臺灣博碩士論文加值系統

經由anatase-TiO2 以及石墨混合作為前驅物,經由高能球磨促使二氧化鈦粉末與石墨產生carbothermic 還原反應,在低壓流體床中與氮氣反應,可生成奈米氮化鈦粉末.高能球磨所造成的晶粒細化,表面積增大以及缺陷濃度的增加以及粉末的內應力提昇皆有助於氮化鈦的形成
由本實驗結果發現,粉末的晶粒會隨著球磨時間的增加而減小並且隨球磨時間的增加所造成的強烈撞擊使得反應的能力提高而大幅降低了反應溫度.未經球磨的粉末由實驗證明無法藉由形成carbothermic 還原反應而形成氮化鈦.
本實驗所產生的奈米氮化鈦粒徑經由穿透式電子顯微鏡的觀察大約為42nm

Nano-structure TiN powders were prepared by using anatase-TiO2 and graphite mixtures as the precursor. Prior to thermal conversion, the mixture of TiO2 and graphite was milled in a high energy attritor to enhance the validity of carbothermic reduction. The nano-TiN powders were thermal converted by introducing N2 into a low pressure circulated fluidized-bed reactor which was previously evacuated to the pressure around 10-1 torr
The formation of TiN compound is greatly enhanced by high-energy milling due to the reduced crystallite size, large grain boundary area, presence of amorphous phases and the increased defect concentration in the powder reactants given by the high-energy milling.
Crystallites size of the powder mixtures decreased as increasing of milling time. The nano-TiN formation can be accomplished at a relatively low reaction temperatures and short reaction time via severe milling of TiO2 + graphite mixtures.
The experiment results evidenced that the carbothermic reduction could not be occurred if the powder mixture of TiO2 + graphite had not been undergone a severe milling

Abstract………………………………………………………………..…2
1. Introduction………………………………………………..………….1
2. Literature review……………………………………………..……...4
2.1 The fluidization phenomenon………………………...………..4
2.2 Mechanical Alloying (MA)……………………………...…….5
2.2-1 Process Control Agent (PCA)………………...………7
2.3 Crystallite size and internal strain…..........................................8
2.4 Carbothermic reduction……………………………………......11
2.4-1 Comparison of the reaction sequence with thermodynamic predictions…………………………..13
3. Experimental Procedures……………………………….….…………15
3.1 Mechanical Alloying of the Starting Powders…………..……..15
3.2 Thermal conversion………………………………...………….16
3.3 X-ray Analysis……………………………………...………….17
3.4 Scanning Electron Microscope Observation……………..……17
3.5 Transmission Electron Microscope Observation………..…….18
4. Result and discussion………………………………………….……..19
4.1 Effect of the milling time………………………………………19
4.2 Crystallite sizes and internal strain……………….……………20
4.3 X-ray analysis………………………………………………….21
4-3-1. Effect of temperature and milling time on the structures………………………………………...……21
4.3.2 Reacting chain of carbothermic reduction………..…….24
4.4 TEM and SEM micrographs…………………………..……….25
4.4-1 Influence of milling time……………………………….25
4.4-2 Lattice parameter determination of TiN………………..26
4.4-3 TEM micrographs………………………………………27
4.5 Conclusions……………………………………………………28
5. Reference……………………………………………………………..30

[1] N. J. Whlham, Minerals Eng. 9(12) (1996) 1189.
[2] N.Malhourourx-Gaffet and E. Gaffet, J. Alloys & Compounds 198(1993) 143.
[3] E. Gaffet and N. Malhourourx-Gaffet, ibid. 205 (1994)27.
[4] Y. Chen, J.Mater. Sci. Letter 16(1997) 37.
[5] Idem., Scripta Mater. 36(9) (1997) 989.
[6] Y. Chen, T. Hwang, M. Marsh and J. S. Williams. Metall. Mater. Trans. 28A(5) (1997)1115.
[7] E. Gaffet, M. Abdellaoui and N. Malhourourx-Gaffet. Mater. Trans. JIM.36(2) (1995)198.
[8] N. Mahourourx-Gaffet and E. Gaffet. J. Alloys & Compounds 198 (1993) 143.
[9] J. S. Benjamin, Metall. Trans., 1(1970)2943.
[10] B. S. Murty, M. D. Naik, S. Ranganathan and M. Mohan, Mater. Forum., 16(1992)19.
[11] Y. F. Zhang, L. Lu and S. M. Yap, Journal of Materials Processing Technology, 89-90(1999)260.
[12] B. D. Cullity and S. R. Stock, “Elements of X-ray Diffraction” Prentice Hall, New Jersey, 2001.
[13] J. L. Murray H.A. Wriedt, O-Ti phases Diagram, in: T.B. Massalski, H. Okamoto, P.R. Subramania and L. Kacprzak, (Ed.). Binary Alloy Phase Diagrams, ASM International, Materials Park, OH, 1990, pp. 2924-2927.
[14] P.G. Wahlbeck, P.W. Gilles, J.Am. Ceram. Soc. 49 (4) (1965) 180-183.
[15] S.Andersson, B. Collen, U. Kuylenstierna, A. Magneli, Acta Chem. Scand. 11(10) (1957) 1641-1652.
[16] L.A. Bursill, B.G. Hyde, O. Terasaki, D. Watanabe, Phil. Mag. 20 (1969) 347-359.
[17] L.-M. Berger, J. Hard Mater. 3 (1) (1992) 3-15.
[18] G.V. White, K.J.D. Mackenzie, I.W.M. Brown, M.E. Bowden, DSIR Chemistry, Journal of amterials Science, New Zealand, 27 (1992) 4294-4299
[19] C. E. Weeks and F.E.Block, US Bur. Mines Bull. 605 (1963)
[20] R.A.Robie, B. S. Hemingway and J. R. Fisher, US Geol. Surv. Bull. 1452 (1978)