Inhibition Effect of Allylthiourea and 12Dodecanethiol on Copper Corrosion

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1 ACTA CHIMICA SINICA Vol No Ξ a b a a ( a ) ( b ) a Ξ NaCl 0 5 mol dm - 3 NaCl 98 6 % 98 5 % Inhibition Effect of Allylthiourea and 12Dodecanethiol on Copper Corrosion WANG Chun2Tao a CHEN Shen2Hao Ξ a b ZHAO Shi2Yong a LI De2Gang a ( a School of Chemistry and Chemical Engineering Shandong University Jinan ) ( b State Key Laboratory for Corrosion and Protection Shenyang ) Abstract Self2assembled monolayer of allylthiourea (AT) was first formed on copper surface 12Dodecanethiol (DT) was then self2assembled on the surface for subsequent modification Finally AC voltage was loaded on copper covered with the mixed film for further improvement After these processes an effective inhibition film was obtained as indicated by the high charge2transfer resistance shown in electrochemical impedance spectroscopy and low corrosion current density in polarization curves The maximum coverage and inhibition efficiency for copper corrosion was 9816 % and 9815 % respectively The mixed film was stable in a wide range of potential before and after AC voltage treatment Keywords self2assembly electrochemical impedance spectroscopy AC treatment inhibition efficiency : CH 2 CHCH 2 NHCSNH 2 N [1 5] Laibinis [1] S Aramaki [3] 0 5 mol dm - 3 Na 2 SO % SH [1 4] [5] : Aramaki [4] % Crooks [6] 91 2 % Ξ E2mail : edu cn Received August ; accepted October (No ) (No G )

2 152 Vol ; ( C) : mol dm - 3 NaCl 98 6 % 98 5 % ( ) ( Aldrich ) ( ) ( ) mol dm mol dm mol dm - 3 NaCl NaCl mm 99 9 % # 400 # 2000 ( SCE) mol dm - 3 NaCl Nyquist Figure 1 Nyquist impedance diagram for copper electrode measured in a 0 5 mol dm - 3 NaCl solution mol dm s mol dm min mol dm V 30 min ( 2a) ( 2b) 0 5 mol dm - 3 [14] NaCl 2 : 5 mv 1 60 khz 20 mhz 1 4 Zahner IM6 5 mv Hz 0 5 mol dm - 3 NaCl 30 min V 1 mvπs (20 2) [10] [11 ( R t ) ( C) 12] CuCl 2 - [11 13] measured ; fitted Figure 2 The Nyquist impedance diagrams of copper electrodes [7 9] with mixed self2assembled films measured in a 0 5 mol dm - 3 NaCl solutions mixed film measured ; mixed film fitted ; AC treated mixed Warburg ( R t ) mol dm - 3 NaCl Nyquist mixed film mearsured ; + AC treated mixed film fitted

3 No 2 : 153 Π CuCl mol dm - 3 NaCl Warburg 3 ( 4b) 3 3 R t R s W ( 4c) Π Warburg R a Tafel ( E corr ) ( CPE) P % CPE : P % = 100 (1 - iπi ) A cm % Figure 3 Equivalent circuits used for fitting impedance data in Figure 1 2 i i 7 56 A cm A cm % Z CPE = 1 ( j ) - n Y 0 Y 0 CPE n ( 0 n 1) [15] n = 1 CPE [16] 1 2 ( R t ) k cm k cm 2 R t 40 4 k cm mol dm - 3 [10] : (1 - ) = Rt ΠRt solutions (at a sweep rate of 1 mvπs) Rt Rt 93 3 % NaCl 98 6 % NaCl ( 1 mvπs) a ; b AC ; c AC Figure 4 Polarization curves for copper electrodes with and without mixed self2assembled films measured in 0 5 mol dm - 3 a Bare copper ; b before AC treatment ; c after AC treatment F cm - 2 Cu + Cl - CuCl + e - (1) 5 62 F cm - 2 CuCl + Cl - CuCl 2 - (2) 1 87 F cm - 2 NaCl [16 17]

4 154 Vol O 2 + 4e + 2H 2 O 4OH - (3) 4 [6] mol dm - 3 NaCl 0 1 V 6a V ( Π E corr ) 2 3 6b 6c 0 5 mol dm - 3 NaCl 5 mv V V 40 4 k cm % V Table 1 The charge transfer resistance and inhibition efficiency for copper electrodes covered with mixed film of AT and DT after AC treatment at various potentials Treating potentialπv R t Π(k cm 2 ) PΠ% a ; b AC ; c AC Figure 5 Dependence of C on the potential for copper electrodes covered with and without mixed film before and after AC voltage treatment in 0 5 mol dm - 3 NaCl solutions a Bare copper ; b before AC treatment ; c after AC treatment 3 : [18 19] 0 5 mol dm - 3 NaCl 91 2 % NaCl NaCl 98 5 % H 2 O [20 21] NaCl Cl - H 2 O [22] References [22] 1 Laibinis P E ; Whitesides G M J Am Chem Soc

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