HWAHAK KONGHAK Vol. 41, No. 1, February, 2003, pp. 51-57

���� ���� � � � CO2� ��� ���� �� ��

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(2001& 12� 26' (), 2002& 10� 22' *+)

Effects of Cosolvent on Supercritical CO2 Debinding in Metal Injection Molding Process

Yong-Ho Kim, Jong Sung Lim†, Youn-Woo Lee, Jong-Ku Park* and Chang Ha Lee**

Supercritical Fluid Research Lab., *Ceramic Processing Center, Korea Institute of Science & Technology, 39-1 Hawolgok-dong, Sungbuk-gu, Seoul 136-791, Korea

**Department of Chemical Engineering, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, Korea(Received 26 December 2001; accepted 22 October 2002)

� �

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' !# ()�*�� ()+,� -!. /� �' � 0� 12� 3! 4# . 5 67��� 89:;4)�

<�* = ��� CO2' !# >? �*�� � � >?�@� AB� CD� EF0G . �%� methanol,

1-butanol, n-hexane, dichloromethane� 40G . Paraffin wax HIJKL �M� NO 348.15 K, 25 MPa� PQ��

5 w% n-hexane� � 0R ST ��� CO2U� !0V >?W XY >?9� 2Z !� � 0GE, [�\ �

� ]� � � ^_ >?�@� `a bc�d T ef . g# >?9�' Fick� diffusion model� h�� �i# I\

jkl\ m nB0� o� pL0GE, !' !0V paraffin wax� pi�' 7W T ef .

Abstract − In this study, we have investigated the effect of cosolvents on supercritical CO2 debinding in metal injection

molding(MIM) process. We used methanol, 1-butanol, n-hexane, and dichloromethane as cosolvents. In paraffin wax based sys-

tem, the debinding rate was enhanced when non-polar or midium-polar cosolvents such as n-hexane or dichloromethane was

added into supercritical CO2, while it was decreased when polar cosolvents such as methanol or 1-butanol was added. For exam-

ple, the debinding rate was enhanced more than two times by adding 5wt% of n-hexane into supercritical CO2 under 348.2 K,

25 MPa in paraffin wax based system. It was also found that the debinding rate was much more enhanced with increasing con-

centration of n-hexane or dichloromethane in paraffin wax based system and increasing system pressure. The kinetics of debind-

ing were investigated using the Fick’s diffusion model and they showed good agreement with experimental data. By using this

model, the diffusivities of paraffin wax into supercritical solvent could be evaluated in each experimental conditions.

Key words: Supercritical Debinding, Cosolvents, Metal Injection Molding, Supercritical CO2

1. � �

��������(Metal Injection Molding(MIM)) ��(near-net

shaping)� �� ���� �� �� ��� � � 2��� �� �

� �� !" #$ %& ' ( )� * +,� -. )/. 01� MIM

23� ����� 4�56�� .�789:; ��< ( )=> �

���2 ?@�� A., ����BC DE� F�GHI JKL M�

N DE�O PDQR S2 �TUV K� �R� WXK/. �1Y �

R� Z[(debinding) �R�� Y/. Z[�R ��\C ���� ]

7BC DE�O �TK� �R!"^ MIM�R23 PX_� GB `

�+ * �`� �[Ka N/. �Y �b�c" 15-50%C binderO �

TUV K� �R�I de2 ��\2 f Dg� h!i ( )� �

R��. �' ( )/. j�3 ��\C k��� Dg�� DE�O

lm �=" �T' ( )� In� o� pq_r[. )!s �1Y

�?" MIMQ tuN vw� xeC y #�� DE�O �TK

� In2 z,� {. )/[1, 2].

I|C Z[�R!"� DE�O }L3 �TK� ~Z[�(solvent

extraction)�� ��U2 CU �TK� ��Z[�(thermal debinding)

� � _r �/. 01� ~Z[�[3]C �� � _� ~C ?U†To whom correspondence should be addressed.E-mail: limjs@kist.re.kr

51

52 ��������������� �

�!" �KL � � ��_. )� R�., ��Z[�[4, 5] G

BQ 2�[� f� PX_I de2 ���� �23 e�,� -.

)/. �� �r l�a DE�O �TKI JU3 DE�� �~��

� )� I\��Q ��G� �TK� �~Z[�(catalytic debinding)[6]

� ��_�/. DE�� ���� )� 9&(ntric acid) � ��&

(oxalic acid)C I\O � KL DE�O �TKa _��, #���

Z[�=� Fe/Ni �� Fe/Co(4-5µm, ��g$ 60%)C �� � 4 mm/h

��, Al2O3(�2µm, ��g$ 56%)C �� � 0.75 mm/h, WC-12%Co

(2.2µm, ��g$ 50%)C �� � 0.6 mm/h R=�. ��_�/[7].

�> I|C ��2 �U lm �=" Z[O (�' ( )!� �~�

�!" NOx �5� %�_s �O �TUV K� �,� -. )/.

�� �r ?��� � , h¡� `¢!" Z[�RC £In" #

{_� ¤� z¥o ?\O � Y In[8-10]�. �� ?��� � 

23� � ¦KL f ��23 I|C ��§/ ���¥� ]¨G

©/. z¥o ?\� I\2 �ª« lm ¬&=O -!�3= ­\�

® ¯=" �KL �(Y U°� -� v±� )/. �Y �h�!

" |²K� ?\�I de2 Z[QRG ��+°(surface tension)�

�r ���� ]7��C ����!" l�a ³´KL DE�O �

T' ( )/. ¡ pq23� �� �SC pq[11]O µKL z¥o

CO2O � Y In� I|C ��Z[� §/ ~� ����s �¶�

2 )r3= I|C ��§/ Dg� �/� ¤� ¬�Y · )/.

¡ pq23� z¥o CO22 � ~O M�KL z¥o CO2C �9�

k¦GH�3 � ~� Z[�=�C toO .¸K¹/. � ~"�

methanol, 1-butanol, n-hexan, dichloromethane(DCM)� � K¹/. z

¥o CO2� �º�C �9� -. )r �º� 89� UGH��

»Q��I� K� º�C 89 ¼ U_[ ½¾ z¥o CO2C �

9� k¦G�AI JU � ~O M�K� ¿� f� �À[. )

/[12-16]. �1Y � ~O M�g!"^ UGH.7 K� 89Q ?

�Y U= Á��Â(δ)Ã� -=> z¥o CO2C �9� k¦Gi (

)!s Z[�R2 � Gi �� DE�C ÄÅ� Æ�� �ÇK/.

' ( )/.

2. ��� ��

2-1. Solubility parameter theory-Hildebrand parameter

h��!" ~� 9BC U° { 89C U= Á��Â(δ)

" È�Y/. U= Á��Â� ̈ � y�2�[ k¦$(internal energy

change of vaporization)Q �b(molar volume)"3 q' ( ). �

1Y ÊË� Iz" KL Hildebrand � Scott /ÌQ ®� U= Á

�� ÊË2 �TY Hildebrand-Scatchard RÍ�Î(regular solution

theory)O �ÏK¹/[17].

(1)

(2)

LI3 ∆E12� ¨� y�2�[ k¦$, φ1, φ2� 89 1, 2C �b�

c, vm É�b, C.E.D� �Ð2�[(cohesive energy density)O �Y/.

h��!" ∆E12� Ñ�(> Ò � �� -a _Ó" δ1-δ2C Ã�

Ñ!� ¼ UN/. �' ( )/. 01� Hildebrand-Scatchard RÍ

­�Î º��� v( �ÔÑ � �� ��7o2 � KI JU �

ÏN Õ�r3 º� ­�� v( �ÔÑ � )� ��ÖEo2� �

� ×�ÇK¹/. �1Y e�,� UDKI JU Blanks� Prausnitz[18]

Hansen[19, 20], Chen[21]Ø ∆EO º�°(polar force), �&°(dispersion

force), (PDE°(hydrogen bonding force)!" �Ù3 UÚK¹. �1

Y ¬+N �ÐÁ��ÂO � KL Hidebrand �Î� ÊÄK¹/[22].

2-2. ����-Fick’s second law

~y23 ��\O µU �T_� DE�C ¬&=� �7C �@

�2 C|K� Û�s �7C �@� h��!" Ü=� ÝT�

~�7C ÞI� Ñ� d ß�à/. ?\y23 soluteC ¬&� hrá

d h��!" FickC �2�Í(Fick’s second law)� � Ks, Crank

[23]� Shewmon[24]� soluteC ¬&=Õ� /ÌQ ®� ?=K¹/.

(3)

LI3 C� GâyC soluteC ã=O �äy� ¤�., D� soluteC

¬&�=O �äå/. GâC {æO l�� K. Gâ ��23� ¬&

� hRKa hr�s Gâ ç23� ¬&� hr�[ ½�/. ' d

Õ (3)� UÚKI JY �oèé /ÌQ ®� �R' ( )/.

C=C023 0<x<l, t=0

C=0 h d x=l, x=0, t>0

SlabC ��, GB t� [� ê Gây2 ë¾)� soluteC Û� �ä

y� /ÌQ ®� �ì' ( )/.

(4)

h��!" GB2 j� Gây2 ë¾ )� soluteC Û� GâC J

í2 j� è�î /�Ó" R¬Y ã=O qKI� rï/. �1Y �

?" Èðã= �� ÊË� WXK., Èðã=" Õ (4)O �ìK�

/ÌQ ®/.

(5)

(6)

Õ (6) ñ0.8 C0C ��2 Õ (7)Q ®� ��Õ!" �ì' ( )/.

(7)

j�3 Õ (7)2 CU ¬&o( DO q' ( )/.

3.

3-1. ����

¡ pq2 � N ���� Èð]7ÞI� 1.31µm� �� z�

E� ÖE ��"3 ò5óQ ôõ ��" �ör÷ )!s, (A)#Y`

Ú23 q]K¹/. WC-Ni��� ����KI JU � _� DE�

� /ÌQ ®� � ��!" q�_r )/. DE�` #��� �[K

s ?@� �L� Aø�� ADE�, ����\2 Io� ù=O �

LK. Z[G2 ��\y2 ë¾ )r ����\� gÉ(slumping)_

� ¤� úI JY �DE�, ADE�C ?@�� §ûK. DE��

����BC ,ü�� ÊÄKL ������ F�Gi ø�!" M

�K� M��� 0¤�/. ¡ pq23� ADE�" paraffin wax�

microcrystalline wax { �[O � K¹. �DE�" low-density-

polyethylene(LDPE) 0ý. M��"� stearic acidO � K¹/. Table

1 ¡ ¿23 � N binder system� �äå ¤�/. ����Q D

E�C ÖE�� �b�" 50:50��!s, DE� ` Z[QR23 �

E12∆φ1φ2

----------- vm δ1 δ2–( )2=

δ C.E.D.( )1 2⁄ H∆ RT–vm

--------------------1 2⁄ E∆

vm

-------1 2⁄

= = =

∂C∂t------- D∂2C

∂x2---------=

c x t,( )4c0

π-------- 1

2n 1+--------------

n 0=

∞

∑ exp D 2n 1+( )2π2t–

l2------------------------------------

sin 2n 1+( )πxl

-------------------------=

c

c t( ) 1l--- c x t,( )dx

0

l

∫8c0

π2-------- 1

2n 1+( )2---------------------

n 0=

∞

∑ exp D 2n 1+( )2π2t–

l2------------------------------------

= =

cco---- 8

π2----- 1

2n 1+( )2---------------------

n 0=

∞

∑ exp D 2n 1+( )2π2t–

l2------------------------------------

=

c

cco---- 8

π2-----= exp Dπ2t–

l2---------------

���� �41� �1� 2003� 2�

���� ������ � ��� CO2� ��� ����� ��! "# 53

T_rV' ADE�� S\ DE�C 71.3 wt%O �[K¹/. ¡ Z

[¿2 � ' ����\O �èKI JKL �Ä ����Q DE

�O 50:50 �b�" ÖEI(JSB-250, R�Io)2 þ. 413.15 K23

2GB .�a ÖEK¹/. �ÿa ÖEN ÖE8� 413.15 K" ��_�

����I(ID25EN, LG)2 þ. �°� �KL ��K¹/. Fig. 1

����Y WC-Ni ²9C ����\O �äå �à!", ���

21mm {æ� 3 mm�s, Go�C h�" � N/. ¿2 � N CO2�

� ~� Table 22 �äy�/. � ~"� n-hexane, dichloromethane

(DCM), methanol, 1-butanol� � K¹/.

3-2. ��

Fig. 223 §� ·� ®�, ¡ ¿+í� Þa 3��!" �� ( )

/. � ��� � ��"3 ­�C CO2O Z[ cell" �K� .

���(NP-D-321, NS Pump Co., LTD, �#?$ 17.4 ml/min)� �

~O �K� .���(NP-S-321, NS Pump Co., LTD, �#?$

8.7 ml/min), 0ý. �_� �&¦ PO ¿Ü=" ��K�

electric pre-heater" q�_r )/. { ��� Z[�"3 Z[ cellC

ÞI� �" 10 cm, �" 11 cm, Ý� 18 cm�. y� $ 300 cc�s

SUS316!" �ÑK¹/. Z[ cell �. 120oC, 40 MPaª[ � � �

ÇKs, Gâ� �a þ. � ( )=> ���2 ]q(I.D.=5 cm)O �

��. Z[è ��Q ��2 ́ G�� �üKL Z[QR� �Ï!" t

¸' ( )=> K¹/. Z[ cellC �°�R2� pressure transducer

(SENSOTEC, TJE/0743-06TJA)� digital indicator(SENSOTEC, L20000WM1)

O � K¹!s dead weight gauge(NAGANO KEIKI PD 12)" §R

KL ���JO �0.005 MPa" ?[G©/. � ��� �ý�"3 Æ

�N ADE�� z¥o CO2C ÖE?\� back pressure regulator

(TESCOM, 26-1722-24)O µU G5�C �°� hRKa ?[_�3

�ýI" ��N/. ��N z¥o CO2� �ýI23 �°� �� �

�!" ��_r U°� �Ka _. �d Ú�N .�C DE�

� �ýI ·�2 ��a N/. �ýN ��C CO2I\� �ýI !

" ��_s, CO2� ��_� ��2� rotameter� �&?$oO !í

KL Z[QR2 � N CO2C Û� o&' ( )=> K¹/. ¿�

µKL DE�� �TN GâC "a� R¯�#(OHAUS, E04130)�

� KL �RK¹/.

3-3. ����

����IO � KL �ÑY Gâ� Z[ cell (Fig. 2(6))2 þ�/.

Z[èC ]qO ûS$ ¯%Y & �I'Üè� electric pre-heaterO

�K� Ü=" ()/. ¿ èé2 (� Ü=� ?[_� CO2 cylinder

C *+O �. .���O Ñ@G� Z[è y�O ��G,/. @G2

� ~ reservoir� pDN .���= Ñ@G�3 Z[è y�" �

~O A]G,/. A]_� � ~C Û reservoirC -�� §�3 è

Fig. 1. Metal injection molded part(watch-band).

Table 1. Characteristic of the binder systems

Composition(wt%) Density(g/cm3) Melting pont(K)

Binder Asystem

Paraffin wax Major binder 71.3 0.82-0.85 338.15-343.15LDPE Minor binder 23.2 0.90-0.94 371.15-388.15

Stearic acid Surfactant 5.5 0.84 340.15-342.15

Binder Bsystem

Microcrystalline wax Major binder 71.3 0.84-0.87 350.15-353.15LDPE Minor binder 23.2 0.90-0.94 371.15-388.15

Stearic acid Surfactant 5.5 0.84 340.15-342.15

Table 2. Source, purity and solubility parameter of the chemicals usedin this study

Chemical Source Purity(%)Solubility parameter(a)

(J1/2/cm3/2)[19]

n-Hexane MALLINCKRODT 99.8 17.24Dichloromethane MALLINCKRODT 99.9 19.93Methanol J. T. Baker 100 14.281-Butanol KANTO 99.0 11.30(a)at 298.15 K

Fig. 2. A schematic diagram of the experimental apparatus.1. CO2 cylinder 9. Air bath2. High pressure pump 10. Pressure transducer3. Cooling circulator 11. Rupture4. Pre-heater 12. Back-pressure regulator5. Cosolvent reservoir 13. Separator6. Extraction vessel 14. Rotameter7. Metal sample 15. Dry gas meter8. Thermocouple

HWAHAK KONGHAK Vol. 41, No. 1, February, 2003

54 ��������������� �

.Y/. CO2 /0C Û ��C strokeO è.KL (Æ. Z[+í

y� �° back pressure regulatorO � KL è.Y/. ¡ ¿23

� CO2C ?$� 1 l/min(at 1 atm)!" ?[K¹/. �K� Ü=� �

°� ?[_� Z[ cell y23� � ~� ÖEN z¥o CO22 CU

3 Z[� �ör[a _s, � ÖE?\� back pressure regulatorO

µKL hRY ?$!" ��N/. ��N ÖE?\� separator23 D

E�� CO2" �ý_., CO2� �&?$oO µQK�3 P�N CO2

Û� �&N ê !" ��N/. Z[N Û GC "ak¦2 CU

�RKs DE�C 70 wt%(ADE�C 98 wt%)� �T< dª[ ¿

� (�K¹/. Z[QR23� h��!" ADE� (paraffin wax) �

� �TK. �DE�� .�7 89(LDPE) �TK[ ½�/. �D

E�� ADE�� �TN & ����\C ��� ?[KIJU3 G

ây2 ë¾ )rV Y/. �� �DE�� �T_� Z[ ê PDQR

!" Gâ� �@G ��\2 Dg� %IT� �\� 1[� ì��

hr�/. �1Y .�7 89 PDQRC h��� ��U QR�

Tí�3 �TN/.

4. �� ��

4-1. Paraffin wax microcrystalline wax�� ���� ��

h��!" z¥o CO2� �º�� 2. )r º�§/� �º�

9� UGH�� 3 »Q���. 45÷ )/. ¡ pq23 � N

{ �[ wax̀ paraffin wax� �7qè� Ä�� ¦(P� AO �ö.

)r3 dispersion force� �7qè2 [��� 6� �[K. )/. j�3

�º� �9� ~� ùY 89��. �' ( )/. 01� microcrystalline

waxC ��� Ä�� ¦(P§/� isoparaffin �� naphthene� AO �

ö. ). DR� ~� Ñ. í¯K/. ' ( )/[25].

¡ ¿23� � ~" methanol, 1-butanol, n-hexane, DCM� �

K¹/. 7� paraffin wax� ADE�" � N Gâ� 348.15 K, 25

MPaC z¥o CO2" Z[K� QR23 5 wt%C methanol, 1-butanol,

n-hexane, DCM� 88 M�K¹� d 1GB@Ï �T_� DE�C "

a�c� Fig. 32 �äy�/. �23 9K¹:� paraffin waxC �

º� �9 de2 n-hexane�� DCMQ ®� �&°(dispersion force)

� [��� � ~" M�K¹� d Z[c� ~� F�_� ¤� ¬

�' ( )�/. ;, <( z¥o CO2O � KL Z[K� ¤§/ n-

hexaneQ DCM� M�K� paraffin waxO UGH5� z¥o ~

C U°� ¨�KL Z[GB� �=_[� methanol�� 1-butanol

� M�K¹� d� z¥o ~� º�C �9� -a _r paraffin

wax� ~2 ¼ U_[ ½¾ <( z¥o CO2�� � K¹� d

§/ �$5 Z[GB� ¨�Ka _� ¤�/. �Y h��!" %8

_� U= ÊËQ� /�a º�� ùY methanol� � ~" �

K¹� d§/ º�� �#�!" �Y 1-butanol� � ~" � >�

�� Z[ »c� 3? @r[� ¤!" �äA/. �1Y DQ� �

~� paraffin waxBC U= Ê˧/ paraffin waxO ���� ]7

2 ¼ ,ü_=> ��� Ê9GH� stearic acid� � ~BC U=

ÊË!" !B < ( )/. Fig. 4� �1Y �?O !BKI JU ��

�� ]7 �23 paraffin wax� Z[_� QR� B�Ka =զK

L �ìY 0C�/. 0C23 §:� z¥o CO2 ~y2 �&_r

)� methanol �7�� ������" �r� (Fig. 4(b)) paraffin wax�

����� DEGH. )� stearic acidO UG� (Fig. 4(c)) paraffin

waxO ���� ]7��23 ZüGH� (Fig. 4(d)) D'� Ka N/.

;, Z[�=O E�K� AN X� paraffin wax2 #Y FG��

~C U°�I de2 º� ~O M�K� ~C �9� º�� 2

a _Ó" ~� paraffin waxO FG�!" UK5� �9� �K

_r S\�� U=� @r[a N/. /�, { º� ~2 #U3�

!BK� º� ~-stearic acidBC DE°� ����-stearic acidC D

E°§/ ùKL ���� ]7� paraffin waxBC DE� Hr[��,

�d methanol-stearic acidC DE°� 1-butanol-stearic acid §/ ÞÓ

" Z[c� �#�!" Þa �ä�� ¤�/. Methanol�� 1-butanol

Q stearic acidBC DE°� U= ÊË23 �I' �� Table 223

§� ¤Q ®� methanol δ=14.28 J1/2/cm3/2[19]�. 1-butanol δ=

10.30 J1/2/cm3/2[19]�s, stearic acid� Hildelbrand-Scatchard RÍ ­

�Î(Õ (2))2 CT δ=18.20 J1/2/cm3/2� _��(�d stearic acidC ∆E

� Fedors[26]2 CU o&N Ã� � K¹/), { 89C solubility

parameterC ��� Ñ�(> U°� ÞÓ" stearic acid� 1-butanol

§/� methanol2 3 ¼ UN/� ¤� 4 ( )/. �1Y ì�

z¥o Æ�QR23 � ~� -. )� #��� D'� !BK� ¤

!"^ � ~ ÄR2 )r �1Y �ýO �UY/� »Q�� �

~O �a ÁJ' ( )� ¤�/. ;, z¥o CO2O � Y Z[¿

23 � ~O M�' d� Z[K.7 K� 89Q U= Á��Â

� ?�Y � ~O M�K� ¤� ~� »Q���. �' ( )/.

Fig. 5� 358.15 K, 25 MPaC z¥o CO2 èé23 microcrystalline

waxO ADE�" � Y GâC ����, microcrystalline wax� �Fig. 3. Effect of cosolvent on binder removal rate in sc-CO2 debinding

for 1 hr at 348.15 K, 25 MPa: Binder A system.

Fig. 4. A schematic diagram of binder removal procedure in metal porewith cosolvent. ; paraffin wax, ; stearic acid, �; methanol,�; CO2.

���� �41� �1� 2003� 2�

���� ������ � ��� CO2� ��� ����� ��! "# 55

23 9Y ·� ®� �7qè� Ä� ¦(P K �[� )� ¦

(PC qèO L{ MgK. ). DRqè� Ñ. í¯KL z¥o

CO22� ¼ U_[ ½� v±� )/[27]. 01� � ~O M�K�

è�î F�N DQO N� ( )�/. �� <(Y z¥o CO2§/�

º�C � ~O M�K� �7qè `23 Ä�� ¾O qèO 3 »

Q�!" UGHI de2 Z[c� ¨�K� ¤�., �º�C �

~O M�K� �7qè` Ä�� qèO 3 »Q�!" UGHI d

e2 <(Y z¥o CO2§/ Z[c� ¨�K� ¤�/. �1Y DQ

� Joseph Ø[28]2 CU ��N xe� µU3= ¬� ' ( )/. � xe

2 CK� z¥o CO22 � ~O M�KL pristane(C19H40), phytane

(C20H42)Q ®� �Ä� ¦(P89� Æ�' d <( z¥o CO2O

~" � K� ¤§/� carbondisulfide, methanol� 88 10% M�

K� ¤� Æ� (c� F�G,/. K¹/.

4-2. ��� ��� �� ���� ��

M�_� � ~C ã=2 j�3= U=� k¦KI de2 Z[

c� k¦Y/. P ( )/. Fig. 6(a)� binder A2 tY Gâ�

348.15 K, 25 MPaC èé23 DCMC ã=O k¦Gi d �ä�� Z

[cQ GBQC 0���., (b)� �C ��23 1GB@ÏC Z[c

�� �IY 0���/. Fig. 6C 0��23 4 ( ):� DCMC ã

=� ¨�'(> Z[c� ¨�K� ¤� ¬� ' ( )�/. ;, <(

Y z¥o CO2�!" Z[K� ��23� GâyC paraffin waxO L

{ �TK�� 2GB 30�� PX_�[�, ® èé23 5 wt%C

DCMO M�' ��� 2GB �2, 10 wt%C DCMO M�' ���

1GB 30� �2 LQ paraffin waxO �T' ( )�/. �Y ¿�

µKL N Z[c� FickC diffusion model2 � G� o&Y DQ

Fick’s second law� ~� ¼ híK� ¤� 4 ( )�/. Table 32�

Fick’s second lawO µKL o&Y ¬&=O � ~C ã=2 j� �

IKL �äy�/.

4-3. ���� !" #$� CO2�� ���� %&� �� ��

�� ��

�°k¦2 jm Z[GBC RF� è�KI JKL 10 wt%C DCM

� M�Y z¥o CO2Z[ ¿23 Ü=O 348.15 K" hRKa ?[

Ks �°� 20 MPa23 28 MPa" ¨�G� ¿� (�K¹/. Fig.

7(a)� S\�� GB2 tKL �äå 0���., (b)� 1GB@ÏC

Z[c�� �IY 0���/. � ~O M�K� z¥o CO2 Z[C

��= <( z¥o CO2�� � Y Z[[11]C ��� ST�[" �

°C ¨�2 j� ~C U°� ¨�KL Z[c� ¨�K� ¤�

4 ( )/. Fig. 7� §� 10 wt%C DCMO M�' �� ® èé2

3 �°� 20 MPah d� 1GB 30� UýV ¤� 28 MPa" �°�

¨�GH� Z[GB� 30� �=_r 1GB �2 GâyC paraffin

wax(DE�C 71.3 wt%)� L{ �T_� ¤� ¬� ' ( )�/. �

��2= Fick’s second lawO µKL ¬&=O o&K¹. ¿DQ�

~� ¼ híK� ¤� Fig. 7� µKL 4 ( )/. Table 4� �°k

¦2 j�3 o&N ¬&=O �IY ¤�/.

5. � �

¡ pq23� ���� �����R ` z¥o CO2O � Y Z[

��23 Z[GB� 3? �=GH.7 L1 �[ � ~O M�KL

Z[�=O �RK¹. � ~C ã=� Z[ �°C RF� .¸K¹

/. DQO RýU §� /ÌQ ®/.

Fig. 5. Effect of cosolvent on binder removal rate in sc-CO2 debindingfor 3 hrs at 358.15 K, 25 MPa: Binder B system.

Fig. 6. Effect of the concentration of cosolvent(DCM) on binder removalrate in sc-CO2 debinding at 348.15 K, 25 MPa: (a) for the totalexperimental time, __: calculated by eq.(6); (b) for 1hr debinding.

Table 3. Comparison of diffusivities calculated by the Fick’s law withconcentration of cosolvent

Temp.(K) Pressure(MPa) Concentration(wt%) Diffusivity(m2/sec)(b)

348.15 2510 5.015×10−10

5 3.492×10−10

0 2.735×10−10

(b)Diffusivity of the paraffin wax

HWAHAK KONGHAK Vol. 41, No. 1, February, 2003

56 ��������������� �

for

by

-

ate-

,”

c-

of

r-

ing

m-

P.,

ss

(1) ����N GâC DE�O z¥o CO2" �TK� ¿23 Ä

�C �7qèO -. )� paraffin waxO ADE�" � Y GâC

�� n-hexane�� DCM� ®� �&°� [��� � ~O M�K

� paraffin wax� W¦°� ¨�_r Z[GB� f� �=Gi ( )

�/. �O �r n-hexane� 5 wt% M�Y �� <(Y z¥o CO2 Z

[§/ Z[GB� 2� �� �=_�/. 01� º� ~� methanol

�� 1-butanol� M�K� �$5 Z[»c� �Pg� 4 ( )�/.

(2) Ä�Q �Ä�C �7qèO -. )� microcrystalline waxC �

�2� methanol, 1-butanol, n-hexane, DCMC � ~2 L{ »Q��

Z[c� �äyr <( z¥o CO2�� � K¹� d§/ Z[GB

� �=_�/.

(3) � ~O M�K� z¥o CO2 Z[ ¿23 � ~C ã=�

¨�'(> 0ý. Z[�°� ¨�'(> ~C U°� ¨�_r

Z[�=� F�_�/.

� �

¡ pq� 1999X= QYIn�  �[R pq�Z� [�!" (�

_�!s, �2 #U ��[\ô/.

����

c : concentration of solute [g]

: average concentration of remained solute [g]

D : diffusivity of solute [m2/sec]

∆E : internal energy change of vaporization [J/mol]

∆H : molar enthalpy [J/mol]

l : tickness of injection molded part [m]

P : pressure [MPa]

R : gas constant

T : temperature [K]

t : time [sec]

vm : molar volume [cm3/mole]

x : mole fraction

'()* +,

δ : solubility parameter [J1/2/cm3/2]

φ : volume fraction

-. ,

0 : initial value

1 : component 1

2 : component 2

����

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Fig. 7. Effect of pressure on binder removal rate in sc-CO2 debindingwith 10 wt% DCM at 348.15 K, 25 MPa: (a) for the total exper-imental time, __: calculated by eq.(6); (b) for 1 hr debinding.

Table 4. Comparison of diffusivities calculated by the Fick’s law withpressure at constant concentration of cosolvent

Temp.(K) Cosolvent Pressure(MPa) Diffusivity(m2/sec)(b)

348.1510 wt% DCM

28 6.492×10−10

25 5.015×10−10

20 4.349×10−10

none 25 2.735×10−10

(b)Diffusivity of the paraffin wax

���� �41� �1� 2003� 2�

���� ������ � ��� CO2� ��� ����� ��! "# 57

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