• Title/Summary/Keyword: Oxidation stability improvement

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Evaluation of Oxidation Stability for Diesel Engine Oil by Hot-Tube Oxidation Test (Hot-Tube Oxidation Test에 의한 디젤엔진오일의 산화안정성 평가)

  • 정근우;조원오;김영운;서인옥;임수진
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.10a
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    • pp.175-180
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    • 1998
  • This paper describes evaluation of oxidation stability for diesel engine oils by Hot-tube oxidation tester at high temperature. Evaluation was rated by visual inspection of lacquer in capillary glass tube and TAN determination of used oil. Air, NO$_2$-air and SO$_2$-air mixed gases were used as oxidizing gas. One oil which has low oxidation stability is selected and reformulated by addition of some additives such as antioxidant, detergent and disperant to improve oxidation stability. As a results of reformulation, antioxidant and detergent was effective for improvement of high temperture oxidation stability on diesel engine oil.

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Study of Ni-germano Silicide Thermal Stability for Nano-scale CMOS Technology (Nano-scale CMOS를 위한 Ni-germano Silicide의 열 안정성 연구)

  • Huang, Bin-Feng;Oh, Soon-Young;Yun, Jang-Gn;Kim, Yong-Jin;Ji, Hee-Hwan;Kim, Yong-Goo;Wang, Jin-Suk;Lee, Hi-Deok
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.11
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    • pp.1149-1155
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    • 2004
  • In this paper, novel methods for improvement of thermal stability of Ni-germano Silicide were proposed for nano CMOS applications. It was shown that there happened agglomeration and abnormal oxidation in case of Ni-germano Silicide using Ni only structure. Therefore, 4 kinds of tri-layer structure, such as, Ti/Ni/TiN, Ni/Ti/TiN, Co/Ni/TiN and Ni/Co/TiN were proposed utilizing Co and Ti interlayer to improve thermal stability of Ni-germano Silicide. Ti/Ni/TiN structure showed the best improvement of thermal stability and suppression of abnormal oxidation although all kinds of structures showed improvement of sheet resistance. That is, Ti/Ni/TiN structure showed only 11 ohm/sq. in spite of 600 $^{\circ}C$, 30 min post silicidation annealing while Ni-only structure show 42 ohm/sq. Therefore, Ti/Ni/TiN structure is highly promising for nano-scale CMOS technology.

Oxidation Stability of Regenerated Lubricating Oils (II) Formation of anti-Oxidant Materials (潤滑再生油의 酸化安定性能 (第2報). 抗酸化性 物質의 生成)

  • Nah Yun Ho
    • Journal of the Korean Chemical Society
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    • v.19 no.1
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    • pp.50-52
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    • 1975
  • The oxidation stability of samples prepared by blending samples reported previously with diesel oil and diesel oil with additives(alkyl benzene and phenolic type of materials), was tested to study the mechanism of thermal oxidation stability of the regenerated lubricating oils. It was found that the improvement of thermal oxidation stability of such oils was caused by the formation of aromatic compounds, especially phenolic type of organic materials.

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Oxidation Stability of Regenerated Lubricating Oils (Ⅰ). Properties of Regenerated Oils (潤滑再生油의 酸化安定性能 (第1報) 再生油의 性能)

  • Yun Ho Nha
    • Journal of the Korean Chemical Society
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    • v.18 no.6
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    • pp.443-446
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    • 1974
  • The regenerated lubricating oils for an internal combustion engine, obtained from the sulfuric acid and clay treatment, showed an improved thermal oxidation stability regardless of additives, especially anti-oxidant, originally presented in the oils. It is believed that such improvement is due to the formation of anti-oxidant materials, which is observed by the in crease of 25 % of aromatic compounds.

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New Application of Clay Filler for Carbon/Carbon Composites and Improvement of Filler Effect by Clay Size Reduction

  • Jeong, Eui-Gyung;Kim, Jin-Hoon;Lee, Young-Seak
    • Carbon letters
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    • v.11 no.4
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    • pp.293-297
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    • 2010
  • To investigate new potential application of a clay material for C/C composites, illite added C/C composites were prepared with various illite contents. The improvement of filler effect by illite size reduction was also investigated using wet ballmilling by evaluating illite/phenolic resin infiltration using bulk density and porosity measurements, chemical structural changes of the composites using XRD, and thermal oxidation stability in air of the composites using TGA. The size reduction of illite resulted in narrower particle size distribution and improved illite infiltration into carbon preform. And the resultant C/C composites prepared with illite had even more improved thermal oxidation stability in air, showing more increased IDTs up to $100^{\circ}C$, compared to those of the C/C composites with pristine illite, due to the SiC formation through carbothermal reduction between illite and carbon materials. The illite induced delay in oxidation of the illite-C/C composites was also observed and the delayed oxidation behavior was attributed to the layered structure of illite, which improved illite/phenol resin infiltration. Therefore, the potential use of illite as filler to improve oxidation stability of C/C composite can be promising. And the size reduction of illite can improve its effect on the desired properties of illite-C/C composites even more.

Coercivity of Near Single Domain Size Nd2Fe14B-type Particles

  • Kwon, H.W.;Yu, J.H.
    • Journal of Magnetics
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    • v.17 no.3
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    • pp.185-189
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    • 2012
  • The coercivity of near single domain size $Nd_2Fe_{14}B$-type particles prepared by ball milling of HDDR-treated $Nd_{12.5}Fe_{80.6}B_{6.4}Ga_{0.3}Nb_{0.2}$ alloy was investigated. The feasibility of a surface nitrogenation for improving the coercivity stability of the fine $Nd_2Fe_{14}B$-type particles was also studied. The near single domain size $Nd_2Fe_{14}B$-type particles had a high coercivity of over 9 kOe. However, the coercivity radically deteriorated as the temperature increased in air (< 2 kOe at $200^{\circ}C$). This coercivity reduction was attributed to the soft magnetic phases, ${\alpha}$-Fe and $Fe_3B$, which formed on the surface of the fine particle due to oxidation. Surface nitrogenation of the fine particles significantly improved the stability of their coercivity. The improvement in coercivity stability was attributed to the formation of a thin nitrogenated layer on the surface of the fine $Nd_2Fe_{14}B$-type particles, which enhanced the anisotropy field and gave improved resistance to oxidation (dissociation).

A Study on the Oxidation of CO and $C_3H_6$ over Noble Metal Supported Catalysts on Monolith (Monolith에 담지한 귀금속촉매상에서 CO와 $C_3H_6$의 동시적 산화반응에 관한 연구)

  • 김태원;고형림;김재형;김경림
    • Journal of Korean Society for Atmospheric Environment
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    • v.14 no.1
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    • pp.63-72
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    • 1998
  • Simultaneous CO and $C_3H_6$ oxidation was carried out over noble metal supported monolith catalysts in a flow thorugh type reactor at the temperature ranging from room temperature to $500^\circ$C. Pt and Pd were selected as major active species, 10wt% of Ce was impregnated as an additive and alumina and silica were used as supports. The reactant gases were simulated and the reaction products were analyzed by on-line G.C.. EDX, SEM, TGA, XRD and optical microscope were used to analyze the characteristics of the prepared catalysts. Under the given conditions in this study, the catalysts supported on alumina showed better activity for CO oxidation, while Pd catalysts showed better activity for $C_3H_6$ oxidation. The improvement of conversion due to increase in thermal stability possibily by Ce addition was observed only for Pt catalysts.

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Improvement of Oxidative Stability of Myoglobin and Lipid with Vitamin E in Meat (식육내 비타민 E에 의한 육색소와 지질의 산화 안정성 향상)

  • Faustman, Cameron;Lynch, Michael P.;Jeong, Jin-Yeun;Joo, Seon-Tea
    • Food Science of Animal Resources
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    • v.23 no.1
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    • pp.86-95
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    • 2003
  • Potential mechanisms by which vitamin E improves oxidative stability of myoglobin are documented. The basis by which this lipid-soluble antioxidant, ${\alpha}$-tocopherol, protects water-soluble oxymyoglobin is beginning to be understood. Recent evidence suggests that ${\alpha}$-tocopherol delays the release of prooxidative products of lipid oxidation from biomembranes, which in turn delays oxymyoglobin oxidation and the concomitant loss of desirable beef color. ${\alpha}$, ${\beta}$-Unsaturated aldehydes are one class of lipid oxidation products that enhance oxymyoglobin oxidation in vitro and appear to act by covalently binding to the protein. If ${\alpha}$-tocopherol delays the formation of these reactive aldehydes, then this could inhibit the prooxidative effect of these oxidation products toward oxymyoglobin. Additionally, ${\alpha}$-tocopherol may exert part of its color-stabilizing effect in beef by enhancing the metmyoglobin reduction.

Improvement of Chlorophyll-photosensitized Oxidation of Fish Oil-enriched Emulsion by Sesame Oil Addition and Antioxidant Content Changes (참기름 첨가에 의한 어유 보강 에멀젼의 클로로필에 의한 광산화 개선 효과와 산화 방지제 함량 변화)

  • An, Sojin;Lee, Edwald;Choe, Eunok
    • Korean Journal of Food Science and Technology
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    • v.46 no.2
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    • pp.127-134
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    • 2014
  • This study was performed to evaluate the effects of sesame oil addition to a tuna oil-enriched emulsion during chlorophyll-photosensitized oxidation. The emulsion principally consisted of tocopherol-stripped canola and tuna oil with or without sesame oil, acetic acid, phospholipids, and xanthan gum. Chlorophyll b was added to promote the production of singlet oxygen upon exposure to light. The oxidation of oil in the emulsion was evaluated by determining the peroxide value (POV) and conjugated dienoic acid (CDA) contents. Concentrations of minor compounds in the emulsion were monitored. Increasing POV and CDA contents in the emulsion were paralleled with decreased docosahexaenoic acid during oxidation, and oxidation was inhibited by the addition of sesame oil. Chlorophyll, polyphenols, tocopherol, and phospholipids were degraded during oxidation of the emulsion; however, their degradation was slowed down by the addition of sesame oil. Lignans in the emulsions containing added sesame oil were barely changed, suggesting that they quenched singlet oxygen physically. Polyphenols were the most effective in improving the stability of tuna oil-enriched emulsions during chlorophyll-photosensitized oxidation.