中文摘要
奈米級微粉與傳統粉體相比，容易在生產的過程中產生嚴重的凝聚現象，影響之後的燒結行為。為了使微粉能達到充分的解凝，在粉體前處理的程序上，適度地加以研磨是必須的。然而，研磨過程中磨屑的存在難以避免，因此，本研究想瞭解不同的解凝效果以及系統中的磨屑，會如何影響氧化鋁微粉的燒結行為。
實驗過程以高純度但凝聚嚴重之  氧化鋁微粉當作起始原料，選用氧化鋯磨球，利用高能攪拌磨機 (attritor) 進行球磨，以不同的研磨條件，達到各種解凝的效果以及不同的氧化鋯磨屑含量，之後利用不同的成型壓力以單軸乾壓的方式，將各系列粉體製作成相對密度皆達 47% 的生坯，比較其燒結行為的演變。
研究結果發現，研磨後可將凝聚體磨散，其中打散的單離粒子大小約為 150 ~ 200 nm，而透過不同的研磨參數可獲得不同的解凝效果以及氧化鋯磨屑量 (約0 ~ 3 wt%)。在燒結初中期的時候，氧化鋯磨屑的影響較為顯著，其延遲了燒結收縮的起始溫度以及提升整體緻密速率；到了燒結末期，粉末的解凝效果則有較顯著的影響，因為凝聚體之間的孔洞若不能排除，則最終密度無法提升。在沒有氧化鋯磨屑的影響之下，與未解凝處理的起始粉相比，400 rpm/0.5 h 系列的稍微解凝，雖不能有效提昇燒結體密度，但卻因為 intragranular 以及 intergranular pore 的數量比例改變，而能夠減緩晶粒的大幅成長。
與前人研究相比，本研究中少量氧化鋯磨屑即可有效抑制燒結後期的晶粒成長，但對凝聚體造成之異常晶粒成長卻無法抑制。在解凝效果相近的條件下，於 1500℃ 前，磨屑含量較高的系統，其晶粒略小於磨屑含量較少的系統；1500℃後，磨屑含量高的系統，因氧化鋯磨屑容易粗化而結晶為 t 相，減少氧化鋯分佈於氧化鋁晶粒的數量，最後抑制晶粒成長的效果反而不如磨屑含量少的系統。
研磨 600 rpm 轉速系列的粉體，雖然解凝效果有效提升，但因凝聚體與單離粒子的體積比例接近，其氧化鋯磨屑僅能抑制單離粒子的晶粒成長，而凝聚體則透過晶界擴散遷移發展成異常晶粒成長，故呈現出晶粒成長兩極化的微結構。

ABSTRACT
Compared with traditional powder, excessive agglomeration of nano-powder can easily occur during production. For the purpose of deagglomeration, it is necessary to mill powder appropriately at the preceding process. It is difficult to avoid the wear debris during milling. Therefore, this study hopes to understand the influences of
deagglomeration and wear debris on the sintering of fine alumina powder.
The starting material used in this study was fine -alumina powder that has high purity but excess agglomerates. The starting powder was milled by attritor with zirconia media. The different degree of deagglomeration and quantity of zirconia wear debris was obtained with various milling parameters. Every series of powder was pressed uniaxially to prepare green body with at least 47 % relative density by different forming pressure and the sintering behavior of the green body was also examined.
The result shows that agglomerates are broken up after attrition milling and the separate particles are about 150 ~ 200 nm, and the amount of zirconia wear debris is about 0 ~ 3 wt%. The zirconia wear debris affects the early stage sintering behavior more obviously. It delays onset temperature of sintering shrinkage and increases the densification rate. However, the deagglomeration affects the final sintering more apparently. The final density of sintering bulk is limited because of the existence of pores among agglomerates. Without considering the influence of zirconia wear debris, the bulk density of 400 rpm/0.5 h series that has slight deagglomeration can’t increase effectively but the extreme grain growth is delayed.
Compared with the past research, less amount of zirconia wear debris can hinder effectively grain growth of alumina during final sintering. But it can’t hinder abnormal grain growth. On the same degree of deagglomeration condition, the grain size of more zirconia wear debris system is smaller than of less zirconia wear debris system below 1500℃ sintering. However, the grain-growth hindrance ability of more zirconia system is inferior to less zirconia system above 1500℃ because the amount of ZrO2 inclusions (more zirconia system) distributed over alumina grains was decreased due to earlier transformation to t-phase during coalescence of zirconia particles.
Powder milled by 600 rpm has the better degree of deagglomeration, but the proportion of agglomerates and separate particles is close. Zirconia debris can hinder grain growth of separate particles. However, agglomerates can evolve abnormal grain growth which results in two opposing extremes of the microstructure by grain boundary migrating.

參考文獻
1.張立德、牟季美，奈米材料和奈米結構，滄海書局，(2002)。
2.J. S. Reed, Introduction of the Principles of Ceramic Processing, John Wiley and Sons, New York, (1995).
3.R. Morrell, Handbook of Properties of Technical and Engineering Ceramics, Part 2 Data Reviews-Selection I: High-Alumina Ceramic, National Physical Laboratory, HMSO, London, (1987).
4.C. Klein and C. S. Hurlbut, Jr., Manual of Mineralogy, John Wiley and Sons, New York, (1993).
5.R. L. Coble, “Sintering Crystalline Solids: II, Experimental Test of Diffusion Models in Powder Compacts,” J. Appl. Phys., 32, 793-799, (1961).
6.M. F. Ashby, “A First Report on Sintering Diagrams,” Acta Metal., 22, 275-289 (1974).
7.W. D. Kingery, H. K. Bowen, and D. R. Uhlmann, Introduction to Ceramics, John Wiley and Sons, New York, (1975).
8.F. F. Lange and B. I. Davis, “Sinterability of ZrO2 and Al2O3 Powders: The Role of Pore Coordination Number Distribution,” in Science and Technology of Zirconia II, Ed. By N. Claussen, M. Ruble, and A. H. Heuer, Am. Ceram. Soc., (1984.)
9.H. P. Cahoon and C. J. Christensen, “Sintering and Grain Growth of Alpha-Alumina,” J. Am. Ceram. Soc., 39, 337-344, (1956).
10.P. L. Chen and I. W. Chen, “Sintering of fine Oxide Powders: II, Sintering Mechanisms,” J. Am. Ceram. Soc., 80 [3], 637-645, (1997).
11.M. N. Rahaman, Ceramic Processing and Sintering, M. Dekker, New York (1995).
12.J. G. Li and X. Sun, “Synthesis and Sintering Behavior of a Nanocrystalline -Alumina Powder,” Acta Mater, 48 [12], 3103-3112, (2000).
13.C. R. Veale, Fine Powders: Preparation, Properties and Uses, Applied Science Publishers Ltd, London, 1972.
14.J. P. Smith and G. L. Messing, “Sintering of Bimodally Distributed Alumina Powders,” J. Am. Ceram. Soc., 67 [4], 238-242, (1984).
15.G. L. Messing and J. L. McArdle, “Seeding with -alumina for Transformation and Microstructure Control in Boehmite-derived -alumina,” J. Am. Ceram. Soc., 69 [5], c98-c101, (1986).
16.P. A. Badkar and J. E. Bailey, “The Mechanism of Simultaneous Sintering and Phase Transformation in Alumina,” J. Mater. Sci., 11, 1794-1806, (1976).
17.G. L. Messing and J. L. McArdle, “Transformation, Microstructure Development, and Densification in -Fe2O3 Seeded Boehmite-Derived Alumina,” J. Am. Ceram. Soc., 76 [1], 214-222, 1993.
18.王一峰，-Al2O3 微粉燒結行為的觀察，成功大學資源系碩士論文，(2002)。
19.J. W. Halloran, “Role of Powder Agglomerates in Ceramic Processing,” in Advances in Ceramics, 9, Forming of Ceramics, Eds. J. A. Mange and G. L. Messing, Am. Ceram. Soc., (1984).
20.F. D. Dynys and J. W. Halloran, “Influence of Aggregates on Sintering,” J. Am. Ceram. Soc., 67 [9], 596-601, (1984).
21.R. T. Tremper and R. S. Gordon, “Agglomeration Effects on the Sintering of Alumina Powders Prepared by Autoclaving Aluminum Metal,” in Ceramic Processing before Firing, Eds. G. Y. Onoda and L. L. Hench, Wiley, New York, (1978).
22.P. J. Jorgensen and J. H. Westbrook, “Role of Solute Segregation at Grain Boundaries During Final-Stage Sintering of Alumina,” J. Am. Ceram. Soc., 47 [7], 332-338, (1964).
23.N. J. Shaw and R. J. Brook, “Structure and Grain Coarsening During the Sintering of Alumina,” J. Am. Ceram. Soc., 69 [2], 107-110, (1986).
24.J. Wang and R. Raj, “Estimate of the Activation Energies for Boundary Diffusion from Rate-Controlled Sintering of Pure Alumina, and Alumina Doped with Zirconia or Titania,” J. Am. Ceram. Soc., 73 [5], 1172-1175, (1990).
25.R. Majumdar, E. Gilbart, and R. J. Brook, “Kinetics of Densification of Alumina-Zirconia Ceramics,” Br. Ceram. Trans. J., 85 [5], 156-160, (1986).
26.F. F. Lange and M. M. Hirlinger, “Hindrance of Grain Growth in Al2O3 by ZrO2 Inclusions,” J. Am. Ceram. Soc., 67 [5], 164-168, (1984).
27.S. Hori and R. Kurita, “Suppressed Grain Growth in Final-Stage Sintering of Al2O3 with Dispersed ZrO2 Particles,” J. Mat. Sci. Lett., 4, 1067-1070, (1985).
28.Y. M. Pan and R. A. Page, “Role of Zirconia Addition in Pore Development and Grain Growth in Alumina Compacts,” J. Mater. Res., 14 [12], 4602-4614, (1999).
29.B. W. Kibbel and A. H. Heuer, “Rippening of Inter- and Intragranular ZrO2 Particle in ZrO2-Toughened Al2O3,” in Advances in Ceramics, Vol. 12, Science and Technology of Zirconia II., Ed. by N. Claussen, M. Ruble, and A. H. Heuer, Am. Ceram. Soc., (1984).
30.B. W. Kibbel and A. H. Heuer, “Exaggerated Grain Growth in ZrO2-Toughened Al2O3,” J. Am. Ceram. Soc., 69 [3], 231-236, (1986).
31.F.F. Lange and D. J. Green, “Effect of Inclusion Size on the Retention of Tetragonal ZrO2: Theory and Experiments,” in Advances in Ceramics, Vol. 3, Science and Technology of Zirconia, (1981).