughout the entire coating. The hot dipping increased the microhardness of the steel by about 8 times. Heating at $700-1000^{\circ}C$ however decreased the microhardness through interdiffusion between the coating and the substrate. The oxidation at $700-1000^{\circ}C$ in air formed a thin protective ${\alpha}-Al_2O_3$ layer, which provided good oxidation resistance. Silicon was oxidized to amorphous silica, exhibiting a glassy oxide surface.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.360-364
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• 2010

$Li_4Ti_5O_{12}$ thin film with inverse hemispheric structure was fabricated on a Pt/Ti/$SiO_2$/Si substrate by the sol-gel and dip coating method for use as an anode for 3-dimensional (3D) thin-film batteries. Polystyrene (PS) beads of 400 nm diameter were used to prepare the template for the inverse hemispheric structure. A coating solution prepared using precursor sources was dropped on the template-deposited substrates, which were then calcinated at $400^{\circ}C$. The template was removed by calcination, and the inverse hemispheric structure was successfully formed by an annealing process. The cyclic performance during high-rate charge/discharge processes of the $Li_4Ti_5O_{12}$ film with inverse hemispheric structure was superior to that of the flat $Li_4Ti_5O_{12}$ film.

• Journal of the Korean Ceramic Society
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• v.42 no.3 s.274
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• pp.150-154
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• 2005

Ferroelectric $Bi_{3.35}Sm_{0.65}Ti_{3}O_{12}(BSmT)$ thin films were synthesized by sol-gel process. In this experiments, $Bi(TMHD)_{3},\;Sm_{5}(O^{i}Pr)_{13},\;Ti(O^{i}Pr)_4$ were used as precursors, which were dissolved in 2-methoxyethanol. The BSmT thin films were deposited on the Pt/TiO/SiO/Si substrates by spin-coating. Thereafter, the thin films with the thickness of 240 nm were annealed from 600 to $720^{\circ}C$ in oxygen atmosphere for 1 h, and post-annealed in oxygen atmosphere for 1 h after deposition of Pt electrode to enhance the electrical properties. To investigate the effects of Sm-substitution in the BTO thin films, the BTO and BSmT thin films were prepared, respectively. The remanent polarization and coercive voltage of the BSmT thin films annealed at $720^{\circ}C$ were $19.48{\mu}C/cm^2$ and 3.40 V, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.328-328
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• 2011

Wetting phenomena have been heavily studied for industrial and academic researches especially tuning the wettability between hydrophilicity and hydrophobicity. Wicking through the surface texture is shown on superhydrophilic surface while rolling (or dewetting) on the patterns of superhydrophobic surface. These wetting phenomena are known to be affected by surface wettability determined with physical surface patterns as well as chemical composition of surface layer. In this research, we introduce a method to control the wettability of a thin C-SiOx film from hydrophobic to hydrophilic using a mixture gas of HMDSO/$O_2$ by plasma polymerization with rf-CVD (radio frequency-Chemical Vapor Deposition). Wettability was finely controlled by changing the ratio of HMDSO/$O_2$. Hydrophilicity increased as the ratio decreased, while hydrophobicity was enhanced by the ratio. Moreover, fine control from superhydrophilicity to superhydrophobicity was achieved by C-SiOx coating on the Si wafer with prepatterns of submicron-sized pillar array formed by $CF_4$ plasma etching.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.3
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• pp.211-218
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• 2000

$PbZrO_3$precursor was prepared for the spin coating on the Pt/Ti/$SiO_2$/Si substrate. Two different heat treatment methods were used and the differencies were studied. One of the method is that the films were inserted into the furnace for 30 minutes and the other is that the films were annealed by rapid thermal annealing (RTA) for 1 minute at the same temperatures. We also examined the tendency of crystallization by annealing at the fixed temperature, $700^{\circ}C$ as a function of time, namely during 1, 10, 20, and 30 minitues, respectively. The optimum conditions for the crystallization of these films were at $550^{\circ}C$ during 30 min. and at $700^{\circ}C$ during 10 min. in muffle furnace and at $650^{\circ}C$ during 1 min in RTA furnace. The best condition for making good quality grains needs 30 min. at $700^{\circ}C$.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.613-618
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• 2003

The magnetic heating effect of $SiO_2$coated $ \Upsilon-Fe_2$$O_3$nanocomposite particle due to magnetic relaxational loss of superparamagnetic regime was investigated by measuring the generated heat from nanocomposite particles in alternative applied magnetic fields. The commercial $ \Upsilon-Fe_2$$O_3$nanoparticles were coated by SiO$_2$in water solution with TEOS and the synthesized nanocomposite powders and its magnetic properties were characterized and compared with the raw$ \Upsilon-Fe_2$$O_3$nanoparticles. The 10∼30 nm sized $ \Upsilon-Fe_2$$O_3$. nanoparticles were coated by 5 nm thickness of amorphous $SiO_2$film. The nanocomposite particle has very low Mr and Hc value showing superparamagnetic behavior The magnetic heating effect of nanocomposite particle on surface coating phase of $SiO_2$was discussed in terms of superparamagnetic behaviors of each particles, and their potential for hyperthermia application was evaluated.