釩酸根對 AZ31 和 AZ91 鎂合金硝酸鈰化成皮膜結構與性質之影響

Influence of Vanadate Additive on the Structure and Properties of Cerium Conversion Coatings on AZ31 and AZ91 Magnesium Alloys

10.6342/NTU.2013.01382

羅文昕

AZ31 鎂合金 ； AZ91 鎂合金 ； 鈰鹽化成處理 ； 釩酸鹽化成處理 ； 抗蝕性 ； AZ31 magnesium alloys ； AZ91 magnesium alloys ； cerium conversion coating ； vanadate conversion coating ； corrosion resistance

國立臺灣大學材料科學與工程學系學位論文

2013年

碩士

林招松

繁體中文

鎂合金應用日益廣泛，但因過去大量使用之六價鉻化成溶液，對人體及環境會造成危害，近年來大量研究投入發展鎂合金化成系統之替代溶液。其中以稀土鹽類中之鈰鹽具有抑制金屬腐蝕效果，為一主要發展研究之方向。然而鈰鹽系統化成反應時間較長，添加過氧化氫可有效提升反應速率，卻又因加速反應使得氫氣泡大量生成，造成具表面缺陷之皮膜結構，缺陷面積高達 58 %。為抑制缺陷形成獲得良好性質之鈰鹽化成皮膜，藉添加釩酸鹽至鈰鹽化成溶液中，以獲得一緻密性、附著性及抗蝕性皆佳之皮膜。本研究針對，直接添加釩酸鹽及先行調整釩酸鹽 pH 值後之鎂合金鈰鹽化成皮膜，進行微結構、電化學分析與鹽霧試驗抗蝕性評估。 結果顯示直接添加釩酸鹽之鈰鹽化成溶液，雖溶液易發生 CeO2 沉澱，但此混合化成溶液適當之化成反應速率，可產生較薄但緻密、附著性佳，且表面缺陷少之雙層結構化成皮膜。由電化學及鹽霧分析上，抗蝕性有大幅提升。此外，增加添入釩酸鹽之濃度可獲得更佳之抗蝕性皮膜。為提升此混合化成溶液穩定性，先行調整釩酸鹽溶液 pH 值後再添加成混合化成溶液，可於化成短時間內獲得較高抗蝕性之化成薄膜，同時，抑制缺陷形成，皮膜缺陷面積僅 36 %，單位面積缺陷也具縮小之趨勢。透過比較添加不同濃度以及調整 pH 值所得之鈰-釩酸鹽混合化成溶液，本研究討論不同系統之化成皮膜成長機制以及缺陷成因，藉結果提出最佳之鎂合金鈰-釩混合化成皮膜之可能改良方案。

Magnesium-based alloys have attracted many attentions these years because of their outstanding properties. However, the inadequate corrosion resistance limits the application of magnesium and its alloys. Many studies have established the feasibility of the conversion coating of rare earth metal salts on Mg alloys. Especially, the characteristic of inhibition of metal corrosion by cerium salt extends the research interest in the field of conversion coating. However, a long period of conversion time is necesssary to from a cerium conversion coating. Although adding H2O2 accelerates the conversion rate, the excess hydrogen evolution leads to the blisters on the coating, which has a blister area of 58 %. The present study adds metavanadate into cerium-based conversion solution in order to obtain a conversion coating with dense structure for improved adhesion and corrosion resistance. The analyses of microstructure observations, EIS and salt spray test are conducted to investigate the conversion coating on AZ31 and AZ91. The results indicate the conversion solution containing metavanadate produces a thin bilayered coating without blisters on Mg alloys. The corrosion resistance is improved significantly. Moreover, increasing the concentration of metavanadate promotes the influence of vanadate on the properties of the conversion coating. Furthermore, this work adjusts the pH value of metavanadate solution prior to the addition to the conversion solution, for improving the stability of conversion solution. Adding the solution of metavanadate with pH 2.8-2.9, the conversion coating exhibits good corrosion resistance within short conversion times. Meanwhile, the formation of defect is inhibited. The surface defects area can be reduced to 36 %, and the size of each blister becomes much smaller. The present study compares the different cerium-based conversion coatings with adding metavanadate. Finally, the mechanisms of conversion and defect formation are discussed in details.

1. 1. S. Mathieu, C. Rapin, J. Steinmetza and P. Steinmetz, “A Corrosion Study of the Main Constituent Phases of AZ91 Magnesium Alloys,” Corros. Sci., 45, 2741-2755 (2003)
   連結：
2. 2. C. H. Caceres, C. J. Davidson, J. R. Griffiths and C. L. Newton, “Effects of solidification rate and ageing on the microstructure and mechanical proper AZ91 alloy,” Mater. Sci. Eng., A325, 344-355 (2002)
   連結：
3. 3. J. E. Gray and B. Luan, “Protective Coatings on Magnesium and its alloys- a critical Review,” J. Alloys Compd., 336, 88-113 (2002)
   連結：
4. 4. Y. Kojima, “Project of plat form science and technology for advanced magnesium alloys,” Mater. Trans., 42, 1154-1159 (2001)
   連結：
5. 8. A. J. Bard and L. R. Faulkner, Electrochemical Methods, Fundamentals and Applications, 2nd ed, John Wiley & Sons, Inc. press, University of Texas at Austin, (2001)
   連結：
6. 10. J. H. Nordlien, S. One and N. Masuko, “Morphology and structure of oxide films formed on magnesium by exposure to air and water,” J. Electrochem. Soc., 142, 3320-3322 (1995)
   連結：
7. 11. M. Pourbaix, “Atlas of Electrochemical Equilibria in Aqueous aolution,” NACE (1974)
   連結：
8. 12. E. Ghali, W. Dietze and K. Kainer, “General and localized corrosion of magnesium alloys: a critical review,” J. Mater. Eng. Perform., 13, 7-23 (2004)
   連結：
9. 14. Binary Alloy Phase Diagrams, American Society for Metals, Park, Ohin, (1986)
   連結：
10. 15. G. Song, A. Atrens, X. Wu and B. Zhang, “Corrosion behaviour of AZ21, AZ50 and AZ91 in sodium chloride,” Corros. Sci., 40, 1769-1791 (1998)
    連結：
11. 16. H. Zhang, G. Yao, S. Wang, Y. Liu and H. Luo, “A chrome-free conversion coating for magnesium–lithium alloy by a phosphate–permanganate solution, ” Surf. Coat. Technol., 202, 1825-1830 (2008)
    連結：
12. 17. 李偉任，｢AZ31 鎂合金硝酸鈰化成皮膜結構與性質研究｣，臺灣大學博士論文，2008 年 7 月
    連結：
13. 18. C. S. Lin and W. J. Li, “Corrosion Resistance of Cerium-Conversion Coated AZ31 Magnesium Alloys in Cerium Nitrate Solutions,” Mater. Trans., 47, 1020-1025 (2006)
    連結：
14. 19. K. Brunelli, M. Dabalá, I. Calliari and M. Magrini, “Effect of HCl pre-treatment on corrosion resistance of cerium-based conversion coatings on magnesium and magnesium alloys,” Corros. Sci., 47, 989-1000 (2005)
    連結：
15. 20. L. Yang, B. Luan, W. Cheong and D. Shoesmith, “Sono-Immersion Deposition on Magnesium Alloy,” J. Electrochem. Soc., 152, C131-136 (2005)
    連結：
16. 21. C. K. Mittal, “Chemical Conversion and Anodized Coatings,” Trans. Met. Finish. Assoc. India, 4, 227 -231 (1995)
    連結：
17. 24. S. Ono, Y. Suzuki, H. Asoh, N. Hanzawa and M. Hyakutake, “Microstructure of Anodic Films Grown on Magnesium-Lithium-Yttrium Ultra Light Alloy,” Mater. Sci. Forum, 581, 426- 432 (2003)
    連結：
18. 25. H. Y. Hsiao and W. T. Tsai, “Characterization of anodic films formed on AZ91D magnesium alloy,” Surf. Coat. Technol., 190, 299-308 (2005),.
    連結：
19. 26. H. Y. Hsiao, H. C. Tsung and W. T. Tsai, “Anodization of AZ91D magnesium alloy in silicate-containing electrolytes,” Surf. Coat. Technol., 199, 127-134 (2005)
    連結：
20. 27. H. Y. Hsiao and W. T. Tsai, “Effect of heat treatment on anodization and electrochemical behavior of AZ91D magnesium alloy,” J. Mater. Res., 20, 2673-2771 (2005)
    連結：
21. 28. W. K. Chen, J. L. Lee, C. M. Liu, J. Y. Wang and M. D. Ger, “The Electrochemical Corrosion Properties of Anodic Film on Magnesium Alloy LZ91 by Pulse Method,” The 2004 Annual Conference of the Chinese Society for Material Science, Taiwan (2004)
    連結：
22. 31. G. E. Thompson, K. Shimizu and G. C. Wood, “Observation of flaws in Anodic Films on Aluminum,” Nature, 286, 471-472 (1980)
    連結：
23. 32. F. W. Eppensteiner and M. R. Jenkins, Metal Finishing Guidebook and Directory, (1992)
    連結：
24. 34. Material Safety Data Sheets, CAS. No. 07738-94-5.
    連結：
25. 35. J. I. Skar, L. K. Sivertsen and J. M. Oster, “Chrome-free conversion coating for Magnesium die castings-a review,” ICEPAM, (2004)
    連結：
26. 36. 李威志，｢AZ31 鎂合金之磷酸鹽/過錳酸鹽化成皮膜微結構與成長機制探討｣台灣大學碩士論文，2005 年 7 月。
    連結：
27. 37. C. S. Lin, C. Y. Lin, W. C. Li, Y. S. Chen and G. N. Fang, “Formation of Phosphate/Permanganate Conversion Coating on AZ31 Magnesium Alloy,” J. Electrochem. Soc., 153, B90-96 (2006)
    連結：
28. 38. Y. L. Lee, Y. R. Lee, C. W. Li and C. S. Lin, “Effect of permanganate concentration on the formation and properties of phosphate/permanganate conversion coating on AZ31 magnesium alloy,” Corros. Sci., 70, 74-81 (2013)
    連結：
29. 39. M. Mosiałek, G. Mordarski, P. Nowak, W. Simka, G. Nawrat, M. Hanke, R. P. Socha and J. Michalska, “Phosphate–permanganate conversion coatings on the AZ81 magnesium alloy: SEM, EIS and XPS studies,” Surf. Coat. Technol., 206, 51-62 (2011)
    連結：
30. 41. H. Zhang, G. Yao, S. Wang, Y. Liu and H. Luo, “A chrome-free conversion coating for magnesium–lithium alloy by a phosphate–permanganate solution,” Surf. Coat. Technol., 202, 1825-1830 (2008)
    連結：
31. 42. Y. C. Yang, C. Y. Tsai, Y. H. Huang, and C. S. Lin, “Formation Mechanism and Properties of Titanate Conversion Coating on AZ31 Magnesium Alloy,” J. Electrochem. Soc., 159, C226-232 (2012)
    連結：
32. 43. T. Ishizaki, Y. Masuda, and N. Saito, “Chemical Deposition and Corrosive Resistance of TiO2/MgF2 Composite Nanofilm on Magnesium Alloy AZ31,” Electrochem. Solid-State Lett., 12, D68-71 (2009)
    連結：
33. 44. L. Zhu, F. Yang and N. Ding, “Corrosion Resistance of The Electro-Galvanized Steel Treated in a Titanium Conversion Solution,” Surf. Coat. Technol., 201, 7829-7834 (2007)
    連結：
34. 45. A. L. Rudd, C. B. Breslin and F. Mansfeld, “The corrosion protection afforded by rare earth conversion coatings applied to magnesium,” Corros. Sci., 42, 275-288 (2000)
    連結：
35. 46. C. S. Lin and S. K. Fang, “Formation of Cerium Conversion Coatings on AZ31Magnesium Alloys,” J. Electrochem. Soc., 152, B54-59 (2005)
    連結：
36. 47. H. Y. Su, W. J. Li, and C. S. Lin, “ Effect of Acid Pickling Pretreatment on the Properties of Cerium Conversion Coating on AZ31 Magnesium Alloy,” J. Electrochem. Soc., 159, C219-225 (2012)
    連結：
37. 49. Y. L. Lee, F. J. Chen and C. S. Lin, “Corrosion resistance studies of cerium conversion coating with a fluoride-free pretreatment on AZ91D magnesium alloy, ” J. Electrochem. Soc., 160, C28-35 (2013)
    連結：
38. 50. Y. L. Lee, Y. R. Chu, F. J. Chen and C. S. Lin, “Mechanism of the formation of stannate and cerium conversion coatings on AZ91D magnesium alloys,” Appl. Surf. Sci., 276, 578-585 (2013)
    連結：
39. 51. C. S. Lin, H. C. Lin, K. M. Lin and W. C. Lai, ”Formation and properties of stannate conversion coatings on AZ61 magnesium alloys,” Corros. Sci., 48, 93-1009 (2006)
    連結：
40. 52. Y. H. Huang, Y. L. Lee, and C. S. Lin, ”Acid Pickling Pretreatment and Stannate Conversion Coating Treatment of AZ91D Magnesium Alloy,” J. Electrochem. Soc., 158, C310-317 (2011)
    連結：
41. 53. H. H. Elsentriecy, K. Azumi and H. Konno, ”Improvement in stannate chemical conversion coatings on AZ91 D magnesium alloy using the potentiostatic technique,” Electrochim. Acta, 53, 1006-1012 (2007)
    連結：
42. 54. H. H. Elsentriecy, K. Azumi and H. Konno, ”Effects of pH and temperature on the deposition properties of stannate chemical conversion coatings formed by the potentiostatic technique on AZ91D magnesium alloy,” Electrochim. Acta, 53, 4267-4275 (2008)
    連結：
43. 55. K. H. Yang, M. D. Ger, W. H. Hwu, Y. Sung and Y. C. Liu, ”Study of vanadium-based chemical conversion coating on the corrosion resistance of magnesium alloy,” Mater. Chem. Phy., 101, 480-485 (2007)
    連結：
44. 56. H. Guan and R. G. Buchheit, ”Corrosion Protection of Aluminum Alloy 2024-T3 by Vanadate Conversion Coatings,” Corros. Sci., 60, 284-296 (2004)
    連結：
45. 57. A. S. Hamdy, I. Doench, and H. Möhwald, ”Vanadia-based coatings of self-repairing functionality for advanced magnesium Elektron ZE41 Mg–Zn–rare earth alloy,” Surf. Coat. Technol., 206, 3686-3692 (2012)
    連結：
46. 58. M. F. Morks, P. A. Corrigan and I. S. Cole, ”Mn-Mg Based Zinc Phosphate and Vanadate for Corrosion Inhibition of Steel Pipelines Transport of CO2 Rich Fluids,” Int. J. of Greenhouse Gas Control, 7, 218-224 (2012)
    連結：
47. 59. Y. Ma, N. Li, D. Li, M. Zhang and X. Huang, ”Characteristics and corrosion studies of vanadate conversion coating formed on Mg–14 wt% Li–1 wt% Al–0.1 wt% Ce alloy,” Appl. Surf. Sci., 261, 59-67 (2012)
    連結：
48. 60. Z. Zou, N. Li, D. Li, H. Liu and S. Mu, ”A vanadium-based conversion coating as chromate replacement for electrogalvanized steel substrates,” J. Alloys Compd., 509, 503-507 (2011)
    連結：
49. 62. ASTM Standard, ”Standard Test Methods for Measuring Adhesion by Tape Test,” D3359-02
    連結：
50. 66. 方思凱，「AZ31 鎂合金之硝酸鈰化成處理」，臺灣大學碩士論文，2004 年 7 月
    連結：
51. 67. B. R. W. Hinton, D. R. Arnot and N. E. Ryan, ”The inhibition of aluminium alloy corrosion by cerous cations,” Met. Forum, 7, 211-217 (1984)
    連結：
52. 68. N. F. W. M. Sidik, M. Z. M. Zamzuri, M. M. Salleh and K. A. Ismail, ”Effect of NaVO3 Concentration on Corrosion Resistance of Conversion Coating on AZ91D Magnesium Alloy,” Adv. Mat. Res., 576, 438-441 (2012)
    連結：
53. 70. K. D. Ralston, S. Chrisanti, T. L. Young and R. G. Buchheit, ”Corrosion Inhibition of Aluminum Alloy 2024-T3 by Aqueous Vanadium Species,” J. Electrochem Soc., 155, C350-359 (2008)
    連結：
54. 5. 楊智超，「鎂合金材料特性及新製程發展」，工業材料，152 期，1999 年
55. 6. 戴光勇，「鎂合金表面處理技術(上)」，材料與社會，24 期，1988 年
56. 7. 戴光勇，「鎂合金表面處理技術(下)」，材料與社會，25 期，1989 年
57. 9. M. Avedesian and H. Baker, Magnesium and Magnesium Alloys, ASM Specialty Hanbook
58. 13. 陳中一，「2007 非鐵金屬特輯-鎂金屬篇」，財團法人金屬工業研究發展中心，2007 年
59. 22. 楊聰仁，「鎂合金非鉻系表面處理技術」，工業材料雜誌，174 期，2001年
60. 23. T. Biestek and J. Weber, “Electrolytic and Chemical Conversion Coating Portcullis Press,” Redhill, 208-210, 306-311 (1976)
61. 29. 李九龍，陽光絢，張進龍，宋鈺，葛明德，｢前處理對鎂合金化成處理之研究｣，中國材料科學學會 2003 年度年會。
62. 30. W. Kobayashi, K. Uehori and M. Furuta, “Anodizing Solution for Anodic Oxidation Article of Magnesium or Its Alloy,” US Patent 4,744,872 (1988)
63. 33. J. Honer, “Chromate Post Treatments,” Metal Finishing, 88, 76-80 (1990)
64. 40. I. Azkarate, P. Cano, A. D. Barrio, M. Insausti and P. S. Coloma, “Alternatives to Cr(VI) conversion coating for magnesium alloys,” International Congress of Magnesium Alloys and Their Applications, Germany, 475-483 (2000)
65. 48. “Fact Sheet－Environment, Health and Safety Information for the Berkeley Campus,“ (2008)
66. 61. ASTM Standard, ”Standard Specification for Magnesium-Alloy Sheet and Plate,” B90/B90M-07
67. 63. ASTM Standard, ”Standard Test Method for Conducting Potentiodynamic Polarization Resistance Measurements,” G59-97
68. 64. ASTM Standard, ”Standard Practice for Operating Salt Spray (Fog) Apparatus,” B117-11
69. 65. ASTM Standard, ”Standard Practice for Evaluating Degree of Rusting on Painted Steel Surface,” D610-08
70. 69. C. F. Baes and R. E. Mesmer, The Hydrolysis of Cation, Wiley, New York, (1976)