Jurnal f the Krean Ceramic Sciety Vl. 45, N. 5, pp. 303~308, 2008. Synthesis f Mullite Pwders by the Geplymer Technique Se Gu Sn, Ji Hyen Lee, Jeng Mi Lee, and Yung D Kim GEOWHA E.S.R Research Center, Chunchen 200-944, Krea (Received May 15, 2008; Accepted May 21, 2008) Geplymer Technique w Mullite w Á xá Á½ y» (2008 5 15 ; 2008 5 21 ) ABSTRACT Mullite precursrs were synthesized with aluminsilicate gels frm mixture f aluminum nitrate and sdium rthsilicate by the geplymer technique at ambient temperature. Then, the gel was heat-treated in air up t 1200 C at intervals f 100 C. Raw and heattreated gels were characterized by TG-DTA, XRD, FTIR, 29 Si MAS-NMR, TEM. The result t examine the crystallizatin f behavir thugh DTA, the synthesized precursrs were crystallized in the temperature range frm 950 C t 1050 C. The XRD results shwed that the gel cmpsitins were begun t crystallize at varius temperature. Als, it was fund that the precursrs f M-4 begun t crystallize at abut 950 C. The M-4 XRD peaks were characterized better than M-1~M-3 at 1000 C. The frmatin temperature f mullite in this study is much lwer than that f previus sl-gel methds, which crystallized at up f 1200 C. TEM investigatins revealed that the sample with 10 nm particle size was btained via heat-treated at 1000 C fr M-4. Key wrds : Mullite, Aluminsilicate gel, Geplymer technique, Crystallizatin behavir, Nan size 1. Mullite w, š» w» ƒ š Al 2 O 3 -SiO 2 š w w w ƒ š. 1)» mullite w, 2) œe, 3-5) -, 5-8) š 9), - w w yw ƒ ywš š ƒ ƒ wš,» w yw w e w ƒ ³ w w š. w 1200 ~ 1300 C y w, g w». Geplymer 3 silic-aluminate inrganic plymer 1978 Davidvits w. 10,11) Crrespnding authr : Se Gu Sn E-mail : sgsn@hanmail.net Tel : +82-33-264-0980 Fax : +82-33-264-0970 z, geplymer w w wš.» geplymer 80 C KOH e» metakalin silica w w. geplymer w» w geplymerizatin ù w. 12,13) geplymer»» y ƒ w, w w š y w. w slgel w, û ù l j» silicate w w. 14,15) SiO 2 šƒ g w sl-gel, geplymer technique SiO 2 sdium silicate ù ptassium silicate w. Geplymer technique w mullite w ƒ w precursr w wš û yƒ ƒ w»» sl-gel w w. ƒ silicate aluminum nitrate w aluminsilicate gel w w š w mullite w. 303
304 Á xá Á½ Table 1. Experimental Cnditins n the Preparatin f Precursrs Sample Start Materials Si-surce Al-surce [Si 4+ ] ph [Al 3+ ] Injectin methd Si/Al Reactin temp.( C) Stirring M-1 M-2 Sdium silicate slutin 12.7 M-3 Sdium silicate slutin + 13.5 Sdium hydrxide M-4 Sdium rthsilicate >14 Aluminium nitrate [Si] [Al] [Al] [Si] 0.5 25 Magnetic stirrer Table 2. Identified Crystalline Phase as a Functin f Heating Temperature Heating temperature( C) N. 900 950 1000 1050 1100 1200 M-1 C C C C C C M-2 Am Am Am Am M M M-3 Am Am M M M M M-4 Am M M M M M C: Cristbalite, Am : Amrphus, M: Mullite 2. x Si œ sdium rthsilicate(2na 2 OSiO 2 1.1H 2 O, Wak) sdium silicate slutin w mullite w mw. Al œ aluminium nitrate(al(no 3 ) 3 9H 2 O, p, Wak) w. x Table 1 ùkü. p Si œ mullite w ph ywš w ww. Si œ ph 12.7, 3.5, >14 w w, ph 12.7 sdium silicate slutin w w, ph 13.5 sdium silicate slutin sdium hydrxide ƒw w. ph >14 sdium rthsilicate w w. Al Si Si Al w. x aluminsilicate gel, e z» 50 C 24 g. gel TGA/DTA(STD 2960, DSC 2910) w 1300 C¾ w w. mw ƒƒ 900 C, 950 C, 1000 C, 1050 C, 1100 C, 1200 C w y w. w XRD z» (PHILIPS, XPERT-PRO) w y w, mullite y w y 29 Si MAS- NMR(Unity INOVA600, Varian) w w. 3. š Geplymer technique w w mullite y y w» w TGA/DTA w, 5 C/min 1300 C¾ w. Fig. 1 ùk ü. Fig. 1 DTA v 100~ 200 C vjƒ ùkû ƒ š, M-4 950 C~1050 C vj y w ƒ. w TGA v DTA š ƒ 100 C~ 200 C w, 600 C ƒ. DTA š 100 C~200 C vj mullite t k w ƒ, 950 C~ 1050 C w vj w mullite» w q. ƒ 20~30%, M-4ƒ 30% ƒ j ùkþ. Si œ 900 C ~1200 C 5 C/minw w XRD Table 2 Fig. 2 ùkü. Si œ ƒ y w. p Al œ Si œ w M-1 x 900 C~1200 C cristbalite y. ù Si œ Al œ w, e»w w wz
Geplymer Technique w Mullite w 305 Fig. 1. Typical TGA/DTA curves f mullite precursr gels; (a) M-1, (b) M-2, (c) M-3, and (d) M-4. w M-2 ~ M-4 x» mullite ƒ. Mullite y ph ùkü. M-2 1100 C, M-3 1000 C l mullite š, w 1200 C¾ w mullite. w ph > 14 M-4 x w y 950 C JCPDS e (00-015-0776) w y w. w ƒ geplymerisatin š ƒ. Geplymerisatin š e w w. p 16) geplymer matrix SiO 2 Al 2 O 3 Si Al w š e». ph SiO 2 š yw ³ w mullite ƒ» û mullite ƒ ù ƒ. K. Ikeda û ph w gel w silica alumina yw w w» w, phƒ w gel v ù ke alkali activatin w gel w w aluminsilicate š šwš. y xk 15) Si Al w w ƒ ƒ w w spinel wš mullite e w ù, z š aluminsilicate gel w ƒ spinel 2 e š mullite y» û yƒ ƒ w ƒ. w geplymer technique w w mullite y» w 150 ~ 250 C û. 9,17,18) Fig. 3 w w mullite w w 29 Si MAS- NMR w. š Si-NMR š k 29 45«5y(2008)
306 Á xá Á½ Fig. 2. X-ray diffractin results f heat-treated samples prepared in varius reactin cnditins; (a) M-1, (b) M-2, (c) M-3, and (d) M-4. w w. Q0( 66~ 73 ppm) islated tetrahedra, Q1( 74 ~ 78 ppm) chain end Fig. 3. 29 Si MAS-NMR spectra f the precursr gels(raw) and calcined at 1000 C. trup tetrahedra, Q2( 83 ~ 88 ppm) middle grups, Q3( 95 ~ 103 ppm) branching sites, Q4( 103~115 ppm) crss-linking sites ùkü. 29 Si MAS-NMR M-2 M-4 as-prepared (M-2 Raw, M-4 Raw) 1000 C(M-2 1000, M-4 1000) w w ww ww. Fig. 3 M-2, M-2 asprepared M-2 1000 w, Fig. 2. M-2 1000 C pattern ƒ mullite ùkü qp y. w M- 2 as-prepared 1000 C r 29 Si MAS- NMR qp y 99.3 ppm vjƒ 110 ppm vj eƒ w ƒ. M-4 29 Si MAS-NMR qp XRD pattern y ew y w ƒ. M-4 as-prepared M-2 78.2 ppm 97.1 ppm vjƒ. M-4 1000 M-4 asprepared 78.2 ppm 97.1 ppm vj û. w 29 Si MAS-NMR qp 86.8 ppm, 90.0 w wz
Geplymer Technique에 의한 Mullite 분말의 합성 307 Fig. 4. The electrn diffractin pattern(a) and the bright-field image(b) f the heat-treated aluminsilicate gel at 1000C. ppm, 94.0 ppm, 109.2 ppm에서 확인되었다. 여기에서 앞의 86.8 ppm, 90.0 ppm, 94.0 ppm이 세 피크는 mullite의 전형적인 피크이며, 109. ppm은 Q4(1Al)를 나타내는 aluminsilicate 상의 Si MAS-NMR 피크이다. M-4 as-prepared의 78.6 ppm와 99.3 ppm피크는 모두 mullite와 aluminsilicate 상으로 전이되었음을 알 수 있었 다. Fig. 4.는 합성된 mullite 전구체(M-4)를 1000 C로 열처 리한 시료의 TEM 사진을 나타낸 것이다. 사진에서와 같 이 결정성 mullite 입자의 크기는 약 10 nm의 크기를 갖 는 것을 확인할 수가 있으며, 결정입자가 구형임을 알 수 가 있었다. 또한 전자회절패턴(a)의 이미지는 1000 C에서 열처리된 시료가 120면의 결정성의 mullite임을 나타내고 있다. 17) 29 4. 결 론 Geplymer technique에 의한 합성과 저온형 mullite의 합성이 상온에서 mullite 전구체 가능하였다. DTA를 통한 전구체의 결정성 거동 조사에서, 합성된 전구체는 950 C 에서 1050 C의 온도범위에서 결정화되었다. XRD 분석결 과 전구체는 다양한 온도에서 결정화 되는 것을 확인할 수 있었으며, 특히 M-4의 경우에는 950 C부터 mullite 결 정화가 진행됨을 알 수가 있었다. 또한 1000 C에서의 M-4 의 결정성은 M-1~M-3보다 우수한 것을 알 수가 있었다. 이러한 결과는 기존의 sl-gel 법 등에 의해서 합성된 gel 의 결정화 온도보다 150~250 C정도 낮은 결과이었다. TEM 분석을 통하여 1000 C에서 열처리된 M-4의 mullite 입자는 결정성의 10 nm의 크기임을 확인하였다. Acknwledgment 본 연구는 에너지관리공단 에너지자원기술개발사업 (N.2006-R-RU11-P-23-0-000-2006)지원으로 며, 이에 감사드립니다. 수행되었으 REFERENCES 1. H. Schneider, J. Schreuer, and B. Hildmann, Structure and Prperties f Mullite-A Review, J. Eur. Ceram. Sc., 28 329-44 (2008). 2. O. Byrgis-Mntes, R, Mren, Maria T. Clmer, and J. C. Farinas, Synthesis f Mullite Pwders Thrugh a Suspensin Cmbustin Prcess, J. Am. Ceram. Sc., 89 [2] 484-89 (2006). 3. G. P. Thim, C. A. Bertran, V. E. Barlette, M. I. F. Maced, and M. A. S. Oliverira, Experimental and Mnte Carl Simulatin: the Rle f Urea in Mullite Synthesis, J. Eur. Ceram. Sc., 21 759-63 (2001). 4. S. S. Sueyshi and C. A. Cntreras St, Fine Pure Mullite Pwder by Hmgeneus Precipitatin, J. Eur. Ceram. Sc., 18 1145-52 (1998). 5. S. Satshi, C. Cntreras, H. Juarez, A. Aguilera, and J. Serrat, Hmgeneus Precipitatin and Thermal Phase Transfrmatin f Mullite Ceramic Precursr, Int. J. Inrg. Mater., 3 625-32 (2001). 6. D. Amutharani and F. D. Gnanam, Lw Temperature Pressureless Sintering f Sl-gel Derived Mullite, Mater. Sci. Eng., A264 254-61 (1999). 7. G. M. Anilkumar, U. S. Hareesh, A. D. Damdaran, and K. G. K. Warrier, Effect f Seeds n the Frmatin f Sl-gel Mullite, Ceram. Intern., 23 537-43 (1997). 8. J. Parmentier and S. Vilmint, Influence f Transitin Metal Oxides n Sl-gel Mullite Crystallizatin, J. Ally. Cmpd., 264 136-41 (1998). 9. L. B. Kng, T. S. Zhang, Y. Z. Chen, J. Ma, F. Bey, and H. Huang, Micrstructural Cmpsite Mullite Derived frm Oxides Via a High-energy Ball Milling Prcess, Ceram. Intern., 30 1313-17 (2004). 10. J. Davidvits, Geplymers and Geplymeric Materials, J. Therm. Anal., 35 429-41 (1989). 11. J. Davidvits, Inrganic Plymeric New Materials, J. 제 45 권 제 5호(2008)
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