입자 크기에 따라 상전이 경로가 달라지며 매우 큰 응집체로 존재하는 gibbsite 분말과 같은 재료의 정량적인 전이 구조 분석의 전제로서 입자 크기가 선택적인 TEM 시편의 준비가 절실히 요구된다. 입자 크기 선택성을 실현한 TEM 시편 준비의 방법론을 확립하기 위한 방안으로서 본 실험이 전개되었다. 약 1 wt%의 gibbsite 원료 분말을 에탄올 용매에 혼합 한 뒤, ball-milling에 의해 조분쇄 처리를 하고 증류수에 1 : 19의 비로 희석된 분산 조제, Darvan C, 0.25 vol%의 첨가와 함께 ultrasonic 처리를 하여 gibbsite suspension을 만들었다. 제조된 gibbsite suspension의 누적 농도 변화 관찰에 의한 침강 시간의 조정 후 정적 침강 분리에 의해 nm 크기별로 분리된 TEM 시편을 만들 수가 있었다. 시편의 전체적인 양상은 SEM으로 관찰하였고 개개 입자들의 morphology 는 TEM으로 분석하였다. 또한, 공정 과정 중의 상변화 가능성을 검토하기 위해 XRD 분석을 실시하였다.
There is great requirement on the TEM specimen preparation method with particle size selectivity as a prerequisite for the quantitative structure analysis on the materials such as gibbsite powder, which generally forms a large agglomerate and shows a variation of transition process depending on their sizes. In this experiment, we made an attempt to give a methodology for the TEM specimen preparation of powder with the size selectivity. After mixing 1 wt% gibbsite powder with ethanol solvent, gibbsite suspension was prepared by application of ball-milling and ultrasonification with addition of 0.25 vol% dispersion agent, Darvan C, which was diluted into distilled water by the ratio 1:19. Appling the static sedimentation method to gibbsite suspension after estimation of the sedimentation time by the measurement of accumulative concentration variation, we acquired TEM specimens with well-dispersed and size selected gibbsite particles in nm scale. Overall picture of each sample was taken by SEM and morphology of each dispersed particle was imaged by TEM. Raw and processed gibbsite powders were also examined by XRD to investigate whether they were suffered from phase change during the process or not.
Brindley GW, Choe JO : The reaction series, gibbsite → chi alumina → kappa alumina → corundum. The American Mineralogist 46(7/8) : 771ー785, 1961
Cesteros Y, Salagre P, Medina F, and Sueiras JE : A new route to the synthesis of fine-grain gibbsite. Chem. Mater 13 : 2595-2600, 2001
Hwang KY : Size separation (Review paper). J Korean Institute Mineral Mining Engneers 20 : 44-54, 1983
Ingram-Jones VJ, Slade RCT, Davies TW : Dehydroxylation sequences of gibbsite and boehmite: Study of differences between soak and flash calcination and of particle-size effects. J Mater Chem 6(1) : 73-79, 1996
Ingram-Jones VJ, Slade RCT, Davies TW : Dehydroxylation sequences of gibbsite and boehmite: Study of differences between soak and flash calcination and of particle -size effects. J Mater Chem 6(1) : 73-79, 1996
Kim YJ, Jeung JM, Lee YB, Lee SJ, Song JH : An investigation of in situ TEM heating experiments of powder samples. Korean J Electron Microscopy 31(4) : 315-323, 2001
McCabe WL, Smith JC, Harriott P : Unit operations of chemical engineering. McGraw Hill College Div, Newyork, pp. 123-128, 1993
Seyssiecq I, Veesler S, Boistelle R, Lamerant JM : Agglomeration of gibbsite Al $(OH)_3$ crystals in Bayer liquors. Influence of the process parameters-the case of gibbsite crystals agglomeration in bayer liquors. Chemical Engineering Science 53(12) : 2177-2185, 1998
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