本研究想製作粒徑小於100nm的α-Al2O3生坯，以供未來製作微米級氧化鋁（陶瓷）之用。利用晶徑接近相變臨界晶徑(dcθ=25nm)之θ-Al2O3粒體，模擬核殼技術於其粒體外包覆三種不同厚度的PEG(Polyethylene glycol)膜，其厚度為2、2.36、2.7nm，得到模擬θ-Al2O3(Core)@PEG(Shell)核殼粉末。再分別以464、438、412、387MPa單軸加壓成含PEG的θ-Al2O3生坯。所有試樣均先以DTA觀察其除去PEG及θ-至α-Al2O3相變的溫度。研究分成兩部分觀察：第一部分由室溫加熱至600℃持溫30分鐘得到去除PEG之θ-Al2O3生坯。以BET觀察晶徑粗化與生坯相對理論密度及相變溫度關係，以找出有沒有可能得到θ-Al2O3粒體變化不大，但粒體各自分離，堆積密度又高的θ-Al2O3生坯；第二部分把θ-Al2O3(Core)@PEG(Shell)生坯，或已去PEG之θ-Al2O3生坯，在θ-至α-Al2O3相變開始溫度1150℃下，以不同持溫時間進行煆燒，製作α-Al2O3生坯。得到的生坯再以BET、XRD、SEM觀察生坯內粉末的α-Al2O3生成量與粒徑，及坯體堆積密度變化。以瞭解製作粒徑<100nm 之α-Al2O3生坯的方法。
研究結果顯示去除掉PEG後的θ-Al2O3生坯其生坯堆積密度介於50-54%理論密度。密度越高比表面積值也越大，且相變溫度也越高，並高於未加PEG的試樣。說明可製作與原θ-Al2O3粉末粒徑相近，同時粒體各自分離的θ-Al2O3生坯。第二部分利用第一部分得到最佳高密度細晶粒的θ-Al2O3生坯條件，得到的α-Al2O3生坯發現，藉由α-Al2O3生成量與XRD-Scherrer diameter及比表面積分析得知，相變後的α-Al2O3晶徑絕大部份停留在50.5-55.5nm間。蠕蟲現象在α-Al2O3生成量超過70%後開始發生。故要製作出晶徑小於100nm的α-Al2O3生坯，可採用模擬θ-Al2O3@2nmPEG技術製作的θ-Al2O3生坯，將及熱處理，得到α-Al2O3生坯。此時可控制α-Al2O3的生成在70-80%。所得之生坯密度可達60%理論密度。

Modified θ-Al2O3@PEG powders were prepared by mixing θ-Al2O3 powders with PEG so as to form a 2nm thickness PEG coating on the θ-Al2O3 particles. The core-shell powder was used to prepare nano-sized α-Al2O3 compacts. The presence of PEG in θ-Al2O3 compacts provided the function to fabricate a compact in which the original θ-Al2O3 particles would be apart individually. The α-Al2O3 compacts then were achieved by subsequent thermal treatments following the size character that occurs to α-Al2O3 during θ- to α- Al2O3 phase transformation. The α-Al2O3 compacts thus obtained possess of phase purity 70-80% α-Al2O3, crystallite size 50-100nm in diameter, and relative density > 60 % of T. D.

[1] W. H. Gitzen (edited), Alumina as a Ceramic Material, The American Ceramic Society, 2006.
[2] E. Dorre and H. Hubner, Alumina：Processing, Properties, and Applications , Springer, 1984.
[3] Z. Q. Wei, T. D. Xia, L. F. Bai, Efficient preparation for Ni nanopowders by anodic arc plasma [J ]. Mater Lett ,(60), 766, 2006.
[4] H. G. Zheng, J. Liang, J. H. Zeng, Preparation of nickel nanopowders in ethanol water system ( EWS) [J ]. Mater Res Bull, (36), 947, 2001.
[5] 許珂敬 ,楊新春 ,許煜汾, “表面活性劑在膠體製備過程中的作用[J]. ”中國有色金屬學報, 8 ,(2) ,560, 1998.
[6] T. G. Langdon,“Review Paper Superplastic-like Flow in Ceramics： Recent Development and Potential Application,” Ceramics International, 19, 279-286, 1993.
[7] 楊榮澤, “20 至 100 nm α-Al2O3 晶粒的熱力學特性, ” 成功大學資源工程學系碩士學位論文, 2003.
[8] 郝成偉, 吳伯麟, 李繼彥. “聚乙二醇分散劑對高纯超细 α-Al2O3 製備的影響. ”無機化學學報, 2007.
[9] R. S. Zhou and R. L. Snyder, “Structures and transformation mechanisms of the η, γ and θ transition aluminas, ” Acta Crystallographica Section B: Structural Science, 47, (5), 617-630, 1991.
[10] K. Wefers and C. Misra, “Oxides and hydroxides of aluminum, ” Alcoa Technical Paper, no. 19, Alcoa laboratories, Pittsburgh, 47, 1987.
[11] J. L. McArdle and G. L. Messing, "Transformation, microstructure 63 development, and densification in α-Fe2O3-seeded boehmite-derived alumina," Journal of the American Ceramic Society, 76, (1), 214- 222, 1993.
[12] I. Levin and D. Brandon, "Metastable alumina polymorphs: crystal structures and transition sequences," Journal of the American Ceramic Society, 81, (8), 1995-2012, 1998.
[13] H. Saalfeld, " The dehydration of gibbsite and the structure of a tetragonal γ- Al2O3," Clay Minerals Buletinl, 3, (19), 249-56, 1958.
[14] J. Kohn, G. Katz, and J. Broder, "Characterization of β-Ga2O3 and its alumina isomorph, θ-Al2O3," American Mineralogist, 42, 398, 1957.
[15] S. Geller, "Crystal structure of β‐Ga2O3," The Journal of Chemical Physics, 33, (3), 676-684, 1960.
[16] M. Munro, " Evaluated material properties for a sintered alpha ‐ alumina," Journal of the American Ceramic Society, 80, (8), 1919-1928, 1997.
[17] Y.-M. Chiang, D. P. Birnie, W. D. Kingery, and S. Newcomb, “Physical ceramics: principles for ceramic science and engineering,” John Wiley & Sons, New York, 1997.
[18] Badkar P. A. and Bailey J. E., “The mechanism of simultaneous sintering and phase transformation in alumina,” Journal of Materials Science, 11, 1794-1806, 1976.
[19] K. J. Morrissey, K. K. Czanderna, C. B. Carter, and R. P. Merrill, “Growth of α-Al2O3 within a transition alumina matrix,” Communications of the American Ceramic Society, C88-C90, 1984.
[20] T. C. Chou and T. G. Nieh, “Nucleation and concurrent anomalous grain growth of α-Al2O3 during γ→α pahse transformation,” Journal of the American Ceramic Society, 74, (9), 2270-2279, 1991.
[21] T. C. Chou and T. G. Nieh , “Interface-controlled phase transformation and abnormal grain growth of α-Al2O3 in thin γ-alumina films,” Thin Solid Films, 221, (2), 89-97, 1992.
[22] J. R. Wynnyckyj and C. G. Morris, “A shear-type allotropic transformation in alumina,” Metallurgical transactions B, 16B, 345-353, 1985.
[23] F. W. Dynys and J. W. Halloran , “Alpha alumina formation in alum-derived gamma alumina,” Journal of the American Ceramic Society, 65, (9), 442-448, 1982.
[24] F. W. Dynys and J. W.Halloran, “Alpha alumina formation in Al2O3 gels,” pp. 142-151 in Ultrastructure Processing of Ceramics, Glasses and Composites, Edited by L. L. Hench and D. R. Ulrich. John Wiley and Sons, New York, 1984.
[25] Y. Yang, Y. C. Wu, Y. Li, and P. Cui, “Preparation of ultrafine powders by thermal decomposition of AACH at low temperature,” The Chinese Journal of Process Engineering, 2, (4), 325-329, 2002.
[26] P. C. Yu, R. J. Yang, Y. T. Chang, and F. S. Yen, “Fabrication of nano-scaled α-Al2O3 crystallites through heterogeneous precipitation of boehmite in a well-dispersed θ-Al2O3–suspensions,” Journal of the American Ceramic Society, 90, (8), 2340-2346, 2007.
[27] H. L. Wen, Y. Y. Chen, F. S. Yen, and C. Y. Huang, “Size characterization of θ- and α-Al2O3 crystallites during phase transformation,” Nanostructured mater, 11, (1), 89-101, 1999.
[28] H. L. Wen and F. S. Yen, “Growth characteristics of boehmite-derived ultrafine theta and alpha-alumina particles during phase transformation,” Journal of Crystal Growth, 208, 696-708, 2000.
[29] M. L. Panchula. and J. Y. Ying, “Mechanical synthesis of nanocrystalline α-Al2O3 seeds for enhanced transformation kinetics,” Nanostructured Mater, 9, 161-164, 1997.
[30] G. Carturan, R. D. Maggio, M. Montagna, O. Pilla, and P. Scard, “Kinetics of phase separation and thermal behavior of gel-derived Al2O3 doped by Cr2O3: an X-ray diffraction and fluorescence spectroscopy study,” Journal of Materials Science, 25, 2705-2710, 1990.
[31] S. Rajendran, “Production of ultrafine alpha alumina powders and fabrication of fine grained strong ceramics,” Journal of Materials Science, 29, 5664-5672, 1994.
[32] R. M. Laine, J. C. Marchal, H. P. Sun, and X. Q. Pan, “Nano-α-Al2O3 by liquid-feed flame spray pyrolysis,” Nature Mater, 5, 710-712, 2006.
[33] G. P. Johnston, R. Muenchausen, and D. M. Smith, “Reactive laser ablation synthesis of nanosize alumina powder,” Journal of the American Ceramic Society, 75, (12), 3293-3298, 1992.
[34] J. S. Reed, “Principles of ceramics processing, ” John Wiley & Sons, New York, 1995.
[35] M. N. Rahaman, L. C. Jonghe, and M. Y. Chu, "Effect of green density on densification and creep during sintering," Journal of the American Ceramic Society, 74, (3), 514-519, 1991.
[36] 李玄閔, “不同粒徑分佈與凝聚狀態之 α-氧化鋁粉末的成型及燒結行為,”成功大學資源工程學系碩士學位論文, 2004.
[37] A. Krell, P. Blank, H. Ma, T. Hutzler, and M. Nebelung, "Processing of high‐ density submicrometer Al2O3 for new applications," Journal of the American Ceramic Society, 86, (4), 546-53, 2003.
[38] A. Krell and J. Klimke, "Effects of the Homogeneity of Particle Coordination on Solid‐State Sintering of Transparent Alumina," Journal of the American Ceramic Society, 89, (6), 1985-1992, 2006.
[39] 顧峰 ,沈悅 ,徐超 ,等.分散劑聚合度對奈米氧化鋁粉體特性的影響[J].功能材料, 36, (2), 318, 2005.
[40] 葉云 ,李巧玲 ,景红霞 ,等.分散劑對奈米鐵酸鹽製備的影響及TEM表徵[J].電子顯微學報, 25(增刊), 75, 2006.
[41] 鄒同征, 涂江平, 夏正志, 等.聚乙二醇為分散劑的沉澱法製備 IF2MoS2 [J].無機化學學報, 21, (8), 117, 2005.
[42] 劉付勝聰 ,肖漢寧 ,李玉平 ,等. 奈米TiO2表面吸附聚乙二醇及其分散稳定性的研究[J]. 無機材料學報, 20, (2), 310, 2005.
[43] 朱曉文 ,李登好.聚電解質分散劑對超细氧化鋁懸浮液穩定性的影響[J].淮阴工學院學報, 15, (1), 50, 2006.
[44] X. H. Liu, "An improvement on sol-gel method for preparing ultrafine and crystallized titania powder." Materials Science and Engineering, A289, (1-2), 241-245, 2000.
[45] B. D. Cullity, Elements of X-ray Diffraction, Addison-Wesley Publishing Company, Inc. 2nd Ed., London, 1978.
[46] C. S. Nordahl and G. L. Messing, “Sintering of α-Al2O3-seeded nano crystalline γ-Al2O3 powders,” Journal of the European Ceramic Society, 22, 415-422, 2002.
[47] P. C. Yu and F. S. Yen “On the High Pure Alumina Composite Powder for Sintering at 1400oC,A Preliminary Investigation” Key Engineering Materials, 313, (July), 59-62, 2006.