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Fast Preparation of BSCCO Superconductor by Self-propagation High-temperature Synthesis
Soh, Deawha,Cho, Yongjoon,Park, Seongbeom,Soh, Hyunjoon,Korobova, N. 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-
Abstract - The BSCCO superconductor materials of using Self-propagating High-temperature Synthesis (SHS) were studied. Mechano-chemical activation - as a pretreatment of the reactants mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product. In this paper as an effort for fabricating the SHSed BSCCO superconductor power by SHS method was considered to application in the synthesis of high temperature superconducting materials.
Soh, Deawha,Natalya, Korobova The Korean Institute of Electrical and Electronic 2002 전기전자재료학회논문지 Vol.15 No.3
The peculiarities of using Self-propagating High-temperature Synthesis (SHS) and solid-stave chase synthesis for production of high temperature superconductor materials were discussed. Oxide superconductors with general formula of $ReBa_2Cu_3O_{7-x}$ (Re=Y, Sm) haute been made by using barium oxide initial powder instead of traditional barium carbonate. Phenomena observed during the grinding of the reactants mixture are presented. Mechano-chemical activation - as a pre-treatment of the reactants mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product.
Soh, Deawha,Korobova, N. The Korean Institute of Electrical and Electronic 2002 전기전자재료학회논문지 Vol.15 No.4
The ionic conductivity of cubic solid solutions in the systems of CaO-$ZrO_2$, $Y_2O_3-ZrO_2$ prepared by SHS was examined. The higher conductivity appears to be related to a lower activation energy rather than to the number of oxygen vacancies dictated by composition. Conductivity-temperature data was obtained at 1000 $^{\circ}C$ in atmosphere of low oxygen partial pressure (~$10^{-40}$ atm) for $Y_2O_3-ZrO_2$ cubic solid solutions. The data indicated that these materials could be reduced, and the decree of reduction would be related with the measuring electric field.
Al₂O₃-SiO₂ Dielectric Film Preparation from Metal Alkoxides
Soh, Deawha,Korobova E. Natalya 明知大學校 産業技術硏究所 2005 産業技術硏究所論文集 Vol.24 No.-
The preparation of Al₂O₃-SiO₂ thin films from less than one micron to several tens of microns in thickness had been prepared from metal alkoxide sols. Two methods, dip-withdrawal and electrophoretic deposition, were employed for thin films and sheets formation. The requirements to be satisfied by the solution for preparing uniform and strong films and by the factors affecting thickness and other properties of the films were examined. For the preparation of thin, continuous Al₂O₃-SiO₂ films, therefore, metal-organic-derived precursor solutions contained Si and Al in a chemically polymerized form has been developed and produced in a clear liquid state. In the process of applying to substrates, this liquid left a transparent, continuous film that could be converted to crystalline A1₂O₃-SiO₂ upon heating to l000℃. And, a significant change of the film density took place in the crystallization process, thus leading to the strict requirements as to the film thickness, which could survive crystallization.
Fine YBaCuO Superconducting Powder Prepared by Sol-gel Method
Soh, Deawha,Zhanguo, Fan 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-
Abstract - In order to get proper original suspension for the electophoresis process of making YBaCuO films, YBaCuO superconductor powder was prepared with the Sol-gel method. The composition of the powder was analyzed by X-ray diffraction, which was identified as YBa_2Cu_3O_7-X(Y123) phase. The form of YBaCuO single particle was showed to be spherical by scanning electronic microscope and its size was among 0.2-1 ㎛. The critical transition temperature (T_c) and the critical current density (J_c) were measured with the four-probe method. The T_c was about 91 K, and the J_c was 5-30 A/㎠.
Rapid Synthesis of MoSi₂Heating Elements
Sho, Deawha,Kang, Dohee,Korobova Natalya 明知大學校 産業技術硏究所 2002 産業技術硏究所論文集 Vol.21 No.-
The combustion characteristics of the disilicides molybdenum system have been studied experimentally. The pertinent reaction parameters that control self-propagating high temperature synthesis reactions have been examined. These include reactant particle size, powder mixing and compaction, reaction stoichiometry, diluents. The influence of experimental variables on integrity, uniformity, structure, and related material properties will be discussed. Formation mechanism of MoSi2 during SHS might be different and depending on experimental conditions.
ALUMINUM OXIDE FILM Using Electrophoresis
Soh, Deawha,Park, Sergey,Natalia, Korobova 明知大學校 産業技術硏究所 1997 産業技術硏究所論文集 Vol.16 No.-
Aluminium oxide films has received considerable attention as elevated temperature engineering materials. It has outstanding environmental stability, thermal shock characteristics and physical properties that give it good potential for use as electrical insulators, as thermocouple protection sheaths and as numerous other inert components in elevated temperature and corrosive environments. Dielectric films of aluminium oxide have been prepared by the electrophoretic method from metal alkoxide solution. It has been found the influence of sol "age' on the quality of the films. In this paper formation properties of Al₂O₃ thin amorphous and armoured by whiskers films are discussed. All these films have uniform surface with little or no porosity. The results obtained in the experiments are :(A)The Al₂O₃ films are continuous and free of cracks, (B) adhere well to the stainless steel substrate at high temperature and (C) uniform and smooth surface finish and excellence thermal-shock resistance from-196℃ to room temperature.
액상-고상반응법과 자기전파고온합성법에 의한 YBCO 초전도체의 특성
蘇大和,코로보바 나탈리아,金泰完 明知大學校 産業技術硏究所 2002 産業技術硏究所論文集 Vol.21 No.-
In this paper, instead of YBCO superconductor that used Solid State Reaction method, we propose the construction method using Liquid-Solid State Reaction and Self-propagating High-temperature Synthesis(SHS) method. We developed the SHS method using BaO2 and the liquid-solid state reaction method using BaO, rather than BaCO3, which using YBCO superconductor in solid state reaction method. YBCO superconductor, which was produced through presented method in the above section, using wish the XRD, we can be observed superconductor phase and inspected the superconductivity with producing wire deposition through exectrophoretic deposited, measuring critical temperature and critical current. After measurement of experiment, liquid-solid state reaction and SHS method can be proved excellent 123 phase, critical temperature, which is 92 K and 90 K can be proved better than solid state reaction method's 86 K. Critical current measured by four-probe method can be acquired 0.65 A in solid state reaction, 0.76 A in liquid-solid state reaction, and 0.73 A in SHS method. Each critical current density can be acquired 830 A/㎠, 970 A/㎠, 930 A/㎠(77 K, 0 T) by calculation.
소대화,코로보바 나탈리아,조용준,이영매 明知大學校 産業技術硏究所 2002 産業技術硏究所論文集 Vol.21 No.-
High-Tc superconductor films of YBa2Cu3O7-x were fabricated by electrophoretic deposition (EPD) from alcohol-based suspension, It is very important to select suspension solution for forming electrophoretic deposited YBCO thick film, because it is heavily affected to its superconducting properties. For the formation of YBCO dense and adherent coating on a silver wire by EPD, 1% PEG(1000) 2㎖, as a additive for making their surface crack-free, was used for electrophoresis. In this paper, high-temperature superconductor films of YBa2Cu3O7-x were fabricated by electrophoretic deposition (EPD) from alcohol-based suspension such as iso-propanol, iso-butanol, and their mixture. As a results, the cracks were considerably decreased and the superconducting critical current density (Jc) without/with PEG was 1200 A/㎠ and 2020 A/㎠, which films deposited in 30% iso-PrOH and 70 % iso-BuOH suspensionin mix iso-propanol and iso-butanol suspension.