Title

以Ca2+/HCO3–化成法於鎂合金表面製備Calcitic CaCO3硬質層及其抗腐蝕之研究

Translated Titles

Formation of calcite hard conversion coating on Mg alloy in aqueous Ca2+/HCO3– to protect ally against corrosion

DOI

10.6845/NCHU.2009.00397

Authors

潘信良

Key Words

鎂合金 ; 化成處理 ; 碳酸鈣 ; 電化學 ; Magnesium alloy ; conversion coating ; CaCO3 ; electrochemical

PublicationName

中興大學材料科學與工程學系所學位論文

Volume or Term/Year and Month of Publication

2009年

Academic Degree Category

碩士

Advisor

汪俊延

Content Language

繁體中文

Chinese Abstract

本實驗試圖提供AZ91D 鎂合金試片一種綠色環保的硬質化成皮膜處理法。利用回收之CO2氣體制備含鈣之碳酸水溶液以做為鎂合金處理液。AZ91D鎂合金經50℃含鈣碳酸溶液化成處理2小時,其表面會形成雙層結構Calcite/Mg,Al-hydroralcite的碳酸鈣硬質層。電化學試驗得知,AZ91D鎂合金基材平均腐蝕電流密度為95 μA/cm2;而表面具碳酸鈣硬質層之AZ91D鎂合金平均腐蝕電流密度可下降至7 μA/cm2。鹽霧試驗結果顯示︰碳酸鈣硬質層經鹽霧測試12小時,試片表面出現腐蝕斑點。經300℃高溫爐熱處理去除表面水分之碳酸鈣硬質層,其硬質層在鹽霧測試192小時內,試片表面無腐蝕斑點跡象。交流阻抗試驗得知︰未經熱處理之碳酸鈣硬質層其阻抗為12000歐姆;經300℃高溫爐熱處理之碳酸鈣硬質層卻下降至7800歐姆。經300℃高溫爐熱處理前與熱處理後之碳酸鈣硬質層,其Nyquist圖皆有2個半圓和一個電感曲線。高頻區代表Calcite硬質層電容阻抗,中頻區代表Mg,Al-hydrotalcite電容阻抗,且等效模擬電路圖皆套用相同公式。由刮痕試驗可知長有碳酸鈣皮膜之AZ91D試片的摩擦力低於基材AZ91D。碳酸鈣硬質層不但可以增加AZ91D鎂合金抗腐蝕性,亦可提高AZ91D鎂合金表面耐摩耗性。

English Abstract

The study explores a green environmental protection method for the formation of Mg conversion coating.Ca2+/HCO3–aqueous solution was prepared by bubbling recycling CO2 gas through deionized water.A calcite CaCO3/Mg, Al–hydrotalcite two-layer coating was developed on Mg alloy AZ91D in a Ca2+/HCO3– aqueous solution. The electrochemical experimental results revealed that corrosion current density of the as-diecast AZ91D was 95 uA/cm2. The corrosion current density calcite CaCO3 coated sample was reduced approximately 7 uA/cm2. Results of salt spray test revealed that the as-diecast AZ91D sample surface had several corrosion-rusted regions after 12 hours of salt spray test. Calcite hard conversion coating was happened dehydration at 300℃ heat treatment, the rusted area after a 192 hour salt spray test on the calcite-coated sample was absent. Results of AC impedance tests that the calcite-coated sample capacitive resistance was 12000 ohm. The 300℃ heat treatment of calcite-coated sample capacitive resistance was reduced approximately 7800 ohm. The 300℃ heat treatment and no heat treatment of calcite-coated sample all had two capacitive resistance loop. The high frequency loop was calcite hard conversion coating of capacitive resistance. The low frequency loop was Mg, Al–hydrotalcite interlayer of capacitive resistance. Equivalent circuit for impedance spectra with the 300℃ heat treatment and no heat treatment of calcite-coated sample are same. Results of scratch test that the calcite-coated sample had low friction force than the as-diecast AZ91D. Therefore, calcite hard conversion coating protected AZ91D magnesium alloy against corrosion and reached high wear resistance.

Topic Category 工學院 > 材料科學與工程學系所
工程學 > 工程學總論
Reference
  1. 2. D. R. Lide:Handbook of Chemistry and Physics, 71st ed., CRC, Cleveland, (1991), pp. 8-1-8-57..
    連結:
  2. 3. M. Avedesian and H. Baker:Magnesium and magnesium alloys, ASM Specialty Handbook, ASM, Metals Park, Olio, (1999), pp. 194-210.
    連結:
  3. 6. G. Hanko, H. Antrekowitsch and P. Ebner, Recycling automotive magnesium scrap, JOM, February 54(2002), pp. 51-54.
    連結:
  4. 12. K. Brunelli, M. Dabala, I. Calliari and M. M agrini, Corrosion science, 47, 2005, pp.989.
    連結:
  5. 14. R. A. Berner, Chmical diagensis of some modem carbonate sediments, Am. J. Sci. 264(1996), pp.64-69.
    連結:
  6. 16. H. Roques and A. Girou Water Res. 8 (1974), pp. 907
    連結:
  7. 17. M. Pourbaix, Atlas of electrochemical equilibria in aqueous solutions, National Association of Corrosion Engineers, Houston, 1974, pp. 139-145.
    連結:
  8. 18. M.M. Reddy, G.H. Nancollas, J. Cryst. Growth, 35 (1976) 33.
    連結:
  9. 19. F.C. Meldrum, S.T. Hyde, J. Cryst. Growth, 231 (2001) 544.
    連結:
  10. 20. 鄭凱勵,“Mg,Al-hydrotalcite皮膜的組成結構分析及於鎂合金表面之抗腐蝕特性研究”,國立中興大學材料科學與工程研究所碩士學位論文.
    連結:
  11. 24. Y. Zhang, R. Dawe, Applied Geochemistry, Vol. 13(1998), pp. 177-184.
    連結:
  12. 30. M.E. Berndt, W.E. Seyfried, Geochimica et Cosmochimica Acta, Vol. 63(1999), pp
    連結:
  13. 1. I.J. Polmear, Light Alloy 3rd ed., Arnold, London, pp. 17-18 (1995).
  14. 4. C.S. Lin, C.Y. Lee, W.C. Li, Y.S. Chen, G.N. Fang, Journal of the Electrochemical Society, 153, 2006, pp.B90.
  15. 5. M.P. Antony, V.D. Tathavadkar, C.C. Calvert, A. Jha, Metallurgical and Materials Transactions B, 32, 2001, pp.98.
  16. 7. K.Z. Chong and T.S. Shih, Mater. Chem. Phys., 80(2003), pp. 34-38
  17. 8. M.A. Gonzalez-nubez, P. Skeldon, G.E. Thompson and H. Karimzadeh, Corrosion, 55(1999), pp. 1136-1143.
  18. 9. C.S. Lin and S.K. Fang, J. Elecrvchem. Soc., 152(2005), pp. 54-59.
  19. 10. R. Arrabal, E. Matykina, T. Hashimoto, P. Skeldon and G.E. Thompson, Surface and Coatings Technology, Vol. 203(2009), pp. 2207-2220.
  20. 11. J.E. Gray and B Luan, Journal of Alloys and Compounds, Vol. 336(2002), pp. 88-113.
  21. 13. M. Zhao, S. Wu, J. Luo, Y. Fukuda, H. Nakae, Surface and Coatings Technology, 200, 2006, pp.5407.
  22. 15. Y. Kojima, A. Sadotomo, T. Yasue, Y. Arai, J.Ceramic Soc. Japan Int. Ed. 100(1992), pp. 1128–1135.
  23. 21. F. Kovanda, K. Jiratova, J. Ryme and D. Kolousek, Applied Clay Science, Vol. 18 (2001), pp. 71-80.
  24. 22. M.R. Kang, H.M. Lim, S.C. Lee, S.H. Lee, K.J. Kim, Azojomo Journal of Materials Online, Vol. 1(2005) pp. 1-13.
  25. 23. J.E. Gray, B. Luan, Journal of Alloys and Compounds, 336(2002), pp. 88-113.
  26. 25. S.F. Shanon, J.K. Galinat, S.S. Bang, Biology and Biochemistry, Vol. 31(1999), pp. 1563-1571
  27. 26. J.L. Polo, E. Cano and J.M. Bastidas, Journal of Electroanalytical Chemistry, Vol. 537(2002), pp. 183-187.
  28. 27. Pao-Chi Chen, Clifford Y. Tai and K. C. Lee, Chem. Eng. Science, Vol. 52 (1997), pp. 4171-4177
  29. 28. Jun-Yen Uan, Bing-Lung Yu, Xin-Liang Pan, Metall. Mater. Trans. A. Vol. 39(2008), pp. 3233-3245.
  30. 29. Yuping Zhang, Richard A. Dawe, Chemical Geology, 163 (2000), pp. 129-138.