• Title/Summary/Keyword: advanced materials

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Advances in liquid crystalline nano-carbon materials: preparation of nano-carbon based lyotropic liquid crystal and their fabrication of nano-carbon fibers with liquid crystalline spinning

  • Choi, Yong-Mun;Jung, Jin;Hwang, Jun Yeon;Kim, Seung Min;Jeong, Hyeonsu;Ku, Bon-Cheol;Goh, Munju
    • Carbon letters
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    • v.16 no.4
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    • pp.223-232
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    • 2015
  • This review presents current progress in the preparation methods of liquid crystalline nano-carbon materials and the liquid crystalline spinning method for producing nano-carbon fibers. In particular, we focus on the fabrication of liquid crystalline carbon nanotubes by spinning from superacids, and the continuous production of macroscopic fiber from liquid crystalline graphene oxide.

Rapid Sintering of Nanostuctured Tungsten Carbide by High-Frequency Induction Heating and its Mechanical Properties (고주파유도 가열에 의한 나노구조의 텅스텐 카바이드 급속소결과 기계적 성질)

  • Kang, Hyun-Su;Doh, Jung-Mann;Hong, Kyung-Tae;Ko, In-Yong;Shon, In-Jin
    • Korean Journal of Metals and Materials
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    • v.48 no.11
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    • pp.1009-1013
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    • 2010
  • Extremely dense WC with a relative density of up to 99% was obtained within five minutes under a pressure of 80 MPa using the High-Frequency Induction Heated Sintering method. The average grain size of the WC was about 71 nm. The advantage of this process is not only rapid densification to obtain a neartheoretical density but also the prohibition of grain growth in nano-structured materials. The hardness and fracture toughness of the dense WC produced by HFIHS were $2660kg{\cdot}mm^{-2}$ and $7.2MPa{\cdot}m^{1/2}$, respectively.

A Preliminary Study on the Characteristics and Criteria of New Material for the Possibility of Application in Housing Space (주거공간에 적용 가능한 신소재 특성 및 기준에 관한 기초 연구)

  • Jung, Sun-Hee;Seo, Ji-Eun
    • Journal of the Korean housing association
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    • v.21 no.4
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    • pp.71-79
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    • 2010
  • This study is a fundamental research which suggests some standards that can be used in selecting some advanced materials to be applied in housing space designs. The following conclusions have been drawn from the study. First, it has been discovered that as the residents' quality of life improved, the finishing materials emerged as an important element of housing spaces. It could also be seen that among the finishing materials used in housing spaces, there is recently a growing trend towards various environmentally-friendly advanced materials under the theme of 'the nature' and 'health'. As a result, the need to investigate the standards of discriminatory and efficient housing space designs using advanced materials is on the increase. Second, through the literature and precedent studies, the physical criteria of advanced materials have been classified into five categories: new technology, new manufacturing methods, new materials, complementation and applicability. The main criteria of advanced finishing materials for housing spaces have been classified into four main categories: durability, functionality, economical efficiency and sensibility. By collecting and classifying some key words according to each of these four categories, the representative or combinable features have been extracted. By organizing the advanced materials' physical criteria and their details, some standards based on the physical aspects have been suggested. The features of the finishing materials in consideration of advanced materials have been reclassified into the user-based criteria, environmental criteria and spatial criteria. Through this method, the criteria have been brought up from a new viewpoint, establishing the standards for the advanced materials applicable to housing spaces. Finally, after assessing the criteria by analyzing the advanced materials currently known to be applicable in housing spaces, it has been concluded that the criteria can be used as the fundamental standards. As this study is based on investigating the literature and data, it may be less than reasonable to generalize from the limited number of examples. Hence, it shall be important to make a profound study of some detailed criteria by suggesting more objective standards and analyzing a greater variety of advanced materials.

Effects of Special Heat Treatments and Alloying Elements on the Microstructures and Mechanical Charateristics of ADI (ADI의 미세조직과 기계적 특성에 미치는 특수열처리 및 합금원소의 영향)

  • Kim, Sug-Won;Han, Sang-Won;Lee, Ui-Jong;Park, Jin-Sung;Woo, Kee-Do;Lim, Dong-Keun
    • Journal of Korea Foundry Society
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    • v.22 no.2
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    • pp.69-74
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    • 2002
  • The effects of heat treatments and alloying elements on the microstructure and mechanical charaterisitics of specially austempered ADIs containing alloying elements such as Cu, Mo and Ni were investigated. To compare with the effect of conventional and normal(CN) austempering treatment, two kinds of special austempering treatments which are those with pre-quenching and pre-heating were conducted. The hardness and uniaxial fatigue tests were carried out to evaluate the mechanical charateristics. The hardness of ADI treated by CN heat cycles was higher than those of other ADIs. Cu added ADI (Cu-ADI) tempered at 400 after austenitizing exhibited the highest fatigue life cycles. While austempering after prequenching makes the austenite with high carbon stable, which resulted in transformation to highly strengthened bainites from the carbon enriched austenite phases during tempering. The high carbon enriched banites is considered to improve the fatigue strength.