| Summary: | 碩士 === 國立成功大學 === 資源工程學系碩博士班 === 93 === This research prepared nano α-Al2O3 powders by mixing aqueous aluminum nitrate solutions and oleic acid. Water-in-oil (w/o) type emulsions were obtained by mixing different ratios of aqueous aluminum nitrate solutions and oleic acid with high speed stirring mixer. The emulsions were heated with plate heater at 180℃ to remove water in the mixture until got the dark brown alumina precursor. The precursors were calcined at the temperatures of 1000℃, 1050℃, 1100℃ for 2 h to form nano α-Al2O3 powders. These nano α-Al2O3 powders were identified by X-ray diffraction (XRD), specific surface area measurement (BET), scanning electron microscope (SEM) and transmissional electron microscope (TEM). The X-ray diffraction patterns revealed that diaspore (β-AlOOH) might be formed during dewatering process. The specific surface areas of α-Al2O3 powders calcined at 1000℃ for 2 h were in the range of 15.5∼21 m2/g and calculated particles size were between 71∼97 nm. As the content of aqueous aluminum nitrate solutions increased relative to oleic acid, the size of α-Al2O3 powders were enlarged as the calcination temperature increasing. The particles size of α-Al2O3 powders obtained from 1000℃ calcinations for 2 h with the ratios of aqueous aluminum nitrate solutions and oleic acid from 8:2 to 5:5 were ranging from 40 to 60 nm by SEM observation. The TEM photos indicated that as the ratio of aqueous aluminum nitrate solution and oleic acid was 5:5, the particle size distribution was uniform spherical shape and the average size was near 50 nm.
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