臺灣博碩士論文加值系統

Gibbsite在工業上主要做為生產氧化鋁產品的重要原料。然而隨著其粉末粒徑越小以及片狀外型的具備，在複合材料上有更高的應用層面與效果，單價也隨之大幅提高。如能突破現今技術，以低成本生產出較目前商業上次微米級產品更細的奈米級片型gibbsite粉末，勢必能成為更高階應用與高單價的產品。因此本研究欲以χ-Al2O3為原料，利用熱水溶液法來合成奈米級的片狀gibbsite粉末。
本研究藉由攪拌、球磨、珠磨以及珠磨+離心四種不同細化方式取得不同粒度的χ-Al2O3，調配成pH～4.5，固含量1 wt%的漿料作為原料，在100℃熱水溶液環境中合成gibbsite晶體。探討gibbsite生成與原料粒徑、熱水處理時間的關係，試著找出生成機制並觀察合成粉末的外型。研究結果顯示：（1）Gibbsite的生成量有隨原料粒徑減小而增加的趨勢，且主要受小粒徑（＜200 nm）χ-Al2O3的多寡影響。生成量與熱水處理時間呈一指數成長的關係。（2）此環境下χ-Al2O3原料以一類似熱水法中溶解-析出的機制生成gibbsite。（3）此法可合成結晶性良好且單離的gibbsite晶體，以scherrer formula計算出其（002）晶面厚度為31 nm。整體粉末具片狀外型，片面直徑約300～600 nm，厚度在50 nm左右。

Traditionally, gibbsite (Al(OH)3) is the most important raw material for producing alumina powders in industry. Moreover, it has more advanced applications in composite materials and higher price when the particle size was reduced and the plate-like shape was possessed. It is going to be higher level application and higher unit price powders if the low-cost ways that can manufacture gibbsite platelets with particle size thinner than the submicron-scaled commercial powders.
In this study, χ-Al2O3 was used as raw material to synthesis nano-scaled gibbsite platelets by hydrothermal treatment. Four kinds of χ-Al2O3 slurries with different particle size were obtain by different fining treatments: stirring, ball milling, pearl milling, and pearl milling + centrifuge treatment. After dilution, χ-Al2O3 slurries with pH~4.5 and solid contain 1 wt% were obtained as the starting materials. And then, gibbsite crystallites were synthesized under hydrothermal conditions at 100℃. The relationship among the formation of gibbsite crystallites, particle size of the raw materials and duration of the hydrothermal treatment were discussed. Further, the particle size and shape of the produced powders were investigated and the synthesized mechanism was tried to find out. The results showed that: (1) The formation of gibbsite crystallites tended to increase with the reduction of the particle size of starting materials, and it was mainly dominated by the amount of theχ-Al2O3 crystallites with small particle size (＜200 nm). The formation of gibbsite crystallites showed a exponential increase with the durations of the hydrothermal treatment. (2) Under the hydrothermal treatments, the mechanism of gibbsite crystallites synthesis from χ-Al2O3 is similar to the mechanism of dissolution-precipitation. (3) Mono-dispersed and well crystallized gibbsite crystallites with mean crystallite size 31 nm calculate from the (002) XRD reflection by Scherrer formula can be synthesized in this study. From the investigations of TEM and SEM micrographs, the synthesized gibbsite powders possess plate-like shape and whose crystallite size in diameter and in thickness are 300～600 nm and about 50 nm, respectively.

摘要 I
Abstract II
目錄 IV
圖目錄 VII
表目錄 XI

第一章 緒論 1
1.1 前言 1
1.2 研究目的 2

第二章 理論基礎與前人研究 3
2.1 Gibbsite與χ-Al2O3結構 3
2.1.1 Gibbsite的結構 3
2.1.2 χ-Al2O3的結構 3
2.2 熱水法[22] 4
2.2.1 熱水法簡介 4
2.2.2 熱水法優點 4
2.2.3 熱水法長晶理論與機構 5
2.3 Gibbsite溶解度曲線 6
2.4 熱水系統合成gibbsite的溫度上限 7
2.5 合成gibbsite相關前人研究 7

第三章 實驗步驟及方法 15
3.1 實驗構想與設計 15
3.2 實驗步驟與流程 15
3.2.1 χ-Al2O3粉末之獲得與細化處理 15
3.2.2 熱水處理合成gibbsite晶體 16
3.3 特性分析 16
3.3.1 粉末結晶相分析 16
3.3.2 粉末半峰寬量測及晶徑分析與計算 16
3.3.3 粒度分佈量測 17
3.3.4 AA鋁離子濃度測定 17
3.3.5 BET比表面積測定 18
3.3.6 DTA熱差分析 18
3.3.7 Gibbsite生成量之定量分析 18
3.3.8 顯微結構分析 18

第四章 結果與討論 22
4.1 原料χ-Al2O3粒徑對gibbsite生成影響 22
4.1.1 不同粒徑原料經熱水處理一天 22
4.1.2 隨熱水處理時間gibbsite的生成量變化 25
4.2 Gibbsite之生成機制探討 27
4.2.1 Gibbsite的析出 27
4.2.2 原料χ-Al2O3與所合成gibbsite晶體粒徑變化 27
4.2.3 熱水合成gibbsite之可能機制 35
4.3 合成粉末性質分析比較 38
4.3.1 DTA/TG分析 38
4.3.2 XRD繞射分析 38
4.3.3 顯微影像觀察 38
4.4 綜合討論 43

第五章 結論 45

參考文獻 46

Appendices 50

1.A. R. Hind, S. K. Bhargava and S. C. Grocott, “The Surface Chemistry of Bayer Process Solids: A Review,” Colloids Surf. A: Physicochem. Eng. Aspects, 146, 359-374 (1999).

2.J. E. G. J. Wijnhoven, “Seeded Growth of Monodisperse Gibbsite Platelets to Adjustable Sizes,” J. Colloid Interface Sci., 292, 403-409 (2005).

3.張學明, 簡文鎮, 劉邦一, “氫氧化鋁應用與分析技術,” 化工資訊與商情, NO. 5, 81-86 (2003).

4.J. C. Si, L. S. Zheng and M. X. Lu, “Application of Inorganic Composite Flame-retardant Filler in Flexible PVC,” Mater. Mech. Eng., 28, [12] 26-28 (2004).

5.J. M. Li, S. D. Wang, H. Han and A. P. Yan, “Physical and Chemical Properties of AH Filler on its Use and the Products’ Performance,” Chemical Industry and Engineering Progress, 23, [6] 635-637 (2004).

6.X. H. Chen and C. Zhang, “Ultrafine Aluminum Hydroxide Powder Prepared by Seed Crystal Decomposition,” Guizhou Science, 17, [3] 190-193 (1999).

7.P. Carty, E. Metcalfe and W. N. Annison, “The Optimization of the Smoke Suppressant and Flame Retardant Properties of Flexible PVC,” J. Appl. Polym. Sci., 41, 901-906 (1990).

8.J. C. Si, S. L. Zheng and M. X. Lu, “Suface Modifying and Applied Research of Aluminum Hydroxide,” China Powder Science and Technology, 11, [2] 15-17 (2005).

9.F. Y. Wu, G. H. Liu and G. Z. Feng, “Application and Production of Varieties Aluminium Hydroxide,” Conservation and Utilization of Mineral Resources, 6, 41-44 (2001).

10.A. A. Gusev and H. R. Lusti, “Rational Design of Nanocomposites for Barrier Applications,” Adv. Mater., 13, [21] 1641-1643 (2001).

11.A. R. Boccaccini, D. Eifler and G. Ondracek, “Determination of the Young’s Modulus of Platelet Reinforced Composite Materials,” Mater. Sci. Eng., A207, 228-233 (1996).

12.L. M. Cukrov, J. S. Robinson, B. Innes and P. G. McCormick, “A New Measure of Soft Focus Properties of Cosmetic Filler Particles,” Advanced Powder Technology Pty Ltd.

13.林天鈞，前導物之粒徑對由Gibbsite獲得α-Al2O3過程之影響，國立成功大學資源工程研究所，碩士論文，中華民國94年6月。

14.K. Wefers and G. M. Bell, “Oxide and Hydroxides of Alumina,” Technical Paper No.19, Alcoa Research Laboratories (1972).

15.B. C. Lippens and J. J. Steggerda, “Active Alumina” in Physical and Chemical Aspects of Adsorbents and Catalysts, B. GLinsen Ed., Academic Press, New York, 171 (1970).

16.H. Saalfeld, “The Sturcture of Gibbsite and the Intermediate Products of Its Dehydration,” N. Jb. Miner. Abh., 95, 1-87 (1960).

17.H. D. Megraw, Crystal Structures: A Working Approach. Saunders, Philadelphia, London, Toronto (1973).

18.K. Wefers, “Nomenclature, Preparation, and Properties of Aluminum Oxides, Oxide Hydroxides, and Trihydroxides,” in Alumina Chemicals, L. D. Hart Ed., Am. Ceram. Soc., Ohio (1990).

19.黃啟祥、林江財，氧化鋁，陶瓷技術手冊（下），683-685，中華民國產業科技發展協進會與中華民國粉末冶金協會出版。民國83年7月。

20.H. C. Stumpf, A. S. Russel, J. W. Newsome, and C. M. Tucker, “Thermal Transformations of Aluminas and Alumina Hydrates,” Ind. Eng. Chem., 42, 1398-1403 (1950).

21.G. W. Brindley and J. O. Choe, “The Reaction Series, Gibbsite→ Chi Alumina→ Kappa Alumina→ Corundum,” Am. Mineral., 46, 771 (1961).

22.W. J. Dawson, “Hydrothermal Synthesis of Advanced Ceramic Powders”, Ceram. Bull., 67, [10] 1673-1678 (1988).

23.T. Sugimoto, “Preparation of Mono Dispered Colloidal Particles,” Advances in colloid and Interface Sci., 65, 28 (1987).

24.G. Faure, Principles and Applications of Inorganic Geochemistry, Macmillan, New York (1991).

25.王明光譯，鋁的環境化學，國立編譯館出版，1999。

26.G. C. Kennedy, “Phase Relations in the System Al2O3-H20 at High Temperatures and Pressures,” Amer. J. Sci., 257, 563-573 (1959).

27.H. H. Pohland, Aluminum Oxide, Alcoa Chemie, Germany (1999).

28.C. Misra and E. T. White, “Crystallisation of Bayer Aluminium Trihydroxide,” J. Cryst. Growth, 8, 172-178 (1971).

29.C. Sweegers, H. C. de Coninck, H. Meekes, W. J. P. van Enckevort, I. D. K. Hiralal and A. Rijkeboer, “Morphology, Evolution and Other Characteristic of Gibbsite Crystals Grown from Pure and Impure Aqueous Sodium Aluminate Solutions,” J. Cryst. Growth, 233, 567-582 (2001).

30.I. Seyssiecq, S. Veesler, G. Pepe and R. Boistelle, “The Influence Of Additives on the Crystal Habit of Gibbsite,” J. Cryst. Growth, 196, 174-180, (1999).

31.A. M. Paulaime, I. seyssiecq and S. Veesler, “The Influence of Organic Additives on the Crystallization and Agglomeration of Gibbsite,” Powder Technol., 130, 345-351 (2003).

32.H. Watling, “Gibbsite Crystallization Inhibition 2. Comparative Effects of Selected Alditols and Hydroxycarboxylic Acid,” Hydrometallurgy, 55, 289-309 (2000).

33.A. M. Wierenga, T. A. J. Lenstra and A. P. Philipse, “Aqueous Dispersions of Colloidal Gibbsite Platelets: Synthesis, Characterisation and Intrinsic Viscosity Measurements,” Colloids Surf. A: Physicochem. Eng. Aspects, 134, 359-371 (1998).

34.B. D. Cullity, Elements of X-ray Diffraction, Addison-Wesley Publishing Company, Inc. 2nd Ed., London (1978).