Yong-Tae An

P₂O₅-SnO₂계 유리에서 P₂O₅를 B₂O₃로 치환첨가 시 구조와 물성에 미치는 영향

ABSTRACT P 2 O 5 -SnO 2 system 0.5SnO 2 -xP 2 O 5 0.(5--x)B 2 O 3 (x = 0.1, 0.2, 0.3, 0.4, 0.5) glasses have been prepared for Pb-free low temperatureglass frit. A investigation about the effect of B 2 O 3 substitution on properties of P 2 O 5 glasses, including glass structure properties,thermal properties, and mechanical properties was presented. Substance that is responsible for in moisture absorption existingcircumstances supposes by phosphate, and excess moisture tolerance that state funerals structure is improved breaking does not affectin state funeral bond that only most single bond remains, and can know that does not suffer big impact in boric oxide anomaly p reneststate. This phenomenon estimates that connect with structure change. It is thought according to link this result the phosphoric acidhappened structural change. B 2 O 3 displacement quantity 0.3 mole put out BO 4 structures, but above 0.3 mole it changed with the caseBO 3 structure which it displaces.Key words : SnOP₂O?-SnO₂ system 0.5SnO₂-xP₂O?-(0.5-x)B₂O₃(x=0.1, 0.2, 0.3, 0.4, 0.5) glasses have been prepared for Pb-free low temperature glass frit. A investigation about the effect of B₂O₃ substitution on properties of P₂O? glasses, including glass structure properties, thermal properties, and mechanical properties was presented. Substance that is responsible for in moisture absorption existing circumstances supposes by phosphate, and excess moisture tolerance that state funerals structure is improved breaking does not affect in state funeral bond that only most single bond remains, and can know that does not suffer big impact in boric oxide anomaly present state. This phenomenon estimates that connect with structure change. It is thought according to link this result the phosphoric acid happened structural change. B₂O₃ displacement quantity 0.3 mole put out BO₄ structures, but above 0.3 mole it changed with the case BO₃ structure which it displaces.

고체산화물연료전지 연결재용 La 0.7 Ca 0.3 Cr 0.9 Co 0.1 O 3-δ 조성계에 Ca Source 변화에 따른 소결 및 전기적 특성에 관한 연구

Effects on sintering and electrical properties of La 0.7 Ca 0.3 Cr 0.9 Co 0.1 O 3-δ system, a interconnect material for cylindrical and flat tubular solid oxide fuel cells (SOFC), have been investigated by Ca-source when using CaCO₃ and CaF₂.. When using CaCO₃ and CaF₂ was mixing as Ca-source, single phased perovskite solid solution was observed for each sample. The sintering temperature was decreased by CaF₂ contents was increased. When using 0.1 mole CaF₂ was densely sintered at 1400℃ and relative density was 93.8%. Also, electrical conductivity in oxidation and reducing atmosphere was 47, 4.3 S/㎝, respectively, due to F?ion enhance the electrical conductivity in reducing atmosphere.

Fabrication and Cell Properties of Flattened Tube Segmented-in-Series Solid Oxide Fuel Cell-Stack Using Decalcomania Paper

In the segmented-in-series solid-oxide fuel cells (SIS-SOFCs), fabrication techniques which use decalcomania paper have many advantages, i.e., an increased active area of the electrode; better interfacial adhesion property between the anode, electrolyte and cathode; and improved layer thickness uniformity. In this work, a cell-stack was fabricated on porous ceramic flattened tube supports using decalcomania paper, which consists of an anode, electrolyte, and a cathode. The anode layer was 40 µm thick, and was porous. The electrolyte layers exhibited a uniform thickness of about 20 µm with a dense structure. Interfacial adhesion was improved due to the dense structure. The cathode layers was 30 µm thick with porous structure, good adhesion to the electrolyte. The ohmic resistance levels at 800, 750 and 700 o C were measured, showing values of 1.49, 1.58 and 1.65 Ω·cm 2 , respectively. The polarization resistances at 800, 750 and 700 o C were measured to be 1.63, 2.61 and 4.17 cm 2 , respectively. These lower resistance values originated from the excellent interfacial adhesion between the anode, electrolyte and cathode. In a two-cell-stack SOFC, open-circuit voltages(OCVs) of 1.915, 1.942 and 1.957 V and maximum power densities(MPD) of 289.9, 276.1 and 220.4 mW/cm 2 were measured at 800, 750 and 700 o C, respectively. The proposed fabrication technique using decalcomania paper was shown to be feasible for the easy fabrication of segmented-in-series flattened tube SOFCs.

SnO₂-(1-x)P₂O₅ -xB₂O₃ 유리의 열적, 구조적 특성

SnO₂-(1-x)P₂O? -xB₂O₃ glass system were prepared by melt-quenching technique in the compositional series containing 50, 55 and 60 ㏖% of SnO₂. Local structure of the glasses was investigated by Raman and FT-IR measurements. A large glass-forming region was found at the phosphate side of the ternary system with homogeneous glasses containing up to 5~25 ㏖% of B₂O₃. According as content of B₂O₃ increases, theraml expansion coefficient of glass decreased but transition temperature and softening temperature increased. Because these phenomenon changed local structure of glass. According as content of B₂O₃ increases, quantity of bridging oxygen increased. Also, according as content of SnO₂ increases, confirmed that quantity of non-bridging oxygen increases.

Power Densities According to Anode Functional Layers on the Manufactured SOFC Unit Cells Using Decalcomania Method

The properties of SOFC unit cells manufactured using the decalcomania method were investigated. SOFC unit cell manufacturing using the decalcomania method is a very simple process. In order to minimize the ohmic loss of flattened tube type anode supports of solid oxide fuel cells(SOFC), the cells were fabricated by producing an anode function layer, YSZ electrolyte, LSM electrode, etc., on the supports and laminating them. The influence of these materials on the power output characteristics was studied when laminating the components and laminating the anode function layer between the anode and the electrolyte to improve the output characteristics. Regarding the performance of the SOFC unit cell, the output was 246 at a temperature of in the case of not laminating the anode function layer; however, this value was improved by a factor of two to 574 due to the decrease of the ohmic resistance and polarization resistance of the cell in the case of laminating the anode function layer. The outputs appeared to be as high as 574 and 246 at a temperature of in the case of using decalcomania paper when laminating the electrolyte layer using the in dip-coating method; however, the reason for this is that interfacial adhesion was improved due to the dense structure, which leads to a thin thickness of the electrolyte layer.

Dielectric Characteristics on Filler Content and Sintering Temperature in Pb-Free White Dielectric Layer

For the development of a new white dielectric layer in plasma display panel, different types as a filler was add to the -BaO-ZnO glass matrix. The reflectance and dielectric constant of dielectric have been investigated as a function of the mixing content (rutile and anatase), and sintering temperature. The reflectance of dielectric sintered at the 520 appeared most highly and suitable in terms of the adhesion and reflectance of the soda-lime glasses. Also, the thermal expansion coefficient of dielectric was found to be , which was similar to that of the soda-lime glasses. Especially, the dielectric constants were not increased with increasing of filler contents.

The Effect of Acid Treatment Time for Ni Plating on the Joint of α-Al 2 O 3 and Ni Metal

>> In Na-base Battery for ESS, α-Al2O3 and metal bonding was used to prevent direct reaction between electrolyte and electrode. The hard metal was metalized at 1600°C in a flowing hydrogen gas for high bonding strength. In this study, instead of hard metal metalizing, Ni was plated on α-Al2O3 by electroless Ni plating technique and then bonded with metal. To enhance the bonding strength, surface of α-Al2O3 was treated with H3PO4. The effects of strength and leakage of joining as a function of acid treatment time on α-Al2O3 are described.

Behavior of precipitation and morphological, structural properties during the synthesis of spherical Ni and Ni0.95M0.05(M=Cu, Cr, Co, Fe) nano-particles

Spherical Ni and Ni0.95M0.05(M=Cu, Cr, Co, Fe) nano-particles were synthesized using hydrazine reduction method. The objective of this study is to investigate how the different metallic species affect the reduction rate when nano-sized metallic particles are synthesized by the precipitation method. It was found that the pH and reaction temperature had significant influence over the size and morphology of the synthesized metallic nano-particles. Ni0.95Cu0.05 solution showed highest reduction precipitation rate, while Ni0.95Cr0.05 showed slowest rate among the metallic species investigated in this study. At higher reaction temperature, the precipitated metallic particles showed higher degree of crystallinity. The particles synthesized at higher the pH had smaller surface area because the surface of the particles became smoother. It was found that the crystallographic lattice either contract or expand depending on the substituting metallic species. It is concluded from this study that the morphology and size of the spherical Ni and Ni0.95M0.05 nano-particles can be controlled by solution temperature and pH as well as metallic species added. This is due to different reaction rate resulted from difference in reduction potential and activation energy at different temperature and pH.