傳統工業上以高嶺土與氧化鋁混合合成富鋁紅柱石需要極高之溫度(1500~1700°C)。固態反應法中已有足量研究可證實晶種之添加能有效降低反應所需之溫度。此研究透過在高嶺土與氧化鋁之生料系統中添加四種不同粒徑之富鋁紅柱石粉末熟料做為晶種合成富鋁紅柱石。透過DTA、XRD、TEM等儀器觀察合成富鋁紅柱石粉末過程中，晶種對反應途徑之影響以及晶種粒徑對合成反應所需生成溫度之關係。實驗結果顯示晶種可提供高嶺土相變為鋁矽尖晶石之成核位置，能使熱差分析上之生成峰強度下降。生成富鋁紅柱石的途徑可分為四種，分別為(a)未受晶種影響生成的primary mullite。(b)受晶種影響生成的primary mullite。 (c)未受晶種影響生成的secondary mullite。 (d)受晶種影響生成的scondary mullite。且晶種之添加能使反應完全所需溫度下降，其效果隨著添加之晶種粒徑變小而越明顯，當晶種粒徑為0.4 μm時，其反應完全所需溫度已降低至1400oC。

Mullite synthesized by thermal treatment of kaolinite and alumina powders has the advantage of adopting ready obtainable raw materials and thus it lowers the production thermal cost. However, its process requires higher temperature at 1500 to 1700°C. In the study, mixtures of identical raw materials, kaolin (particle size 3μm) and alumina powder (size 0.3μm) were mixed with mullite powders (used as the seed) of 0.23, 0.4, 2, and 7.5μm in diameters were used as the starting materials to fabricating mullite. The DTA profiles revealed that finer-sized mullite seeds would significantly reduce the peak height occurred at 980oC, indicating that the seed addition eventually weaken the exothermal peak of Al-Si spinel formation. And the effect increases with finer seed addition. There are four reaction routes to synthesize mullite, (a) primary mullite which is affected by mullite seed, (b) primary mullite which is not affected by mullite seed, (c) secondary mullite which is affected by mullite seed, (d)secaondary mullite which is not affected by mullite seed. When the particle size of seed is 0.4μm, the complete reaction temperature is lowered to 1400oC.

[1] I. A. Aksay and J. A. Pask, “Stable and Metastable Equilibria in the system SiO2-Al2O3,” J. Am. Ceram. Soc., vol. 58, no. 11-12, pp. 507-512, 1975.
[2] I. A. Aksay, D. M. Dabbs, and M. Sarikaya, “Mullite for Structural, Electronic, and Optical Applications,” J. Am. Ceram. Soc., vol. 74, no. 10, pp. 2343-2358, 1991.
[3] J. A. Pask, “Stable and Metastable Equilibria and Reaction in the SiO2-Al2O3 System,” Ceram Int., vol. 9, pp. 107-113, 1983 .
[4] A. R. West, Solid State Chemistry and Its Application, John Wiley＆Sons, pp. 274-281, 1986.
[5] A. K. Chakraborty and D. K. Ghosh, “Kaolinite-Mullite Reaction Series: The Development and Significance of a Binary Aluminosilicate Phase,” J. Am. Ceram. Soc., vol. 74, no. 6, pp. 1401-1406, 1991.
[6] A. K. Chakraborty and D. K. Ghosh, Comment on “Spinel Phase Formation during 980℃Exothermic Reaction in the Kaolinite-to-Mullite Reaction Series,” J. Am. Ceram. Soc., vol. 72, no. 8, pp. 1569-1570, 1989.
[7] B. Sonuparlak, M. Sarikaya, and I. A. Aksay, “Spinel Phase Formation during the 980℃ Exothermic Reaction in the Kaolinite-to-Mullite Reaction Series,” J. Am. Ceram. Soc., vol. 70, no. 11, pp. 837-842, 1987.
[8]　 G. W. Brindley and M. Nakahira, “The Kaolinite-Mullite Reaction Series: Ⅱ. Metakaolin,” J. Am. Ceram. Soc., vol. 42, pp. 314-318, 1959.
[9] G. W. Brindley and M. Nakahira, “The Kaolinite-Mullite Reaction Series: Ⅲ. The High-Temperature Phases,” J. Am. Ceram. Soc., vol. 42, pp. 319-324, 1959.
[10] A. K. Chakraborty and D. K. Ghosh, “Reexamination of the decomposition of kaolinite,” J. Am. Ceram. Soc., vol. 60, pp, 165-166, 1977.
[11] A. K. Chakraborty and D. K. Ghosh, “Reexamination of kaolinite-to-mullite reaction series,” J. Am. Ceram. Soc., vol. 61, pp. 170-173, 1978.
[12] A. K. Chakraborty and D. K. Ghosh, “Comment on‘Interpretation of the kaolinite-mullite reaction sequence from infrared absorption apectra.” J. Am. Ceram. Soc., vol. 61, pp. 90-91, 1978.
[13] A. J. Leonard, “Structural analysis of the transition phases in the kaolinite-mullite thermal sequence,” J. Am. Ceram. Soc., vol. 60, pp. 37-43, 1977.
[14] M. Bulens, A. Leonard and B. Delmon, “Spectroscopic investigations of the kaolinite-mullite reaction sequence,” J. Am. Ceram. Soc., vol. 61, pp. 81-84, 1978.
[15] H. J. Percivel, J. F. Duncan, and P. K. Foster, “Interpretation of the kaolinite-mullite reaction sequence from infrared absorption spectra,” J. Am. Ceram. Soc., vol. 57, pp. 57-61, 1974.
[16] I. W. M. Brown, K. J. D. Mackenzie, M. E. Bowen, and R. H. Meinhold, “Outstanding problems in the kaolinite-mullite reaction sequence investigated by 29Si and 27Al solid state nuclear magnetic resonance: Ⅱ. High-temperature transformations of metakaolinite” J. Am. Ceram. Soc., vol. 68, pp, 298-301, 1985.
[17] K. Okada, N. Otsuka, and J. Ossaka, “Characterization of the spinel phase formed in the kaolin-mullite thermal sequence,” J. Am. Ceram. Soc., vol. 69, pp. 251-253, 1986.
[18] K. Okada and N. Otsuka, “Characterization of the spinel phase from SiO2-Al2O3 xerogels and the formation process of mullite,” J. Am. Ceram. Soc., vol. 69, pp. 652-656, 1986.
[19] R. E. Grim, Clay Mineralogy, Second Edition, pp. 57-70.
[20] C. Klein and C. S. Hurlbut, Manual of Mineralogy (after J. D. Dana), 21st Edition, John Wiley＆Sons, pp. 502.
[21] K. C. Liu, G. Thomas, A. Caballero, L. S. Moya and S. de Aza, in Ceramics Today—Tomorrow’s Ceramics (edited by P. Vincenzini), pp. 177-186, 1991.
[22] E. M. Levin, C. R. Robbins, and H. F. McMurdie, Phase Diagrams for Ceramists (edited by Am. Ceram. Soc.), Fig. 407, 1964.
[23] K. C. Liu, G. Thomas, A. Caballero, J. S. Moya and S. de Aza, “Mullite Formation in Kaolinite-α-Alumina” Acta metall. Mater., vol. 42, no. 2, pp. 489-495, 1994.
[24] Y. Hirata, Y. Matsushita, and H. Katsuki, “Colloidal processing and mechanical properties,” J. Am. Ceram. Soc., vol. 74, pp. 2438-2442, 1991.
[25] P. Boch, T. Chartier, and P. D. D. Rodrigo, High purity ceramics by reaction sintering in Ceramic Transactions 6: Mullite and Mullite Matrix Composites, American Ceramic Society., pp. 353-374, 1990.
[26] F. M. Wahl, R. E. Grim, and R. B. Graf, “Phase transformations in silica-alumina mixtrues as examined by continuous X-ray diffraction,” Am. Mineral., vol. 46, pp. 1064-1076, 1961.
[27] M. Schumucker, W. Albers, and H. Schneider, “Mullite formation by reaction sintering of quartz and α-Al2O3－ATEM study,” Journal of the European Ceramic Society., vol. 14, pp. 511-515, 1994.
[28] S. M. Johnson, and J. A. Pask, “Role of impurities on formation of mullite from kaolinite and Al2O3-SiO2 mixtures,” J. Am. Ceram. Soc., vol. 61, pp. 838-842, 1982.
[29] S. H. Risbud, and J. A. Pask, “Mullite crystallization from SiO2-Al2O3 melts,” J. Am. Ceram. Soc., vol. 61, pp. 63-67, 1978.
[30] W. D. Kingery, H. K. Bowen, and D. R. Uhlmann, Introduction to Cermaics, 2nd Edition, John Wiley, 1976
[31] B. Jirhennsons, M. E. Straumanis, “Colloid Chemistry,” McMillan Co., 1962.
[32] “Sol-Gel technologies and their products,” http://www.chemat.com/, CHEMAT Technology, Inc.
[33] 陳慧英， “溶膠凝膠法在薄膜製備上之應用”，化工技術，第80期，11月，1990.
[34] J. A. Pask, X. W. Zhang, and A. P. Tomsia, “Effect of Sol-Gel Mixing on Mullite Microstructure and Phase Equilibria in the α-Al2O3-SiO2 System,” J. Am. Cream. Soc., vol. 70, no. 10, pp. 704-707, 1987.
[35] J. A. Pask, and A. P. Tomsia, “Formation of Mullite from Sol-Gel Mixtures and Kaolinite,” J. Am. Cream. Soc, vol. 74, no. 10, pp. 2367-2373, 1991.
[36] H. L. Wen, and F. S. Yen, “Growth Characteristics of Boehmite-Derived Ultrafine theta and alpha-Alumina Particles during Phase Transformation” J. Cryst Growth., vol. 208, pp. 696-708, 2000.
[37] J. L. McArdle, and G. L. Messing, “Transformation, Microstructure Decelopment, and Densification in α–Fe2O3 Seeded Boehmite-Derived Alumina,” J. Am. Ceram. Soc., vol. 76, no. 1, pp. 214-222, 1993.
[38] M. Kumagai, and G. L. Messing, “Controlled Transformation of Boehmite Sol-Gel by α-Al2O3 Seeding,” J. Am. Ceram. Soc., vol. 68, no. 9, pp. 500-505, 1985.
[39] R. Roy, A. M. Kazakos, and S. Komarneni, “Sol-Gel Processing of Cordierite: Effect of Seeding and Optimization of Heat Treatment,” J. Mater. Res., vol. 5, no. 5, 1990.
[40] U. Selvaraj, S. Komarneni, and R. Roy, “Seeding Effect on Crystallization of Corfierite Glass Powder,” Journal of Materials Secience., vol. 26, pp. 3689-3692, 1991.
[41] S. Zhao, X. X. Huang, and J. K. Guo, “The Effect of Mullite Seeding on Reaction-Sintered Mullite-Zirconia Multiphase Ceramic,” Journal of Materials Science Letters., vol. 19, pp. 707-710, 2000.
[42] J. She, P. Mechnich, M. Schmucher, and H. Schneider, “Reaction-Bonding Behavior of Mullite Ceramics with Y2O3 Addition,” Journal of the European Ceramic Society., vol. 22, pp. 323-328, 2002.