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Highly Donor-doped La<sub>x</sub>Ba<sub>1-x</sub>TiO<sub>3</sub> Ceramics
Korobova Nataly,Soh Dea-Wha The Korean Institute of Electrical and Electronic 2003 Transactions on Electrical and Electronic Material Vol.4 No.4
Sol-gel processing of $BaTiO_3$ ceramics doped with La(0.01-1.00 at. $\%$) were prepared from metal barium, titanium n-butoxide and lanthanum iso-propoxide. Characterization of the sol-gel-derived powder using XRD, SEM is also reported. The obtained results showed that insulator to semiconductor transition for highly donor-doped barium titanate was closely related to the incorporation of donor into the grains and to the resultant grain size, which were significantly affected by the sinterability of $BaTiO_3$ powders and sintering conditions used.
HIP Effects on Mechanical Properties of Oxide Plasma-sprayed Coatings
( Korobova N ),( Dea Wha Soh ) 한국동굴학회 2006 동굴 Vol.76 No.-
The present report is the investigation of the effects of the HIP treatment on plasma-sprayed ceramic coating of Al2O3, Al2O3- SiO2 on the metal substrate. These effects were characterized by phase identification, Vickers hardness measurement, and tensile test before and after HIPing.
High-temperature Materials and SHS Products
( Natalya Korobova ),( Dea Wha Soh ) 한국동굴학회 2006 동굴 Vol.76 No.-
Self propagating High temperature Synthesised (SHS) ceramics have been widely used for various electronic applications. The investigation on SHS materials has been reported. The purposes of this study were as follows: fabricating the high temperature functional materials, and evaluating crystal structure and electrical properties. The regularities and peculiarities in SHS structures of high temperature materials as a result of the molecular interactions during burning process are considered.
INVESTIGATION of SPECIAL REFRACTORIES for METAL and GRAPHITE APPLICATIONS
Natalia, Korobova,Soh, Deawha,Park, Sergey 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.-
This work shows that molecular structural variations can be introduced in oxide systems, including Al₂O₃, ZrO₂, Al₂O₃+ZrO₂, by controlled hydrolysis and polymerization reactions during the formation of oxides from metal alkoxides. The chemical and stoichiometric makeup of hydroxides and oxides is not fixed and changes rapidly as a function of molecular size in the region where the size is extremely small. It was also observed that internal structural variations significantly alter the sintering behavior of oxide powders and affect their subsequent crystalline transformations. Refractory materials capable of withstanding corrosion by reducing atmospheres rich in gas, liquid metal and water vapor are necessary Al₂O₃, ZrO₂, ZrO₂+Al₂O₃ of refractories are most attractive economically. Therefore, the reactions of high-temperature oxides with steel were studied to contribute to an understanding of the nature and mechanism of the reactions.
소대화,전용우,이영매,김태완,Korobova, Natalya 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-
In this study, by using the electrophoresis, preparation of YBCO superconducting wire deposited on metal Ag base wire was studied with its properties. YBCO powder could be prepared by solid state reactions with calcining and sintering processes. Superconducting wire prepared on metal Ag wire used as cathode of deposition base could be also fabricated in the YBCO/acetone-dispersed solution to obtain several tens of ㎛ thick films. In the process of film deposition, a catalyst I₂added into the suspension solution was very useful for preparing thick film of YBCO, and BaF₂ of additive material was also necessary for preparing crack-free wire of YBCO superconductor. As a result, YBCO superconducting wire added 2~3wt.% of BaF₂with catalyst, I₂had better deposition condition for uniform and dense YBCO wires, and critical current density, Jc was calculated at the value of 1,458A/㎠ (more than 10³A/㎠, 77K, 0[T]) of 30㎛ thick sample by 4-point prove method.