• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2002년도 추계학술발표회요약집
• /
• pp.273.2-273
• /
• 2002

• Journal of Welding and Joining
• /
• 제29권5호
• /
• pp.16-23
• /
• 2011

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
• /
• pp.68.1-68
• /
• 1998

• 한국생산제조학회지
• /
• 제6권4호
• /
• pp.34-38
• /
• 1997

This paper presents a joining method by using the silicon wafer in order to apply to joint to the 3-dimensional structures of semiconductor device, high-speed , high integration, micro machine, silicon integrated sensor, and actuator. In this study, the high atomic beam, stabilized by oxidation film and organic materials at the material surface, is investigated, and the purified is obtained by removing the oxidation film and pollution layer at the materials. And the unstable surface is obtained, which can be easily joined. In order to use the low temperatures for the joint method, the main subjects are obtained as follows: 1) In the case of the silicon wafer and the silicon wafer and the silicon wafer of alumina sputter film, the specimens can be jointed at 2$0^{\circ}C$, and the joining strength is 5Mpa. 2) The specimens can not always be joined at the room temperatures in the case of the silicon wafer and the silicon wafer of alumina sputter film.

• Bulletin of the Korean Chemical Society
• /
• 제20권9호
• /
• pp.1049-1055
• /
• 1999

Electrochemical oxidation of silicon (p-type Si(100)) at room temperature in ethylene glycol and in aqueous solutions has been performed by applying constant low current densities for the preparation of thin SiO2 layers. In-situ ac impedance spectroscopic methods have been employed to characterize the interfaces of electrolyte/oxide/semiconductor and to estimate the thickness of the oxide layer. The thicknesses of SiO2 layers calculated from the capacitive impedance were in the range of 25-100Å depending on the experimental conditions. The anodic polarization resistance parallel with the oxide layer capacitance increased continuously to a very large value in ethylene glycol solution. However, it decreased above 4 V in aqueous solutions, where oxygen evolved through the oxidation of water. Interstitially dissolved oxygen molecules in SiO2 layer at above the oxygen evolution potential were expected to facilitate the formation of SiO2 at the interfaces. Thin SiO2 films grew efficiently at a controlled rate during the application of low anodization currents in aqueous solutions.

• 한국안전학회지
• /
• 제19권4호
• /
• pp.74-79
• /
• 2004

[ $CO_3O_4/{\gamma}-Al_2O_3$ ] catalysts were reported high activity on the low temperature CO oxidation. The effects of the calcination temperature, the loaded amount of cobalt and the oxygen concentration on the characteristics of CO oxidation have been investigated for a emergency escape mask cartridge. $Co(NO_3)_2\cdot6H_2O$ was used as cobalt precursor and the catalysts were prepared by incipient wetness impregnation. TGA shows that enough calcination is accomplished at $450^{\circ}C$ and cobalt phase is $Co_3O_4$ after calcination in the temperature range of $300\ ~500^{\circ}C$. The specific surface area and pore volume of catalysts are decreased with increasing of loaded amount of cobalt. And with the increase of loaded amount of cobalt and the oxygen concentration, the catalytic activity is increased.

• 한국안전학회지
• /
• 제21권2호
• /
• pp.35-45
• /
• 2006

Cobalt catalysts for gas mask loaded on various supports such as $Al_{2}O_{3},\;TiO_{2}$, AC(activated carbon) and $SiO_{2}$ were used to examine influences of calcination temperatures and reaction temperatures for CO oxidation. $Co(NO_{3})_2{\cdot}6H_{2}O$ was used as cobalt precursor and the catalysts were prepared by incipient wetness impregnation. The catalysts were characterized using XRD, TGA/DTA, TEM, $N_{2}$ sorption, and XPS. For the catalytic activity, support was in the order of ${\gamma}-Al_{2}O_{3}>TiO_{2}>SiO_{2}>AC\;and\;Al_{2}O_{3}$. The catalytic activity at lower temperature than $80^{\circ}C$ showed that with the increase of reaction temperature, cobalt catalysts on ${\gamma}-Al_{2}O_{3},\;TiO_{2},\;AC\$ has the negative activation energy but that of $SiO_{2}$ was positive.

• 환경위생공학
• /
• 제13권3호
• /
• pp.72-78
• /
• 1998

For investigation into gas permeation characteristics, the porous alumina membrane with asymmetrical structure, having upper layer with 10 nanometer under of pore diameter and lower layer with 36 nanometer of pore diameter, was prepared by anodic oxidation using DC power supply of constant current mode in an aqueous solution of sulfuric acid. The aluminium plate was pre-treated with thermal oxidation, chemical polishing and electrochemical polishing before anodic oxidation. Because the pore size depended upon the electrolyte, electrolyte concentration, temperature, current density, and so on, the the membranes were prepared by controling the current density, as a very low current density for upper layer of membrane and a high current density for lower layer of membrane. By control of current quantity, the thicknesses of upper layer of membranes were about $6{\;}{\mu}m$ and the total thicknesses of membranes were about $80-90{\;}{\mu}m$. We found that the mechanism of gas permeation depended on model of the Knudsen flow for the membrane prepared at each condition.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 1993년도 추계학술발표회 초록집
• /
• pp.31-36
• /
• 1993

Three different methods were employed to measure the degree of aerial oxidation in coal and the resulting oxidation/weathering indices were applied to obtain kinetic parameters of aerial oxidation processes, The index (i.e., slurry pH, Free Swelling Index, weight gain) values were subjected to kinetic analysis based on power-law Arrhenius type reaction model. The results show that activation energy of the aerial oxidation in 20-29$0^{\circ}C$ is in the range of 12-16 ㎉/㏖ and the agreement among three techniques is remarkable. The first order kinetic model is suitable in describing low temperature aerial oxidation process, except in the FSI case where the zero order expression is the best one.

• 한국재료학회지
• /
• 제32권5호
• /
• pp.264-269
• /
• 2022

Ti₃C₂T_x MXene, which is a representative of the two-dimensional MXene family, is attracting considerable attention due to its remarkable physicochemical and mechanical properties. Despite its strengths, however, it is known to be vulnerable to oxidation. Many researchers have investigated the oxidation behaviors of the material, but most researches were conducted at high temperatures above 500 ℃ in an oxidation-retarding environment. In this research, we studied changes in the structural and electrical properties of Ti₃C₂T_x MXene induced by low-temperature heat treatments in ambient conditions. It was found that a number of TiO₂ particles were formed on the MXene surface when it was mildly heated to 200 ℃. Heating the material to higher temperatures, up to 400 ℃, the phase transformation of Ti₃C₂T_x MXene to TiO₂ was accelerated, resulting in a TiO₂/Ti₃C₂T_x hybrid. Consequently, the metallic nature of pure Ti₃C₂T_x MXene was transformed to semiconductive behavior upon heat-treating at ≥ 200 ℃. The results of this research clearly demonstrate that Ti₃C₂T_x MXene may be easily oxidized even at low temperatures once it is exposed to air.