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1 Jurnal f the Krean Ceramic Sciety Vl. 44, N. 7, pp. 393~402, Dense Plycrystalline SiC Fiber Derived frm Aluminum-dped Plycarbsilane by One-Pt Synthesis Dng-Geun Shin, Eun-Bae Kng, Dh-Hyung Riu, Yunghee Kim,* Hng-Sik Park,** and Hyun-Ee Kim*** Nan Materials Team, KICET (Krea Institute f Ceramic Engineering and Technlgy), Seul , Krea *Ec Materials Team, KICET (Krea Institute f Ceramic Engineering and Technlgy), Seul , Krea **DACC C. Ltd, Gyengsannam-d , Krea ***Schl f Materials Science Engineering, Seul Natinal University, Seul, , Krea (Received July 11, 2007; Accepted July 18, 2007) One-Pt w œ Aluminium dping s e l e w y ky³ Áœ Á x Á½ *Á y **Á½x *** ( )» ù q * ( )» y q ** z j *** w œw ( ; ) ABSTRACT Plyalumincarbsilane was synthesized by direct reactin f plydimethylsilane with aluminum(iii)-acetylacetnate in the presence f zelite catalyst. A fractin f higher mlecular weight plycarbsilane was frmed due t the binding f aluminium acetylacetnate radicals with the plycarbsilane backbne. Small amunt f Si-O-Si bnd was bserved in the as-prepared plyalumincarbsilane as the result. Plyalumincarbsilane fiber was btained thrugh a melt spinning and was pyrlyzed and sintered int SiC fiber frm 1200 ~ 2000 C under a cntrlled atmsphere. The nucleatin and grwth f β-sic grains between C are accmpanied with nan pres frmatin and residual carbn generatin. Abve 1800 C, SiC fiber culd be sintered t give a fully crystallized β-sic with sme α-sic. Key wrds : Plyalumincarbsilane, SiC fiber, Sintering, Sintering additive 1. ky³ š yw w wœ,, w w w. ky³ œ w p wš»y ƒ û 2100 C 1, 4) e yƒ ƒ w Prchazka, k w e w ky³ šw ky³ e, 2), 3) k 4) w y, y 5-7) 8) ƒ w w ƒ š. Hnda ky³ ü š 9) Crrespnding authr : Dh-Hyung Riu dhriu15@kicet.re.kr Tel : Fax : y ƒ g e y w wr, y w w ky³ ƒ, w ƒ 2 š w, 1900 C 1% w p w š šw. y ù y ƒw x ƒ j û. ky³ 10) w ù, 5) p, 6,11) 7). wr, w j» w β α k sqx ¼ w ƒ x p w, ƒw 1700~1900 C w z w œ š. 12) ky³ w š, Chi AlN 13) Sc 2 O 3 ƒw (IGP) e w ky 393

2 394 Áœ Á xá½ Á y Á½x ³ w. ky³ w. s e vw y, 14-21) Ishikawa 15,16,18) vw s e w z š w 500 nm j» y Tyrann-SA w. Dw Crning pk ƒ w l Sylramic ky ³ w. s e 14,17) vw w s e yw ƒw ww Ube Industries p xy w. w» w s 18) p l s e y» s e (PSCS) w w z ww yw j œ š SiC w. 19,20) v s e (s e ) tw-step œ w» œ y w s p l s e w w kw. 21,24) s p s e yw vw ³ w ƒƒ ƒ wš p w ky³ w» w. 1200~2000 C š w y w. p, 1800 C w,» œ x w e y š w. 2. x s p (plydimethylsilane) Wurtz w w w.» 22) 10 l 6 v j 3 l m 530 g Na z 110 C¾ ƒ w 1.3 l p j 8 wwš 8 w. w óù z k Na wš k š m w NaCl ppm w w œ» w w w s p w ) s p Al-acac(Al(III)- acetylacetnate) p ƒƒ 5% 1 % ƒw š š» š 350 C 400 C 2 g (Fig. 1). Al-acac» Fig. 1. Schematic diagram f 2 step prcess fr plyalumincarbsilane synthesis. w ƒ w» vw ƒw. w œ s e y s p Al-acac w s e One-Pt reactin š w. 21,24) w y œ 350 C 10~20 w y s e w» ww w» w 400 C w 15 ww. w (plydispersity)ƒ j s š, š y p yw., œ w w z, 250 C œ» p 1 w s e wš 400 C» 5 ~15 ww š s e w. FT-IR(FT/IR-460 Plus, JASCO C., Japan), GPC (Waters 2414, Ireland) š 29 Si MAS NMR(Varian Unity Inva 200 MHz sectrmeter, USA) s e,, wp w. Melting Pint d e (BI9100, Bamstead/ Elecrthermal, UK) TGA(TGA/ SDTA 851 e, Mettler, USA) w s e w w. w s e»x» wš œ w (260 C)¾ w 3 w z w. w 0.5 m «w 15 cm z w. z 200 C» 1 yw. y wš w» ù y z w š 60 MPa. y w» ƒ w š w wz

3 One-Pt w œ Aluminium dping s e l e w y ky³ 395 Fig. 2. Sintering schedule fr the fabricatin f dense SiC fiber. œ w 1200 ~ 2000 C w w. f Fig C/min w 1600 C¾ Ar» w z 1600 C N 2 +5% H 2» 1 w z Ar» yw 1800 ~ 2000 C¾ š w. ƒ w FE-SEM(JSM-6700F, JEOL, Japan) mw w XRD(D/ MAX-2500/PC, Rigaku, Japan), TGA(TGA/SDTA 851 e, Mettler, USA) w š SiC p sƒw s e w Fig. 3 s e w s p Al-acac FT-IR rp y w. Fig. 3(a) s p r p. 736 cm cm 1 Si-CH 3 bending, cm Si-CH 3 stretching w vjƒ ùkû. Fig. 3(b) Al-acac rp 1 600~1600 cm fm vj w ùkû. Fig. 3(c) Fig. 3(d) w ƒƒ s e 25) s e rp cm Si-H stretching w vj cm Si-CH 3 stretching w vjƒ p ùkû. Fig. 3(c) w Fig. 3(d) Si-H stretching vj ƒ. w Fig. 1 3(d) s e 1300~1500 cm w vj Al-acac fm l vj ew y w, s p s e y Al-acac ƒ Si-H ey w Al-acacƒ w s e y q. Al-acac 3 fm w š, w wù fm k œ w d. 19) Fig. 4 s e (a) s e (b) w 29 Si-NMR š. chemical shiftƒ ppm ppm ƒƒ SiC 4 SiC 3 H w w vj., SiC 4 / SiC 3 H d w s e w. 25). Hasegawa s e 27) massive w q x w, SiC 4 ü ùkù w xk š, SiC 3 H t ù kù w xk., SiC 4 /SiC 3 H ƒ j j s e ù t SiC 3 H w ƒ yw ey SiC 3 H w ƒ. chemical shift ppm ùkù Si-Si vj w s Fig. 3. FT-IR spectra f (a) plydimethylsilane, (b) Al(III)- acetylacetnate, (c) plycarbsilane, and (d) plyalumincarbsilane. Fig Si MAS NMR spectrum f plyalumincarbsilane. 44«7y(2007)

4 396 Áœ Á xá½ Á y Á½x Fig. 5. GPC chrmatgrams f (a) plycarbsilane and (b) plyalumincarbsilane. p ƒ s e y ùkú, Fig. 5 e vjƒ ùkù 8.0 ppm Si- O-Si w vjƒ ùkù. y Si-Si w ü w w Si-O-Si w ë ùkù dw, w w Al-acac w w fm l œ š q. w s e s s e 25) w» w GPC ww Fig. 5 ùkü. GPC w j yw vj d s ùkü. Fig. 5(a) s e GPC š 20~27.5 vj, Fig. 5(b) ùkü s e GPC š vj s Fig. 5(a) j ƒ. s s e ù 20 y w vj j x w. š Al-acacƒ t sw SiC 3 H w ey w ƒ w w Fig. 4 NMR l. Al-acac s e w Fig. 6 ƒ xk., w s e x š» Al-acacƒ s e t Si-H w ey Al-acacƒ x s e ƒ w w š w. fm š w s e w. 28 ùkù vj THF» w w vj. Fig. 7(a) s e 1000 C¾ 10 C/min w y ùkü. s e w w š, 200 C s ƒ û 350 ~ 800 C¾ ƒ û. 800 C yƒ 1000 C 60% Fig. 6. Schematics f plyalumincarbsilane synthesis mechanism. w wz

5 One-Pt w œ Aluminium dping s e l e w y ky³ 397 Fig. 7. TG analysis f (a) plyalumincarbsilane, (b) Al(III)- acetylacetnate under N 2 atmsphere and (c) DTG curve f (a).. Fig. 7(c) DTG š w ƒƒ 200, 360, 460, 540 š 660 C y vjƒ ùk ù, ƒ ƒ s e wƒ û š. s e š w CH 4, H 2ƒ w ƒƒ 550, 650 C w. 25,26) w, û j C 2 H 6 sww yw (CH 3 ) 3 SiH, (CH 3 ) 2 SiH 2 wì w 26-29). 350 C y vj / š w w. wr, 200 C Fig. 7(b) ùkü Al-acacƒ w» w ew w ey v Alacac fm w/ ƒ s e w œ s e 200 C»y 1 y w. ƒƒ 1400, 1600, 1800 C š 2000 C w ky³ w. k z w 1600 C N 2 +5% H 2» 1 w sw w. 30) Fig. 8 ƒƒ 1400, 1800 š 2000 C w ky³ XRD d w C 35 β-sic p vjƒ ù kù (Fig. 8(a)), ù SiC ƒ x dw. Fig. 8(b) 1800 C 35, 60, 72 β-sic vjƒ j ùkû, 33 α-sic p vj. l 1800 C β-sic β-sic α-sic ƒ. w α-sic x Tyrann-SA ùkùš, Ca 31) Li 32) 1800 C Fig. 8. XRD patterns f SiC fiber sintered at (a) 1400 C, (b) 1800 C and (c) 2000 C. w SiAlC SiCO XRD vj w vw w vw α-sic x š šw. Fig. 8(c) 2000 C w XRD p v j ƒ w š vj s dw. SiO 2 k vj. Fig. 9 s e š w ky³ w x. Fig. 9(a) 1400 C q ñwš e w q ƒ š, Fig. 9(b) Fig. 9. Crss-sectin image f SiC fiber sintered at (a) 1400 C, (b) 1600 C, (c) 1800 C, and (b) 2000 C. 44«7y(2007)

6 398 Áœ Á xá½ Á y Á½x Fig. 9(c)»œ w. wr, Fig. 9(c) Fig. 9(b) w x, w w w»œ œ e š e y /» w. SiOC 2.0, SiC 3.0 š w 30%, Fig. 9(b) Fig. 9(c) w ew. Fig. 9(d) e wš ü»œ SiC q š. t ¼ w»œ s e w ü w»sƒ Fig. 10. Crss-sectin and surface images f SiC fibers sintered at 1400 (a,b), 1600 (c,d), 1800 (e,f), and 2000 C (f,g) : a,c,e,g are crss-sectins and b,d,f,h are surface images f the SiC fiber. y t ¼ w»œ x. Fig. 10 ƒƒ 1400 C, 1600 C, 1800 C š 2000 C q t w C (Fig. 10(a)) t (Fig. 10(b)) ñwš»œ. w x Fig. 8 XRD ù β- SiC ƒ ³ w x ƒ š C w ü Fig. 10(c)»œ š j» ù l w. w ù»œ j» β-sic j» 1400 ~ 1600 C β-sic wx, š SiOC w x, ù»œ ù β- SiC j» ³ w w z w w w ƒ. ƒ g 1800 Cƒ SiC»œ j» ƒ ù»œ x w ƒ C (Fig. 10(c)) w β- SiC ƒ f ƒw ù ù j w ù»œ. t e w ùkü C w 1800 C w»œ e w ùkü. w. w s e w œ β-sic wx, š w Ì ù»œ x y w ƒ C SiCO ƒ š Fig. 10(c) 1600 C» w ƒ ƒ y ƒ š w CO (g) wì ü w k CH 4 (g) xk w w w. w 33) 1600 C ü ky³ wì ù»œ û C œ w컜 m w e y w 2000 C (Fig. 10(g)) ü»œ e w. ky³ j» 100~500 nm 1µm w C w EDS 36 wt% C 63 wt% Si(C/Si =1.3) š 0.4~0.9 wt% ü d. w, Fig. w wz

7 One-Pt w œ Aluminium dping s e l e w y ky³ XRD ü SiC k ƒ w C w w / w w e y v ƒ. Fig. 11(a-d) ƒ ƒ 1800 C 1 (Fig. 11(a)) 1 (Fig. 4 (Fig. 11(b)) w 1850 C 11(c)) š 1900 C 1 (Fig. 11(d)) w q w C, 1 (Fig. 11(a)) ù l w ky³ w. w ƒ ((a) (c) (d)) ky³ wì 1900 C 2000 C., 1800 C 4 ¼ w ((a) (b)) ky³ j ù ù j l j w. w SiC ƒ j SiC e y» w. Ishikawa š 15,16,18) w Tyrann-SA 1500 ~ 1700 C CO ƒ ùš 1800 C e yƒ, ky³ ü š y ƒ g e y j y w e š w. ù (a) (c) 9) (d) p j x y ƒ yw y q. SiC y ù k ƒ ƒ w, ü 4) w k ƒ j l w y ƒ. Fig. 11(e-h) e yƒ t l š. (e) (g) (h) ü e y w j ù 1900 C j»ƒ 1µm ƒ w 2000 C j ƒ. (e) (f) 1800 C 4 ¼ w w ù w e y w. Fig C 1 w š Fig. 11. FE-SEM images f fracture surface f SiC fiber sintered at 1800 C, 1 h (a,e), 1800 C, 4 h (b,f), 1850 C, 1 h (c,g), and 1900 C, 1 h (d,h) : a,b,c,d are interir regins and b,d,f,h are surface regins. Fig. 12. HR-TEM image f SiC fiber sintered at 1800 C, 1 h: (a) tw β-sic nan-crystal flded, (b) stacking fault cmpsed f twins, and (c) amrphus layer f extra free carbn. 44«7y(2007)

8 400 Áœ Á xá½ Á y Á½x Fig. 13. Schematic mdel f nanpre and SiC nancrystal frmatin during the high temperature pyrlysis f plycarbsilane derived SiC fiber (a) Pyrlysis stage and (b) Sintering stage. w n x. 30 ~ 40 nm j» ky³ š. ky³ d w š. j» š w j l. k 1~2 nm xk w, w k y y w e q. Fig. 13 ky³ w š ü w»œx ùkü. š w (Fig. 13(a)) (Fig. 13(b)) ù ƒ w. Fig. 13(a) 1200 ~ 1600 C w C z SiCO» l ky³ w ù ƒ 1400 Cƒ w» k w f š CO (g) SiO (g) xk»y 1600 C ù»œ x wì œ. 23,34) 1600 C w»»y š ù l w ky³ ù»œ û, w t k ƒ w. x ù»œ ù j» s ³ z œ e y j w e. w wz

9 One-Pt w œ Aluminium dping s e l e w y ky³ 401»» eyw ü k w k Si/C stichimetry ƒ w. 30,33) Fig. 13(b) w SiC C ù SiC ù»œ ³ w š k 1800 C š yƒ ùš, e yƒ w C k w wš š ³ w SiC ù ù»œ š ³ w e y ƒ. w œ k ƒ (Al, B) w w ƒ ƒ v w. 4. p œ mw s p Al(III)- acetylacetnate j One-Pt reactin m w v s e w w š š w y SiC w. s p e y Al-acacƒ s e t w SiC 3 H ey ww s e x w s e Si- O-Si w C SiOC SiO (g), CO (g) w ü ù»œ ƒ ù k ƒ w ƒ 1800 C š œ mw e y. ky³ ù j l š w k ƒ e y» w q C œ mw e wš y SiC w ù ky³ 500 nm w 1µm w. y ky³ š ü y p j w š l w ƒ. w w œ w e w ³ w ù w ƒ v w. Acknwledgment» (GNT )» (GRT ). REFERENCES 1. S. Prchazka, The Rle f Brn and Carbn in the Sintering f Silicn Carbide, in Special Ceramics 6 British Ceram. Research Assciatin, (1975). 2. H. Suzuki and T. Hase, Brn Transprt and Change f Lattice Parameter during Sintering f β-sic, J. Am. Ceram. Sc., 63 [5-6] (1980). 3. W. Bcker, H. Landfermann, and H. Hausner, Sintering f α-sic with Additins f Aluminum, Pwder metall. Int., 10 [2] 87-9 (1978). 4. S. Prchazka and R. M. Scanlan, Effect f Brn and Carbn n Sintering f SiC, J. Am. Ceram. Sc., 58 [1-2] 72 (1975). 5. M. A. Mulla and V. D. Krastic, Pressureless Sintering f β- SiC with Al 2 O 3 Additins, J. Mater. Sci., (1994). 6. K. Negita, Effective Sintering Aids fr Silicn Carbide Ceramics Reactivities f Silicn Carbide with Varius Additves, J. Am. Ceram. Sc., 69 [13] C (1986). 7. D. Fster and D. P. Tmpsn, The Use f MgO as a Densificatin Aid fr α-sic, J. Eur. Ceram. Sc., (1999). 8. J. K. Lee, H. Tanaka, and H. Kim, Frmatin f Slidslutins between SiC and AlN during Liquid-phase Sintering, Mater. Lett., (1996). 9. S. Hnda, T. Nagan, K. Kanek, and H. Kdama, Cmpressive Defrmatin Behavir f Al-dped β-sic at Elevated Temperature, J. Eur. Ceram. Sc., (2002). 10. R. AUGAlliegr, L. BUGCffin, and J. RUGTinklepaugh, Pressure-Sintered Silicn Carbide, J. Am. Ceram. Sc., (1956). 11. A. K. Samanta, K. K. Dhargupta, and S. Ghatak, Decm- Psitin Reactins in the SiC-Al-Y-O System during Gas Pressure Sintering, Ceram, Int., (2001). 12. W. J. Mberlychan, J. J. Ca, and L. C. De Jnghe, The Rles f Amrphus Grain Bundaries and the β-α Transfrmatin in Tughening SiC, Acta. Mater., 46 [5] (1998). 13. H. J. Chi, Y. W. Kim, M. Mitm, T. Nishimura, J. H. Lee, and D. Y. Kim, Intergranular Glassy Phase Free SiC Ceramics Retains Strength at 1500 C, Scripta Mater., (2004). 14. A. R. Bunsell and M. H. Berger, Fine Diameter Ceramic Fibers, J. Eurp. Ceram. Sc., (1995). 15. T. Ishikawa, Y. Khtku, K. Kumagawa, T. Yamamura, and T. Nagasawa, High-Strength Alkali-Resistant Sintered SiC Fiber Stable t 2,200 C, Nature, (1998). 16. T. Ishikawa, Advances in Inrganic Fibers, Adv. Plym. Sci., (2005). 17. D. C. Deleeuw, J. Lipwitz, and P. P. Lu, Preparatin f Substantially Plycrystalline Silicn Carbide Fibers frm Plycarbsilane, US Patent N. 5,071,600 (1991). 44«7y(2007)

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