ÃÞ Al-Zn(7%)-Sn(0.1%)-Ga(0.015%) NaCl ι 2% CrO 3 +5% H 3 PO 4

Transcription

1 Ñ 32 ± Ñ 5 Vol.32 No Þ 10 Ø Journal of Chinese Society for Corrosion and Protection Oct Al-Zn-Sn-Ga ÒÃ É Ì À ÂÎ ĐÐÛ Ú Þ Ý ß ĐÜ ÊÔºØ Äº Õ Õ Ó : º SEM Al-Zn-Sn-Ga È Û Æ Ð «ÈØ ÅÐÜÛ ºÅ Ñ µ Ô Ø ph ºß Àà «Ü ¹ NaCl ÆÅ Ë Ï È Ð «ÅÈ Ø ph ¾ºß ßß ÔÍ Å Ü ºßÞ 0 10 cm àph Ð ÅÆ È Ga ½ ËË ¾ ÍÐ Ï ÅÉ Ð ±Ðµ Ľ È Ô ºß 10 5 cm ÃÂ Å Û È Â Æ : Ô Ë Ï ½ Ø Í : TG17.1 : A Ö : Ð Ñ»± ÎÇ Ó Ç Û Cl Ý ¼Ù»Ó Ý [1] Û Ï Â Á Î ³Ê Î ÞÌ ¹À ÂÓ ÊÊ» Ð Al-Zn-Sn-Ga Ç Ã Û Ä Û ¹ Ð Ó ¾ÐÞÞϵ ±Đ ³Ê Î ¹À ÊÅ È³Ê Î ÅÇ Ó [2 ] ÛÚÏà ¹ Ð Ó ph ¹Þ Ð Â Å È µ Ç Û NaCl ³Ê ÎÐ Ô Ç Ó ÒÊ Ý Al-Zn-Sn-Ga Ç Ó Ó ºÁÛ ³ 2 Ñ ¹ ZGJL0.01-C- ³ Î À̱ : ÁÊ : ËÕ½»Ù² Ü ( ) ËÕ ½µ» ( ) ÆËÕ»Ù Æ ß» (2010QN0022) ± Ù ÅÈ : µ «Ö«1987 ß¼«Ç¼«ßÏÉ Ñ Å Ù : µ « never-give-up-ljf@163.com «ÀÇ ³ÃÎÚűÚÅÓ ÃÞ Al-Zn(7%)-Sn(0.1%)-Ga(0.015%) Á  760 À φ20 mm 10 mm Ô ³ Þ Î ÍÝ φ15 mm 20 mm Ò Đ Å Î 3.5% NaCl ι 2% CrO 3 +5% H 3 PO Û 80 ÄÐ ¹ JSM-5610LV ³³ ¾ ι Å ¼Á¹ ½¹Þ EDS Ù Ã ¹ Ö³ Ó É ¹ NaNo Focus 3D ¼ÛüÁ ¹Þ 3 Ç Ô Ï Ô 1 Ý Ñ ¾Ð Ú¹ Ô 1a ¼ ¹ Ç Û ¾¾ ÃÏÁ Ð (Ô Ó ) Ð ¹ Í ²Ù Ô 1b 3.5% NaCl Î À µð ÁÅÆ ¾Ó (Ô Ó ) ¹ ÞÞ (Ô 1c Ó ) Ç Ì Ó ±É ĐØ Ð Ö Î Ä (Ô 1d Ó ) й Ð ½ EDS Å Ô 2 Ç Zn ÑÊ ÓÐ ÛÐ Sn ÑÊ Ò Ð

2 < 5h X % Fig.1 SEM morphologies of cast alloy after different soaking time in 3.5% NaCl solution: (a) 0 min, (b) 30 min, (c) 60 min and (d) 120 min Fig.3 Sketch map of pitting corrosion in anode alloy l _ % / )s~ 5(; 5 3 l A Al Zn Sn F\O R Fig.2 EDS analysis of second phase in cast sample A= 5/WI F?=& ( Al 0 ) y Zn Sn m R v F\O # d "?=& B\ ya#s /WI L 5s o ' b, V Y#l 53 z-m3s? ka)i Y# 52} z z a - =&}z zz 5/ =&}zoa zz l _ ( ; 53 \ + yk ` 53-z h 3s =&}z GJ -z6 e jæ [ : y 35 I Z ( ; _a3sv\g }O 356 Y * V af F?=& L V ^ 3s FV " 6& n > s\ 5 M\ 5n >dd IvW \ÆsK ( U,ea^ 3s Cl!3s k'%1, (;9V R 3s V\g <o5 + (1) w ) 5C 53 s"fo3 6 y 2 * ( ; < Qy \^ /l V % M } I e } 53s ph * (2) af 5 F F d WIs P (,X= kwvwm_a!o 53 \g> & J A=,X3s=&6&A= (3) - sl QCy ( W e & LaYj u D 9 < nvv r y 10 cm JIr () vw Al L V R Sn M Zn mr p 3 yo 35?Pp "hw 5C s 3+ [5] [7,8] [3] [6] 3+

3 5 : Al-Zn-Sn-Ga ÐÈ 09 Á Ä Ð ph Ð Å Û Ê Û»Ì Î [9] O 2 + 2H 2 O + e OH (1)» Î Al Al e (2) Ç Ð» ²» Á Ä Î Al 3+ + H 2 O Al(OH) 2+ + H + (3) Al(OH) 2+ + H 2 O Al(OH) H+ () ¼Å Ä Î Ý Al 3+ + H 2 O + OH Al(OH) H+ (5) ± Î (5) µ ²ÅÂ Û Î Å½Å D 1 D 5 ÐÞ Î Å c 1 c 5 Q = n F N I = dq dt = n F dn dt = n F D i dc i dx D i dc i dx = I n F (6) Å (5) Al O H Ò² à ¼ Æ Å dc 1 D 1 dx + D dc dx = I 3F (7) dc 2 D 2 dx + D dc 3 3 dx + 2D dc dx = 0 (8) dc 2 2D 2 dx + D dc 3 3 dx + 2D dc dx + D dc 5 5 dx = 0 (9) ( c 5 D 1 K 1 + D ) ( D 5c 5 D 3 c D ) = I x 3 F (10) n Ý Al Ò²  ÃÂÆF ÝÅ Ð ÂÆN ÝÓ ÂÆQ Ý Î ÁÆx Ý ÆI Ý Ë Þ ( Ç ¹ ¼ µ Ë Þ ÖÝÇ ³ Ë Þ A/cm 2 ÂÁ Ö) µ ²ÅÂ Ý [10 13] D 1 = D 2 = D = cm 2 /s; D 3 = cm 2 /s; D 5 = cm 2 /s Ý x=0 À¾ c 1 =0Æc 3 = mol/læ c =0Æc 5 = mol/læal 3+ H 2 O Ä Â K 1, K 2 Ý [7] K 1 = c c 2 5 c 1 = (mol/l) 2 = (mol/cm 3 ) 2 (11) K 2 = c 3 c 5 = (mol/l) 2 = (mol/cm 3 ) 2 (12) (7 9) Ó ÚÏ Ë Þ A/cm 2 ¾ ph ¹Þ Å Ô Ô¼Đ Ä» H + ÐÞÅ ½¹Þ Å Ë Þ ÝÁÛ H + ÐÞ ½¹ÞÞÏ ÞÌ ÞÞ Ó ¹ÞÛ 0 10 cm ÂÁÖ¾ ph Õ ÎÞ Å º ÞÌÓ Ü Ê Å¹Þ¼ ½Ç Ó Ù Ý¾¹ Ç Ð Û NaCl Ê ¹»ÏÁ µ [1,15] ¾ ½ÝÌ Î» ÏÁ OH ± ² ² µ OH ²ÅÇ Î Þ ¾ [16] Å Ç Ga ÑÊ Ó¹Ñ ÑÅ Ga ¼ Æ Ñ ÞÏÓ Ü Í ¹ (ÕÌ ) Ê ÞÌÌ Î ( ) [7] ± Ì ² ²Å ³ ² Ê ¾Ð ÕÂ Đ Ó ¹ À ³ÐÞÎ Õ ÝÈ» Ô 5 Î ³ Ô (Ô 1d ) ¹ÞÛ 10 5 cm ÂÁÖ ÚÏ Á Æ ÚÏÌÁ ÃÇ Ó ph value of corrosion pit Depth of corrosion pit/ cm Fig. Relationship between corrosion pit depth and ph value

4 10 32± Fig.5 3D morphology (a) and depth measurement (b) of corrosion pitting Đ ³Ê Î ÒÊ 5 ÇÏ (1) Al-Zn-Sn-Ga Ç ¹ ÏÁÐ Û Ó ±» µ (2) Ó ph ½¹ÞÞÏ Þ ÌÞÞ (3) Ó ¹ÞÛ 0 10 cm ÂÁÖ¾ ph ŹÞÆÜ Ó Ý¾¹ () Ç Ga Ñʽ Ó Ì Î ÞÏ Ì Î Þ Ó Đ Ó ³ÐÞλ Ë [1] Salinas D R, Garcia S G, Bessone J B. Influence of alloying elements and microstructure on aluminum sacrificial anode performance: case of Al-Zn [J]. J. Appl. Electrochem., 1999, 29(9): [2] Yang T J, Li G M, Chen S, et al. Self-catalysis action in pitting propagation process of low alloy steels[j]. Corros. Prot., 2010, 31(7): ( ³,,. É ²Õ µì [J]., 2010, 31(7): 50-51) [3] Kang J, Fu R D, Luan G H, et al. In-situ investigation on the pitting corrosion behavior of friction stir welded joint of AA202-T3 aluminum alloy[j]. Corros. Sci., 2010, 53(2): [] Xu G, Cao C N, Lin H C, et al. Electrochemical study of active dissolution for aluminum in neutral NaCl solution[j]. Corros. Sci. Prot. Technol., 1998, 10(6): (¼,» Õ, Ç. ÄÏÝ NaCl À Æ Ù ß [J].» ÙÀ, 1998, 10(6): ) [5] Qi G T, Guo Z H, Wei B K, et al. The effect of waterquenching on microstructure and electrochemistry performance of Al-Zn-Sn-Mg anode[j]. Trans. Met. Heat Treat., 2000, 21(): (Å», Ï, ². ÁĐ Al-Zn-In-Sn-Mg Ñ»«Ù ºÚ [J]. Á, 2000, 21(): 68-72) [6] Cao C N. Principles of Electrochemistry[M]. Beijing: Chemical Industry Press, 2007 (» Õ. Ù Ó [M]. : ¹, 200) [7] Wen J B, Wang G W, Ma J L, et al. Effect of gallium on electrochemical properties of Al-Zn-Sn alloy anode[j]. Trans. Met. Heat Treat., 2010, 31(8): (, Ù, È. Ga Đ Al-Zn-Sn ÑÉ Ù ºÚ [J]. Å Á, 2010, 31(8): 30-33) [8] Zhu H W, Qu X Y, Hu Y, et al. Corrosion inhibition of flaky aluminum powders prepared through sol-gel process[j]. Corros. Sci., 2010, 53(1): [9] Abedin S Z E, Enders F. Electrochemical behavior of Al, Al-In and Al-Ga-In alloys in chloride solutions containing zinc ions[j]. J. Appl. Electrochem., 200, 3(10): [10] Dean J A. Lange s Chemistry Handbook[M]. American: McGraw-Hill, 2003 [11] Naeini M F, Shariat M H, Eizadjou M. On the chlorideinduced pitting of ultra fine grains 5052 aluminum alloy produced by accumulative roll bonding process[j]. J. Alloys Compd., 2011, 509(1): [12] Liu G L. Study of stress corrosion mechanism of Ti alloys by recursion method[j]. Acta Metall. Sin., 2007, 3(3): (Ê. Ò «É [J]., 2007, 3(3): ) [13] Ei Shabyeb H A, Abd Ei Vahab F M. Effect of gallium ions on the electrochemical behavior of Al-Sn and Al-Sn- Zn alloys in chloride solution[j]. Corros. Sci., 2001, 3(): [1] Bessone J B, Flamini D O, Saidman S B. Comprehensive model for the activation mechanism of Al-Zn alloys produced by indium[j]. Corros. Sci., 2005, 7(1): [15] Li W, Li D Y. Influence of surface morphology on corrosion and electronic behavior[j]. Acta Mater., 2006, 5(2): 5-52 [16] Zaid B, Saidi D, Benzaid A, et al. Effects of ph and chloride concentration on pitting corrosion of AA6061 aluminum alloy[j]. Corros. Sci., 2008, 50:

5 5 : Al-Zn-Sn-Ga ÐÈ 11 MECHANISM OF PITTING CORROSION ACTIVATION AND PASSIVATION OF Al-Zn-Sn-Ga ALLOY LI Junfeng, WEN Jiuba, HE Junguang, MA Jingling, LI Gaolin School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang Abstract: The micro developed and passivated process of corrosion pits of Al-Zn-Sn-Ga alloy were investigated by SEM, and the function relationship between ph value and pits depth in corrosion pits was also calculated in order to explain the expanded and passivated mechanism of pitting corrosion under the condition of neutral NaCl solution. The result showed that ph value increased along with the expanding of the depth of corrosion pits. However in the range of 0 10 cm, the ph variation was minimal. The cathodic reaction, which could lead to passivation of corrosion pits, gradually became faster because of the activation of Ga amalgam. The passivation depth of corrosion pits was about 10 5 cm. Key words: pitting corrosion, self-catalysis, passivation, amalgam