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전자부품용 메탈라이즈드 알루미나 세라믹스의 미세구조 제어
조범래,Jo, Beom-Rae 한국재료학회 2001 한국재료학회지 Vol.11 No.12
Composition effects on microstructure and metallizing properties of the alumina sintered body were evaluated to develop the metallized alumina tubes having superior properties for electronic devices. SEM observation revealed that resultant micrographs and fractographs were varied with composition chance of additives and $SiO_2$-rich specimens showed better microstructural characteristics with uniform distribution of fine and round particles than other CaO-rich or MgO-rich ones. The resultant interfacial microstructure of the $SiO_2$-rich metallized alumina tubes also showed good metallizing properties with no defects between layers and uniform thickness of metallizing layer.
Effect of composition change on sintering and metallizing of alumina ceramics
조범래,Jung-Jin Lee,강승규 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1
The effects of flux additions on the sintering and metallizing properties of alumina ceramics were investigated. Experimental results showed that the addition of SiO2, CaO and MgO as a flux increases the sintering ability of alumina. An increment in the amount of MgO seems to produce a more uniform and finer grain distribution. CaO and MgO addition seemed to promote a glassy state of the SiO2 easily at a lower temperature. Alumina containing the proper amount of flux additions showed a higher metal-to-bond strength than nearly pure alumina ceramics. This was explained by the fact that the glassy state of SiO2 migrated into the porous metallizing layer during the metallization process. The effects of flux additions on the sintering and metallizing properties of alumina ceramics were investigated. Experimental results showed that the addition of SiO2, CaO and MgO as a flux increases the sintering ability of alumina. An increment in the amount of MgO seems to produce a more uniform and finer grain distribution. CaO and MgO addition seemed to promote a glassy state of the SiO2 easily at a lower temperature. Alumina containing the proper amount of flux additions showed a higher metal-to-bond strength than nearly pure alumina ceramics. This was explained by the fact that the glassy state of SiO2 migrated into the porous metallizing layer during the metallization process.
Eect of Post-Annealing on the Formation of ITO Thin Films
조범래,In-Yong Park 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1
Indium tin oxide(ITO) used in many applications such as electronic and optical devices was deposited on soda-lime glass substrates from a mixture of 90 wt.% of In2O3 and 10 wt.% of SnO₂ at several different substrate temperatures by using an electron beam evaporation technique. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis demonstrated that the lms had a tendency to crystallize along the preferred orientation as the substrate temperature increases. The transmittance of the films increased with an increase in the substrate temperature. The transmittance of the films deposited at 200℃ was about 80 % in the visible light range. The deposited films were post-annealed for 10 minutes at 400℃ in an oxygen environment. The structural, electrical and optical properties of the ITO films were determined as a function of the substrate temperature. The films deposited at higher substrate temperatures showed strong diffraction peaks of preferred orientations. After the post-annealing process, crystallization was also detected in the films deposited at room temperature. Experimental results showed that the sheet resistance of the ITO films was lower after post-annealing. Atomic force microscopy (AFM) observation revealed that the surface roughness increased slightly as the crystallinity increased after post-annealing. Indium tin oxide(ITO) used in many applications such as electronic and optical devices was deposited on soda-lime glass substrates from a mixture of 90 wt.% of In2O3 and 10 wt.% of SnO₂ at several different substrate temperatures by using an electron beam evaporation technique. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis demonstrated that the lms had a tendency to crystallize along the preferred orientation as the substrate temperature increases. The transmittance of the films increased with an increase in the substrate temperature. The transmittance of the films deposited at 200℃ was about 80 % in the visible light range. The deposited films were post-annealed for 10 minutes at 400℃ in an oxygen environment. The structural, electrical and optical properties of the ITO films were determined as a function of the substrate temperature. The films deposited at higher substrate temperatures showed strong diffraction peaks of preferred orientations. After the post-annealing process, crystallization was also detected in the films deposited at room temperature. Experimental results showed that the sheet resistance of the ITO films was lower after post-annealing. Atomic force microscopy (AFM) observation revealed that the surface roughness increased slightly as the crystallinity increased after post-annealing.
SiO<sub>2</sub>와 Al<sub>2</sub>O<sub>3</sub> 첨가가 지르콘의 기계적 특성에 미치는 영향
조범래,Cho, Bum-Rae 한국재료학회 2011 한국재료학회지 Vol.21 No.4
Zircon has excellent thermal, chemical, and mechanical properties, but it is hard to make a dense sintered product because of dissociation during the sintering process. This study analyzes how the addition of $SiO_2$ and $Al_2O_3$ affects the mechanical properties of sintered zircon, particularly in regards to reducing the thermal dissociation and improving the mechanical properties of $ZrSiO_4$. Zircon specimens containing different amounts of $SiO_2$ and $Al_2O_3$ were prepared and sintered to observe how the mechanical properties of $ZrSiO_4$ changed according to the differing amount of $SiO_2$ and $Al_2O_3$. The $ZrSiO_4$ that was used for the starting material was ground by ball mill to an average particle size of 3 ${\mu}m$. The $SiO_2$ and $Al_2O_3$ that was used for additives were ground to an average particle size of 3 ${\mu}m$ and 0.5 ${\mu}m$, respectively. Adding $SiO_2$ resulted in transformation in the liquid phase at high temperatures, which had little effect on suppressing the thermal dissociation but enhanced the mechanical properties of $ZrSiO_4$. When $Al_2O_3$ was added, the mechanical properties of $ZrSiO_4$ decreased due to the formation of pores and abnormal grains in the microstructure of the sintered zircon.
Up-regulation of fibrinogen-like protein 2 in porcine endothelial cells by xenogeneic CD40 signal
조범래,최인호,이은미,허성훈,이병천,안규리 한국통합생물학회 2018 Animal cells and systems Vol.22 No.2
Acute humoral xenograft rejection (AHXR), characterized by thrombin generation and endothelial cell activation, should be overcome for the success of xenotransplantation. Fibrinogen-like protein 2 (fgl2) expressed on endothelial cells can convert prothrombin to thrombin directly, which indicates that the induced fgl2 expression in activated endothelial cells can contribute to thrombosis. In xenotransplant condition, the interaction between human CD40L and porcine endothelial CD40 can activate endothelial cells. In this study, we investigated the effect of endothelial cell activation through the interaction between human CD40L and porcine CD40 on fgl2 expression and its function as a direct prothrombinase. We found that CD40 stimulation up-regulated fgl2 expression as well as its enzymatic activity in porcine endothelial cells. Moreover, functional studies using knock-down system showed that the major factor converting human prothrombin to thrombin is fgl2 protein expressed on porcine endothelial cells. Overall, this study demonstrates that fgl2 expression can be induced by xenogeneic CD40 signal on endothelial cells and contribute to thrombin generation.