• Title/Summary/Keyword: Room temperature oxidation

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Influence of Wax Molecular Weights on Wax Migration and Evaporation of Rubber Vulcanizates at Room Temperature (상온 노화 후 고무가황물에서 왁스의 이동과 증발에 미치는 왁스의 분자량 분포)

  • Im, Song-Hee;Choi, Sung-Seen
    • Elastomers and Composites
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    • v.44 no.4
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    • pp.397-400
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    • 2009
  • Ozone caused the crack on the surface of a rubber article by oxidation of double bond at room temperature. Wax migrates to the surface of a rubber article and makes a physical barrier to prevent process of ozonation. We investigated change of molecular weight distribution of waxes in unfilled NR, SBR, and BR vulcanizates before and after aging at room temperature for 6 months. Migration and evaporation behaviors of wax in a rubber article at ambient conditions help understand a role of wax as an antidegradant and appearance contamination of a rubber article. The relative intensity distribution of n-alkanes of the NR specimen after the aging was shifted to higher molecular weight compared with the relative intensity distribution before the aging, while those of the SBR specimen before and after the aging did not show a big difference.

The Microstructures and Mechanical Properties on the GTA Welding conditions of Inconel 617 (Inconel 617 GTA 용접조건에 따른 미세조직 특성 및 기계적성질)

  • Choe, Seong-Bu;Lee, Bong-Geun;Gang, Jeong-Yun
    • Proceedings of the KWS Conference
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    • 2005.11a
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    • pp.171-173
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    • 2005
  • Inconel 617 is a solid solution, nickel-chromium-cobalt-molybdenum alloy with an exceptional combination of high temperature strength and oxidation resistance. The combination of high strenth and oxidation resistance at temperatures over $1800^{\circ}F$ makes Inconel 617 an attractive material for such components as ducting, transition liners in both aircraft and gas turbine. In this study, the weldability and weldment characteristics of Inconel 617 are considered in GTAW associated with the two welding current and with back shielding gas using or not. After GTAW with 120A and 150A current, microstructures and hardness test, bending test, tensile test on room and elevated temperature for the determination of optical welding condition.

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Syntheses and properties of Ti2AlN MAX-phase films

  • Zhang, Tengfei;Myoung, Hee-bok;Shin, Dong-woo;Kim, Kwang Ho
    • Journal of Ceramic Processing Research
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    • v.13 no.spc1
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    • pp.149-153
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    • 2012
  • Ti2AlN MAX-phase films were synthesized through the post-annealing process of as-deposited Ti-Al-N films. Near amorphous or quasi-crystalline ternary Ti-Al-N films were deposited on Si and Al2O3 substrates by sputtering a Ti2AlN MAX-phase target at room temperature, 300 ℃ and 450 ℃, respectively. A vacuum annealing of those films at 800 ℃ for 1 hour changed those films to crystalline Ti2AlN MAX-phase. The polycrystalline Ti2AlN MAX-phase films exhibited very excellent oxidation resistance due to its characteristics microstructure (nanolaminates), which has potential applications for high-temperature protective coatings. The microstructure and composition of Ti2AlN MAX-phase films were investigated using with a variety of characterization tools.

Humidity dependent size control of local anodic oxidation on graphene using Atomic Force Microscope (원자힘 현미경의 습도 조절에 의한 그래핀 국소 산화)

  • Ko, Seoknam;Lee, Seong jun;Son, Maengho;Ahn, Doyeol;Lee, Seung-Woong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2014.11a
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    • pp.226-227
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    • 2014
  • We demonstrate nanoscale local anodic oxidation (LAO) patterning on few layer graphene using atomic force microscope (AFM) at room temperature and normal atmosphere. We focus on the humidity dependency in nanoscale oxidation of graphene. The relationship between the oxidation size and the AFM setting values, such as set point, tip speed, and humidity are observed. By changing these values, proper parameters were found to produce features on demand size. This technique provides an easy way to form graphene oxide lithography without any chemical resists. We have obtained oxidation size down to 50-nm with 6-nm-height oxide barrier line with $0.1{\mu}m/s$ tip scanning speed and micrometer size symbols on a graphene flake. We attribute the bumps to local anodic oxidation on graphene surface and combination of oxygen ions into the graphene lattice.

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The semiconductor carbon nanotube growth with atmosphere pressure chemical vapor deposition method and oxidation effect at $300^{\circ}C$ in air (상압화학기상 증착법에 의한 반도체탄소나노튜브의 성장과 $300^{\circ}C$ 대기에서의 산화열처리 효과)

  • Kim, Jwa-Yeon
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.15 no.2
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    • pp.57-60
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    • 2005
  • Semiconductor carbon nanotube was grown on oxided silicon wafer with atmosphere pressure chemical vapor deposition (APCVD) method and investigated the electrical property after thermal oxidation at $300^{\circ}C$ in air. The electrical property was measured at room temperature in air after thermal oxidation at $300^{\circ}C$ for various times in air. Semiconductor carbon nanotube was steadily changed to metallic carbon nanotube as increasing of thermal oxidation times at $300^{\circ}C$ in air. Some removed area of carbon nanotube surface was shown with transmission electron microscopy (TEM) after thermal oxidation for 6 hours at $300^{\circ}C$ in air.

A Study on Surface Properties in SUS 300 base Stainless Steel (SUS 300계 스테인리스강의 표면특성에 관한 연구)

  • Lee, K.K.;Yoon, D.J.;Ghi, W.B.;Choi, D.C.;Lee, D.J.
    • Journal of the Korean Society for Heat Treatment
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    • v.12 no.1
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    • pp.31-39
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    • 1999
  • In the present study, oxidation behavior of 304 and 316 stainless steels was investigated. After solution treatment, specimens were polished up to $1{\mu}m$ $Al_2O_3$ grade and then subjected to oxidation treatment in dry air. The range of temperature was used for oxidation treatment at $300^{\circ}C{\sim}500^{\circ}C$ and TEM was used for analyzing the components and structure of oxide film. Also, these results were compared with the results of ESCA and TG. According to the results of TEM analysis, it was found that Cr oxide film was formed on top of the surface after room temperature oxidation but amorphous Fe oxide was formed on top of the surface and polycrystalline $(Cr,Fe)_2O_3$ was formed below the amorphous Fe oxide layer after $500^{\circ}C$ oxidation treatment. The oxidized specimens at $500^{\circ}C$ showed that 316 stainless steel resists more strongly to grain and grain boundary oxidation than 304 stainless steel. These results suggested that Mo component resolved in 316 stainless steel matrix suppressed the formation of Cr carbide which may results in local Cr deplete area.

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A Study on Low Temperature Bonding of Si-wafer by Surface Activated Method (표면활성화법에 의한 실리콘웨이퍼의 저온접합에 관한연구)

    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.6 no.4
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    • pp.34-38
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    • 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.

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Oxidation of Amorphous BON Thin Films Grown by RF-PECVD (RF-PECVD 법으로 제조된 비정질 BON박막의 산화)

  • Kim J. W.;Boo J.-H.;Lee D. B.
    • Korean Journal of Materials Research
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    • v.14 no.10
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    • pp.683-687
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    • 2004
  • The BON thin films were grown on the Si substrate by the RF-PECVD method. When stored at the room temperature, the phase separation or transition of BON thin films occurred on the surface, due to the hydrophilic property of BON. The oxidation of BON thin films occurred mainly by the evaporation of B, O and N. The oxidized BON thin films consisted of an amorphous phase and a bit of the polycrystalline phase.

Magnetic CoFe2O4 Nanoparticles as an Efficient Catalyst for the Oxidation of Alcohols to Carbonyl Compounds in the Presence of Oxone as an Oxidant

  • Sadri, Fariba;Ramazani, Ali;Massoudi, Abdolhossain;Khoobi, Mehdi;Azizkhani, Vahid;Tarasi, Roghayeh;Dolatyari, Leila;Min, Bong-Ki
    • Bulletin of the Korean Chemical Society
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    • v.35 no.7
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    • pp.2029-2032
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    • 2014
  • Magnetically nano-$CoFe_2O_4$ efficiently catalyzes oxidation of primary and secondary benzylic and aliphatic alcohols to give the corresponding carbonyl products in good yields. The reactions were carried out in an aqueous medium at room temperature in the presence of oxone (potassium hydrogen monopersulfate) as an oxidant. In addition, the catalysts could be reused up to 6 runs without significant loss of activities. Catalyst was characterized by SEM, XRD and IR.

Rate Enhancement by Micelle Encapsulation for Oxidation of L-Glutamic Acid in Aqueous Media at Room Temperature

  • Mukherjee, Kakali;Saha, Bidyut
    • Journal of the Korean Chemical Society
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    • v.57 no.4
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    • pp.425-431
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    • 2013
  • Oxidation of glutamic acid is performed in aqueous acid media at $30^{\circ}C$ under the kinetic condition [glutamic acid]$_T{\gg}[Cr(VI)]_T$. Effect of combination of micellar catalyst (SDS, TX-100) and promoter (PA, bpy, phen) has been studied. Among the promoters phen accelerates the reaction most in aqueous media. But the rate acceleration is small in the case. Combination of promoter and catalyst produces much better result. Maximum rate enhancement occurs in presence of the combination of bpy and SDS.