Carbn Letters Vl. 10, N. 3 September 2009 pp. 239-249 Nuclear Graphites (I) : Oxidatin Behavirs Wng-Ki Chi 1, Byung-J Kim 2, Se-Hwan Chi 3 and S-Jin Park 1, 1 Dept. f Chemistry, Inha Univ., 253, Nam-gu, Inchen 402-751, Krea 2 Jenju Institute f Mechinery and Carbn Cmpsites Palbkdng-2ga, 817, Jenju, Jellabukd 561-844, Krea 3 Dept. f Nuclear Hydrgen Prject, KAERI, Daejen 305-353, Krea e-mail: sjpark@inha.ac.kr (Received August 3, 2009; Accepted September 11, 2009) 1. lp s p ~v s p p qm p p. a, b p, c p van der Waals p p p sp. lp rp n kr l, r rq,, q, q l n pp, q n lp q l p l p p q ~ vv~l n p [1-4]. np 4 m d (very high temperature reactr, VHTR) p 900 C p l nrp qp lž}, p lr, p t q vp p lp e sq, q, ql pn p. lp t ql p pl t ql e p lv Ž} eq [5]. q l lp p q l p np l p p p p rl pp Ž}l p p p rl np kk q nml rp. lp p t q s l p l Ž}p er v l p nm p q p [6]. q l n lp t ql p ˆ v sv l sq l rp pp l p eˆ. q l n lp p r v npp m p l CO 2 pp p [2,7]. lp rp tl 450 C l pl. q 800 C p p ml l l v l l ~ ~p k p d n p, v nm t l p pp dl l p p p m r l pl p p pl p n tn. q q l p r p 40%l tp n ƒ q l n q lp n p n p p. l n,, lp p nˆ p IG-110p t n p. IG-110p n p 20 ppm p p p 1.77 g/cm 3 l l t,, l q lp n lv p. q lp t ql p l l pp l p rp l v k p. q lp l p q p kr ~ re tn pq q lp l q kr l n tn. 2. 2.1.1. q q l l p l m t qp lt v q q r, t q q v kkk k,, l l v v k p v plk. q n v, l, t, p p. lp q n q p n lp q p p sn tn pqp [8,9]. v p q p p p l rp l p q l p q r l pv k. l m n l n l l v, n [10]. lp l p p 2,000 C r v q m v p pv, l p p l l tp l n nl t p n. p rp l q n t r p pp l n q. 2.1.2. q q q p el t q p p t p, l pp v ep tl lv q p. t q lv,
240 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) 239-249 Table 1. IG (Ty Tans)m NBG (SGL) lp Fig. 1. m d n l. IG-110 IG-430 NBG-18 NBG-25 Density (g/cm 3 ) 1.77 1.82 1.853 1.82 Prsity (ttal) 21.33 19.11 17.64 19.11 Prsity (pen) 13.83 13.43 8.03 12.29-13.25 CTE 4.0 4.3 4.49 4.1 Grain size (µm) 20 10 1600 60 Thermal Cnductivity (W/mK) 113.9 129.6 131.7 123.8 Cke petrleum pitch pitch petrleum Resistivity (µω) 10.1 9.0 9.05 10.7 Weidmann-Franz Rati (R WF ) 3.858 3.912 3.998 4.443 Frming methd is-static is-static vibratin vibratin q p pn p rp r e l p t n l. ml p nr p q ql lq, l l l ˆ ˆ v p k 1mmp l pq, ql p n pp s q l rn l p q n s l p r p n sqp p re n erp. Fig. 1 Fig. 2 m d l rn l q p te lt p [13]. p Fig. 2. m d p te. r qp q l nl t,, v p p. p q ep n l n nl p ql n vl ˆ l p tn, el lv l t q p ql p l p p l m tn [11,12]. 2.1.3. m d (High Temperature Gas cled Reactr, HTGR) l d r q l qp m k 1000 C mp, lp m d l pn el r p r p, l pp p p q p. s q kr edšp eˆ p k k l v pn p qrp v p. p qr l m d p l mp p p n 1960 JAERI (Japan atmic energy research institute) p t l l p p lr m. l 2020 p r e p m l q lp p n. p p p n lp lp p p p lp p l l p dv k, lp l p p np p. v, lp p r p n lr ˆ p. lp s p p ˆ q lrs e k l rq p v l l p p. macr lp, micr p p p. Table 1p q l (IG-110, IG-430, NBG-18, NBG-25)p p rp p ˆ p Fig. 3p p lp rs lp rs p ˆ p [14]. 2.2.1. q lp q lp p (density), X r (XRD) 15, l (TGA), FT-IRp r m. q lp p Table 2l m p e l n 3 vp l p l p llp, IG-110p (apparent density) 3p 1.76 g/cm
Nuclear Graphites (I) : Oxidatin Behavirs 241 Table 3. q l (IG-11, IG-110, IG-430)p d (002) L c r Grade d (002) +Ë, L c +Ë, IG-11 3.355 274.8 IG-110 3.355 274.8 IG-430 3.354 272.9 Fig. 3. p lp rs lp rs. Table 2. q lp Grade IG-110 IG-11 IG-430 Bulk Density (g/cm 3 ) 1.76 1.77 1.81 Flexural Strength (MPa) 33.6 36.2 - Cmpressive Strength (MPa) 78.4 76.1 - C.T.E (350~450 C) 4.4 4.5 4.7 Electrical Resistivity (µ Ωcm) 998 1143 1312 Fig. 4. IG-110p XRD r [16]. r l. p e p rp 1.77 ± 0.02 l v k ltlp, p lp IG-110 p rs p vp cld is-stactic pressing (CIP) p r p IG-110 lp p p v p IG-110p v p n pp pl. Fig. 4 IG-110p l p Žk d (002) L c p Fig. 5. IG-110p FT-IR r [16]. l r XRD p. d (002) L c p k p Braggp e Sherrerp ep m. nλ =2d sinθ (1) L Kλ = -------------- βcsθ λp X p Žqp K pq 0.9 v 1.84p p β e (prfile)l spqp rp r p p. Ll p p lp n c p p ~ L c. p p Lrenz fittingp ee m p k m p ep p p fitting l p. y=y0+(2 A/PI) (w/(4 (x xc) 2 +w 2 )) (1) pl p XRD q l p IG-110p 2θ p 26.5 pp k plp r p p 0.362pp k p. p p p el p l d (002) L c p p Table 3l ˆ l. Table 3l p p p d (002) p 3.355 Ëpp k plp L c p 274.8 Ëp k pl. p rp ll p p ˆ l p l kr spp p pl. q l (IG-110)p s, v p p, q ˆ p r FT-IRp Fig. 5l ˆ l. p rp C=C pt p p pp p pp l pp l. q l (IG-110)p lkr p Ž p TGA r Fig. 6l ˆ l. q l n (2)
242 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) 239-249 Fig. 6. IG-110 q lp TGA r ; (a) N 2 atmsphere, (b) air atmsphere[16]. lp k q l p l } k q pp lr kr rp q p m m p 900 C p 1100 Cl r l 770 C q p 99.6% ltl p q p p p q p tl Ž l v k q p m r q 100% l t p Ž l v. p IG-110p p p r p lt p. tp 1100 C TGA e qpp 62.1% r l. l 70 C p 700Ë l qpp eq p 900 C qpp 91.2% Žk l. p rp n lp l p 900 C q p 10% p rp, 900 Cl p k 1% p ep IG-110 lp q ne kr l e rp p [16]. 2.2.2. q lp m d p e q n lp He q p p p l p e p pp p. q l p lp tn p p pp [17]. C(sild)+O 2 (gas)co 2 (1) C(sild)+H 2 O(gas)2CO (2) C(sild)+CO 2 (gas)2co (3) C(sild)+2H 2 (gas)ch 4 (4) m l lp 3 v [18]. m p nl ppˆ p ~ lp pp n }} pl. ~ l p p Œ lp v p pl. p mlp p (chemical regime) v ml p, ml pp n pl l ~ lp l p pp p l, lp p p p l p pl v k. p mlp v pml (mass transfer cntrlled regime)p. ml (In-pre diffusin cntrlled regime)l p v pp el pl, lp l p mlp pl v rp. p pml p m mlp p rp 600 C p l p ml, 600 Cl 900 C pl m l, 900 C p l v pmlp pp, p m p e p,, lp s l p k r p. ml l pp Fig. 7l ˆ l [19]. Fig. 8 9 q l (IG-11, IG-110, IG-430)p ml 1200 C v t ˆ l. m v l l p pl p. IG-11[20]p n e 500 C eq l IG-110 IG-430l r p m l eq l. IG-110 Fig. 7. m mll pp [19].
Nuclear Graphites (I) : Oxidatin Behavirs 원자로급 흑연 (IG-11, IG-110, IG-430)의 온도에 따른 무게감소 변화[19]. Fig. 10. Fig. 8. 원자로급 흑연 (IG-11, IG-110, IG-430)의 온도에 따른 산화량의 변화[19]. Fig. 9. IG-430의 경우 산화에 의한 무게감소 경향이 비슷하게 나타나 나 IG-430의 산화가 더디게 나타났다. 그리고 산화속도의 경 우 IG-11의 산화속도가 확연하게 빨랐고 IG-110과 IG-430의 산화속도는 상대적으로 느리게 나타났다. 그리고 3개 시험편 모두에서 500~600 C 부근에서는 산화가 느리게 진행되다가 700~900 C 부근에서 산화속도가 급격히 증가하고 1000 C 이 상에서는 일정한 산화속도를 나타내고 있다[19,20]. 이는 E. Lren Fuller, Lu Xiawei등 이 언급한 500~600 C 부근, 700~ 900 C 부근, 1000 C 이상의 3개 산화영역으로 각각 화학반응, 확산반응, 표면반응에 해당 한 것이다[2]. Fig. 10은 산화를 통해 0%, 6.15%, 10.50% 감량된 원자로 급 흑연 (IG-11)의 사진으로 육안으로 확인 하기에도 표면형 상의 차이가 있으며 산화가 진행되어 짐에 따라 흑연표면에 기공이 많이 관찰 되었으며, 6.15% 산화된 시편의 경우에는 국부적으로 커다란 기공들이 형성된 것이 관찰되었다. 이는 243 0%, 6.15%, 10.50%의 산화 된 흑연 (IG-11)[22]. 0%, 6.15%, 10.50%의 산화된 흑연의 SEM측정 결과 (IG-11)[22]. Fig. 11. SEM분석을 통해서도 확인할 수 있었다. SEM 분석 결과 산화 가 진행됨에 따라 흑연 표면에 기공이 발달이 관찰되었다. 관 찰배율을 200배로 관찰한 SEM 사진 (Fig. 11)을 보면 기공 주 위의 표면 산화 반응을 좀 더 용이하게 확인할 수 있다. 산화 전 표면 (0%)은 산화 후 (6.15% 및 10.50%)의 표면에 비하여 매끄러운 상태를 유지하고 있음을 확인할 수 있으며, 산화반 응이 진행되어짐에 따라 기공 주위의 평평한 표면의 요철이 증가함을 관찰할 수 있다. 이는 기공뿐 아니라 흑연을 구성하 는 조직 중 흑연화도가 높은 입자 (ckes)의 주위를 구성할 것 으로 예측되는 흑연화도가 낮은 영역 (disrdered binder)의 산 화가 빠르게 진행된다는 것을 의미한다. 따라서 관찰이 용이 한 커다랗게 발달된 기공 뿐 아니라 관찰되지 않은 매우 미세 한 기공이 잘 발달되었음을 추측할 수 있었다[22]. Table 4는 Archimedian methd (AM)로 측정한 기공율과 밀도 를 나타낸 결과이고, Fig. 12에서는 기공율과 밀도의 변화 관계를
244 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) 239-249 Table 4. Archimedian methdp p r wt. Lss s t p (%) (g) (g) (g) (%) (g/cm 3 ) 0 4.4703 2.2497 4.7325 10.56 1.80 6.15 4.2279 2.1573 4.6227 16.01 1.71 10.50 3.9372 2.0527 4.4055 19.90 1.67 (Emissivity)p r eˆ p. r p n q p l p l, ~p lr ˆ p l t pn [24]. Emissivity ppm p ~ l m pm p ~ l p p p rp. q v k v emissivity r p r, r l r p 3 v pp, r (radimetric emissivity methd)p e q~ l p m p ~ m r p [25,26] r (reflectivity measurement methd)p p p l e l p e e l p p, e p p emssivity p. l r (calrjmetric methd) e p e t e l p d Ž- v (Stefan-Bltzmann) p pn l r pp p. Emissivity ppp m l m, p m p ~ l mp p. m Tp ~ m l p l ~l p. m Tp ~ (black bdy) (emissin pwer) d Ž- v l p l p p tlv. E b =σt 4 (w/m 2 ) (1) Fig. 12. p p [21]. e m. v k q l (IG-11, 0% )p 3 1.80 g/cm r l p l ˆ r l. p p rm pv, e v rpv p rp n p Ž l v. pp v 3l 3 1.80 g/cm 1.67 g/cm mp, pp 10.56%l 19.90% v m [21]. 2.2.3. q lp Emissivity l lrp l vp pq p ll v rql v r l rp. l rqžp psp r vp l p rž, v qn l, p [23]. l r r ( ) r l σp d Ž- v (σ=5.6697 10 8 ), T p tlv ~p r m (K) E b ~p p. p rp ~ ~ p e(1)l p. r m Tp ~ E p. E=εE b = εσt 4 (2) l ε emissivity 0 1 pp p v er ppp ~p emissivity 1 q. Table 5 m l emissivityp ˆ p m v emissivity v p ˆ lp 5%m 10%e p emissivityp p v k k. m l emissivityp p Fig. 13l ˆ l p, m l emissivityp v p q ll p m. rm 500 Cl 0%l 10% v l emissivityp v pp IG-430 (23.6%), IG-110 (21.0%), PCEA (16.8%), NBG-18 (13.7%), IG-11 (12.2%) p ˆ p, p p p r p v p r p l emissivity v p Ž. 10% NBG-18p emissivity rm 100 Cl 0.89 p f re t q p p llrp, 0% NBG- 18p rm 400 Cl 0.538 f q p p ˆ l. 10% IG-430p emissivity rm 100~500 Cp r
Nuclear Graphites (I) : Oxidatin Behavirs 245 Table 5. q lp p, rm l emissivity wt. lss Temperature (%) ( C) 0% 5% 10% Emissivity IG-11 IG-110 PECA IG-430 NBG-18 100 0.721 0.681 0.731 0.682 0.737 200 0.599 0.601 0.663 0.626 0.627 300 0.611 0.585 0.645 0.657 0.609 400 0.626 0.582 0.587 0.646 0.538 500 0.650 0.558 0.596 0.647 0.649 100 0.819 0.786 0.861 0.815 0.847 200 0.760 0.776 0.797 0.805 0.777 300 0.755 0.771 0.795 0.816 0.729 400 0.746 0.759 0.681 0.818 0.681 500 0.693 0.666 0.691 0.755 0.738 100 0.839 0.835 0.866 0.854 0.890 200 0.762 0.783 0.850 0.812 0.834 300 0.760 0.775 0.803 0.819 0.756 400 0.756 0.764 0.718 0.824 0.694 500 0.729 0.675 0.696 0.800 0.738 Fig. 13. m l emissivityp ; (a) IG-11, (b) IG- 110, (c) PCEA, (d) IG-430, (e) NBG-18[27]. l ~ 0.8 p p p emissivity ˆ l [27]. Fig. 14. IG-110 lp 1150~1250 Cl s np. 2.2.4. q l er rn q l Fig. 14 m d l n q l (IG-11)p 1150~1250 Cl t q s np p er p. s l p p t q s p v l ƒv. p l v AGm WGp pp v kp, p s m l r k 850 C }l n qp s m [28]. lž} s p v l s p l kt s v. p p s m l s m p lž} p ˆ s p p p nl p ˆ. 20 C l s m vp lž} s l p Fig. 15l ˆ l [29]. lr pp m ps p s l p Fig. 16l ˆ l. (a) s r, (b) s p. q lp lr t p l p v p p r l p l r l ps. r p s p v m v, lr pp s p l s p v p v k. p p p p l vp k p. s m l v ˆ l r. p ˆ m s p v m p m yp n p ˆ. q lp ˆ p n l p rl qp v v s l p v. v pp s p l, s p v m q. s l v pp s m p [30]. n tp l d l m lp p v s creepl p p p m.
246 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) 239-249 Fig. 15. IG-110 lp 1150~1280 Cl s np lž }. Fig. 17. q lp s creep. p p m p r ˆ s creep v. Fig. 17p s q lp s creep p e p s m l p ˆ. q l p p p l CO 2 l v m r p ˆp r 4 q p m d (VHTR) ~ p. lp tn s n m d (VHTR)l lp lr, r, r p ( m t q s (neutrn irradiatin))l p l p q p lp l p lr, r, r Žk p q, nr kr p ~ pp [31,32]. l lp lr, r, r r p (He q, l) e t pl l r l n p r VHTRp e skr m l n t n r p v. kr p q m d p p r kl q p r n p l p q l e l rrp l p p. p rl m d p krp lp r l n tn. lp r e skr p p tn npp qn l lq p l lr, r, r, l q p r, r n l rr kr l n tn. 2.3. n Fig. 16. IG-110 lp s l p lr p ; (a) s r, (b) s. 2.3.1. np r v p l l kr
Nuclear Graphites (I) : Oxidatin Behavirs 247 r, p prp p m d p VHTRp qrp p, n s q ll q e p p [28]. q GIF VHTR ECp HTR-M, M1 l l l ~ r, l l s l l tl p. GENÏl m nr tp kr r l reactr vessl ll emissivity l q t n p r pp metal p reactr vessell emissivity l p. Oak Ridge l l reactr pressure vessell emissivity l pp, VHTRl rn q p vl l Winscnsin-Madisnl eq p. q n lp m crack kr l m Bath p McEnaney l p. pl v k n crack pl lr p p 3 v mlp. (1) an initial rise attributed t develpment f bridging in the crack wake zne. (2) a plateau regin where the prcess zne ahead f the crack bridging zne reach steady states, (3) a falling R curve r a rising and KR decrease prgressively and the plateau becme shrter. : ( ~11%) l R KRp p rvrp, pl plateaux w kr. 11%l l prcess zne sizep rvr v l plateaux v p p. ˆ EC, d, p p l l p n k p. -EC: r, kr, l p, qpn l l eq edš ( HTR) p 5 EURATOM Framewrk prgramme (HTR-M, HTR-M1)l EC5 l, m, s e l ( l l kr ) rp l 5 q lq l m, s e t (HFR-Petten,, s s : 25 dpa, 900 C p, m :1,800 ). - d : rp 2010 v Direct Cycle Mdular type m (HTR) l t rp l pp p 1,000 C p p GCR ( d )m r p kr p GCR s p GCRp, q rp r lpnp el Actinide t q Spectrump GCR p rp pl n lq p tl p. HTR kr m, pl p l rm pl lkr r q s (prsity, impurity, density) s (m, d flw rate) tr tl p. - p :p p 1960 TOYO TANSO C. q l (IG-110)p q l n k e l p l m. ˆp Oarail m d (HTGR) n l t q qrp m. 1997 HTGR m p ql t e l m l ( e ) tp m, s l p l m (Mdeling)l n q l 2004 JMTRp pn, m, s e mr (950 C p, He, s : 3 10 22 ncm 2, 10 dpa)p. 2003 l m ls e q rq mp, GIF VHTR EC p HTR-M M1 l l r rp l l ~r, l l q tl p. - :r 4 q (Gen-IV)p n q p 2017 p v pp, 2010 v n q m. pl n lq q UCARl H-451grade (GIF t l grade) r, q ORNLp tep 900 C p ms Fig. 18. q lp XPS r ; (a) NBG-17, (B) NBG-25.
248 Wng-Ki Chi et al. / Carbn Letters Vl. 10, N. 3 (2009) 239-249 Fig. 19. r q lp high reslutin O1S spectra; (a) NBG-17, (B) NBG-25. e p tl p (s :3.8 10 22 ncm 2, E>50 KeV). 2.3.2. p l 4 q p n m d p p q lp r p p l p,. q l l k q lp q l rp l p, pms lp, r s p, r t m lp p. v l q lp s p m l lp p p f, t lp r vr m p l tl p. Fig. 18p q lp r p XPS r l l lp l v 284.6 532.5 ev Fig. 20. q lp high reslutin O1S spectra; (a) NBG-17, (B) NBG-25. l C 1Sm O 1Sp plp, q lp n O 1S rp O 1S l v p p pl. Fig. 19 20p r p q lp high reslutin O 1S spectra rl C=O grup (Ketne, Lactne, and Carbnyl) OH grup (B.E. 528.3 ev) ˆ v l O-C-O peak (B. E. 531.7 ev) v p p pl [33-35].p Ž q lp l l p Ž l v. 4. qp t 1 l vp t vll q l p krrp p l n p kr
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