CORROSÃO POR PITE EM CONDIÇÃO EROSIVA DA LIGA CU10NI-3AL-1,3FE ENVELHECIDA A 550°C, EM MEIO CONTENDO SULFATO
PITTING CORROSION IN EROSIVE CONDITION OF AGED 550°C CU10NI-3AL-1,3FE ALLOY IN 0,01 M NA2SO4
Liberto, Rodrigo Nascimento; Magnabosco, Rodrigo; Alonso-Falleiros, Neusa
http://dx.doi.org/10.4322/tmm.2012.025
Tecnol. Metal. Mater. Min., vol.9, n3, p.173-181, 2012
Resumo
O presente trabalho avalia o efeito do envelhecimento a 550°C sobre a corrosão por pite da liga Cu10Ni-3Al‑1,3Fe, através de ensaios de polarização em solução aquosa 0,01 M Na2SO4 em condição erosiva. Após laminação a frio, as amostras foram solubilizadas a 900°C por 1 hora, e envelhecidas a 550°C por até 1.032 horas. A investigação foi realizada por polarização potenciodinâmica, em eletrólito constituÃdo de 0,01 M Na2SO4 com 10% em massa de partÃculas abrasivas de Al2O3. As amostras ensaiadas foram analisadas pelas técnicas de microscopia óptica (MO) e de microscopia eletrônica de varredura (MEV), a fim de se examinar a morfologia da degradação. Os resultados mostram que todas as condições de tratamento térmico apresentam um potencial de quebra de passividade (Eq), que caracteriza o inÃcio do processo de corrosão por pite. No entanto, não se observam alterações significativas do valor de Eq em função do tempo de envelhecimento. O mecanismo de corrosão por pite na liga estudada pode ter ocorrido pela quebra da passividade por ação do Ãon sulfato, seguida de crescimento do pite por ação galvânica e/ou dissolução do cobre em Ãons cuprosos e cúpricos e com formação de membrana de óxido cuproso sobre do pite.
Palavras-chave
Liga cobre-nÃquel-ferro, Corrosão por pites, Corrosão por erosão.
Abstract
This study evaluates the effect of aging at 550°C on pitting corrosion of Cu10Ni-3Al-1.3Fe alloy, after potentiodynamic polarization test in 0.01 M Na2SO4 in erosive condition. Cold rolled sheet specimens were solution treated at 900°C for 1 hour, and aged at 550°C until 1,032 hours. The investigation was carried out by potentiodynamic polarization in electrolyte consisted of 0.01 M Na2SO4 with 10 wt. (%) of Al2O3 abrasive particles. After the polarization tests, specimens were analyzed by optical microscopy and scanning electron microscopy techniques to examine the morphology of the corroded regions. Result show that all samples present a passivity break potential (Eq) that characterizes the initiation of pitting corrosion. However, it is not observed any significant change in the value of passivity break potential as a function of aging time. The mechanism of pitting corrosion in the studied alloys can be the passivity breakdown by the action of sulfate ion, followed by growth of pit by galvanic action or dissolution of the copper in cupric and cuprous ions and membrane formation of cuprous oxide over the pit.
Keywords
Cupronickel alloys, Pitting corrosion, Erosion-corrosion
Referências
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2 UHLIG, H. H. Corrosion and corrosion control. 3. ed. New York: John Wiley & Sons, 1985.
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4 NEWTON, J.; WILSON, C. L. Metallurgy of copper. New York: John Wiley & Sons, 1987.
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10 TUCK, C. D. S. High-strength cupronickel alloy resists corrosion. Advanced Materials & Processes, v. 5, n. 11, p. 8, Nov. 1996.
11 BARTON, E. Strong copper-nickel alloy resists marine corrosion. Advanced Materials & Processes, v. 153, n. 3, p. 8, 1998.
12 MATHIYARASU, J.; PALANISWAMY, N.; MURALIDHARAN, V. S. An insight into the passivation of cupronickel alloys in chloride environment. Journal Chemical Sciences, v. 113, n. 1, p. 63-76, Feb. 2001. http://dx.doi.org/10.1007/ BF02708553
13 SYRETT, B. A. Erosion-corrosion of copper-nickel alloys in sea water and other aqueous environments: a literature review. Corrosion, v. 32, n. 6, p. 242-52, 1976.
14 DEXTER, S. C. Localized corrosion. In: AMERICAN SOCIETY FOR METALS. Metals handbook. 9. ed. Metals Park, 1990. V. 13: Corrosion, p. 104-22.
15 SANCHEZ, S. R; SIMISON, S.; MANFREDI, C. Selection of copper base alloys for use in polluted seawater. Corrosion, v. 43, n. 8, p. 458-64, 1987. http://dx.doi.org/10.5006/1.3583885
16 SZKLARSKA-SMIALOWSKA, Z. Pitting corrosion of metals. Houston, Nace, 1986.
17 YABUKI, A.; MURAKAMI, M. Critical ion concentration for pitting and general corrosion of copper. Corrosion (Houston), v. 63, n. 3, p. 249-57, 2007. http://dx.doi.org/10.5006/1.3278349
18 LIBERTO, R. C. N.; FALEIROS, N. A.; MAGNABOSCO, R. Selective corrosion in sodium chloride aqueous solution of cupronickel alloys with aluminum and iron additions. Corrosion (Houston), v. 63, p. 211-9, 2007. http://dx.doi. org/10.5006/1.3278345
19 LIBERTO, R. C. N.; MAGNABOSCO, R.; ALONSO-FALLEIROS, N. Selective corrosion of 550°C aged Cu10Ni-3Al- 1.3Fe alloy in NaCl aqueous solution. Corrosion Science, v. 53, n. 5, p. 1976-82, May 2011.
20 LIBERTO, R. C. N. Corrosão-erosão da liga Cu10Ni-3Al-1,3Fe em presença de Ãons cloreto, sulfato e sulfeto. 2010. 215 f. Tese (Doutorado em Engenharia Metalúrgica e de Materiais) − Escola Politécnica da Universidade de São Paulo, São Paulo, 2010.
21 LUCEY, V. F. Mechanism of pitting corrosion of copper in supply waters. British Corrosion Journal, v. 2, n. 5, p. 175-85, Sep.1967. http://dx.doi.org/10.1179/000705967798326731
2 UHLIG, H. H. Corrosion and corrosion control. 3. ed. New York: John Wiley & Sons, 1985.
3 BAILEY, G. L. Copper-nickel-iron alloys resistant to seawater corrosion. The Journal of the Institute of Metals, p. 243-92, July 1951.
4 NEWTON, J.; WILSON, C. L. Metallurgy of copper. New York: John Wiley & Sons, 1987.
5 ROBINSON, P. Properties of wrought coppers and copper alloys. In: AMERICAN SOCIETY FOR METALS. Metals handbook. 10. ed. Metals Park, 1992. V. 2: Properties and selection, p. 338-41.
6 HARRINGTON, R. L. Marine engineering. New York: The Society of Naval Architects and Marine Engineers, 1971.
7 SHREIR, L. L. Corrosion. 2. ed. London: Newnes-Butterworths, 1977. v. 1.
8 MUSSOI, C. R. S.; SERRA, E. T.; ARAÚJO, A. A. Failures in 90-10 copper-nickel heat exchangers caused by underdeposit corrosion. In: ANNUAL INTERNATIONAL CONGRESS OF ABM, 58., 2003, Rio Janeiro. Anais… São Paulo: ABM, 2003. p. 383-92.
9 BENDAL, K. C. A longer life in the ocean waves. Materials World, v. 5, n. 12, p. 711-3, Dec. 1997.
10 TUCK, C. D. S. High-strength cupronickel alloy resists corrosion. Advanced Materials & Processes, v. 5, n. 11, p. 8, Nov. 1996.
11 BARTON, E. Strong copper-nickel alloy resists marine corrosion. Advanced Materials & Processes, v. 153, n. 3, p. 8, 1998.
12 MATHIYARASU, J.; PALANISWAMY, N.; MURALIDHARAN, V. S. An insight into the passivation of cupronickel alloys in chloride environment. Journal Chemical Sciences, v. 113, n. 1, p. 63-76, Feb. 2001. http://dx.doi.org/10.1007/ BF02708553
13 SYRETT, B. A. Erosion-corrosion of copper-nickel alloys in sea water and other aqueous environments: a literature review. Corrosion, v. 32, n. 6, p. 242-52, 1976.
14 DEXTER, S. C. Localized corrosion. In: AMERICAN SOCIETY FOR METALS. Metals handbook. 9. ed. Metals Park, 1990. V. 13: Corrosion, p. 104-22.
15 SANCHEZ, S. R; SIMISON, S.; MANFREDI, C. Selection of copper base alloys for use in polluted seawater. Corrosion, v. 43, n. 8, p. 458-64, 1987. http://dx.doi.org/10.5006/1.3583885
16 SZKLARSKA-SMIALOWSKA, Z. Pitting corrosion of metals. Houston, Nace, 1986.
17 YABUKI, A.; MURAKAMI, M. Critical ion concentration for pitting and general corrosion of copper. Corrosion (Houston), v. 63, n. 3, p. 249-57, 2007. http://dx.doi.org/10.5006/1.3278349
18 LIBERTO, R. C. N.; FALEIROS, N. A.; MAGNABOSCO, R. Selective corrosion in sodium chloride aqueous solution of cupronickel alloys with aluminum and iron additions. Corrosion (Houston), v. 63, p. 211-9, 2007. http://dx.doi. org/10.5006/1.3278345
19 LIBERTO, R. C. N.; MAGNABOSCO, R.; ALONSO-FALLEIROS, N. Selective corrosion of 550°C aged Cu10Ni-3Al- 1.3Fe alloy in NaCl aqueous solution. Corrosion Science, v. 53, n. 5, p. 1976-82, May 2011.
20 LIBERTO, R. C. N. Corrosão-erosão da liga Cu10Ni-3Al-1,3Fe em presença de Ãons cloreto, sulfato e sulfeto. 2010. 215 f. Tese (Doutorado em Engenharia Metalúrgica e de Materiais) − Escola Politécnica da Universidade de São Paulo, São Paulo, 2010.
21 LUCEY, V. F. Mechanism of pitting corrosion of copper in supply waters. British Corrosion Journal, v. 2, n. 5, p. 175-85, Sep.1967. http://dx.doi.org/10.1179/000705967798326731
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