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적층구조 촉매층(Al/Fe/Al)을 이용한 탄소나노튜브의 합성에서 최상층 알루미늄 층의 역할
송우석,최원철,전철호,류동헌,이승엽,신용숙,박종윤,Song, W.,Choi, W.C.,Jeon, C.,Ryu, D.H.,Lee, S.Y.,Shin, Y.S.,Park, C.Y. 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.5
적층구조 촉매층(Al/Fe/Al)을 이용하여 열 화학기상증착(thermal chemical vapor deposition ; TCVD)법을 통해 탄소 나노튜브를(carbon nanotubes ; CNTs)를 합성하였다. Raman spectroscopy, SEM 및 HR-TEM 분석결과, G/D는 22.7이며, 직경이 $1.14\;{\sim}\;1.32\;nm$인 금속성의 단일벽 탄소 나노튜브(single-walled CNTs ; SWCNTs)의 다발(bundle)들이 기판 전체에 network 구조로 형성되어 있는 것을 확인할 수 있었다. 이는 최상층의 Al이 촉매인 Fe의 응집현상(agglomeration)을 막아주는 역할을 하여 작고 균일한 핵 생성 사이트(nucleation site)를 통해 좁은 직경분포를 가진 단일벽 탄소 나노튜브가 합성되었음을 알 수 있다. In this study, we report the synthesis of the single-walled carbon nanotubes(SWCNTs) using laminated catalyst(Al/Fe/Al) layer deposited by sputter on Si(001). SWCNTs are grown by thermal chemical vapor deposition (TCVD) method. As the results of scanning electron microscopy(SEM), high resolution transmission electron microscopy(HR-TEM) and Raman spectroscopy, we confirmed the SWCNTs bundles with narrow diameter distribution of $1.14{\sim}1.32\;nm$ and average G&D ratio of 22.76. Compare to the sample having Fe/Al catalyst layer, it can be proposed that the top-aluminum incorporated with iron catalyst plays an important role in growing process of CNTs as a agglomeration barrier of the Fe catalyst. Thus, we suggest that a proper quantity of aluminium metal incorporated in Fe catalyst induce small and uniform iron catalysts causing SWCNTs with narrow diameter distribution.
장걸(G. Chang),김은필(E. P. Kim),전철호(C. H. Jeon),이호생(H. S. Lee),문춘근(C. K Moon),윤정인(J. I. Yoon) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The performance of cooling tower is dependent on the thermal performance of the packings. It's assessed by measuring packing characteristic values and pressure drops. In this study, a hybrid fill packing cooing tower is developed by combining the counter flow type fill packing with the cross flow type fill packing. Numerical investigation on the hybrid fill packing cooling tower has been done preliminary to experimental investigation. The result shows that cooling capacity on the hybrid fill packing cooling tower is higher than existing counter and cross flow type cooling tower as the experimental study. But The pressure drops on hybrid fill packing cooling tower are about 20% higher than other type cooling towers.