EFEITO DE MOLÉCULAS AUTO-ORGANIZÁVEIS NA RESISTÊNCIA À CORROSÃO DA LIGA AA2024-T3
EFFECT OF SELF-ASSEMBLING MOLECULES ON THE CORROSION RESISTANCE OF THE AA2024-T3 ALLOY
Souza, Solange de; Yoshikawa, Daniel Sierra; Assis, Sérgio Luiz de; Santos, Wagner Izaltino A. dos; Costa, Isolda
http://dx.doi.org/10.4322/tmm.00603002
Tecnol. Metal. Mater. Min., vol.6, n3, p.130-135, 2010
Resumo
Revestimentos baseados em moléculas auto-organizáveis (SAM) vêm sendo estudados como possíveis substitutos aos revestimentos de conversão de cromato para proteção contra corrosão em ligas de alumínio. Neste trabalho é investigada a influência de moléculas auto-organizáveis, do grupo dos alcanos difosfonatos, na resistência à corrosão da liga AA2024-T3 utilizando as técnicas de espectroscopia de impedância eletroquímica, polarização potenciodinâmica, ensaios acelerados de corrosão e microscopia eletrônica de varredura. Os resultados mostram que o tratamento da superfície da liga AA2024-T3 com SAM causou o ataque corrosivo e diminuiu sua resistência à corrosão. O tratamento da superfície com solução à base de cromo (VI) também causou ataque na liga e também diminuiu a sua resistência à corrosão. O tratamento que resulta em melhor resistência à corrosão da liga consiste no crescimento e selagem do óxido de alumínio.
Palavras-chave
Moléculas auto-organizáveis, AA2024-T3, Cromatização
Abstract
Coatings based on self-assembling molecules (SAM) have been studied as possible substitutes to the chromate conversion coatings for corrosion protection of aluminium alloys. In this work, the influence of alkane diphosphonates self-assembling molecules on the corrosion resistance of the AA2024-T3 aluminium alloy is investigated. The corrosion investigation is carried out by electrochemical impedance spectroscopy, potentiodynamic polarization techniques, accelerated corrosion experiments and scanning electron microscopy technique. Results show that the surface treatment with self-assembling molecules decreased the corrosion resistance of the alloy due to the corrosive attack of the SAM solution to the alloy surface. The solution used for passivation with chromium (VI) also caused the attack of the alloy surface, leading to slight decreases in the corrosion resistance. The surface treatment that produced the best corrosion resistance is associated with the growth and sealing of the surface oxide.
Keywords
Self-assembling molecules, AA2024-T3, Chromatizing
Referências
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10 OSÓRIO, W.R., et al. The roles of macrosegregation and of dendritic array spacings on the electrochemical behavior of an Al-4.5 wt.% Cu alloys. Electrochimica Acta, v. 52, n. 9, p. 3265-73, Feb. 2007.
11 OSÓRIO, W.R. et al. Corrosion behavior of hypoeutectic Al-Cu alloys in H2SO4 and NaCl solutions. Acta Metallurgica Sinica, v. 22, n. 4, p. 241-6, Aug. 2009.
12 BALTAT-BAZIA, A. et al. Electrochemical impedance spectroscopy and electron microscopies applied to the structure of anodic oxide layers on pure aluminium. Materials Science Forum, v.111-112, p. 359-68, 1992.
13 IZALTINO, W.A.S. et al. Self Assembling Molecules as corrosion inhibitors for 1050 aluminum alloy. In: EUROCORR 2009, Nice, France. Proceedings... Frankfurt: European Federation of Corrosion, 2009.
14 YOSHIKAWA, D.S. et al. Estudo do comportamento de corrosão da liga 5052 tratada com moléculas auto-organizáveis. Tratamento de Superfície, v. 1, n. 155, p. 24-9, Maio/Jun. 2009.
15 DE SOUZA, S. et al. Nanostructured surface pre-treatment based on Self-Assembled Molecules for corrosion protection of Alclad 7475-T761 aluminium alloy. In: INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS, 11; ENCONTRO DA SBPMAT, 8., 2009, Rio de Janeiro. Rio de Janeiro: Sociedade Brasileira de Pesquisa em Materiais, 2009. 1 CD-Rom.
2 DE SOUZA, S. Smart coating based on polyaniline acrylic blend for corrosion protection of different metals. Surface and Coatings Technology, v. 201, n. 16-17, p. 7574-81, May 2007.
3 REIS, F.M.; MELO, H.G.; COSTA, I. EIS investigation on Al 5052 alloy surface preparation for self-assembling monolayer. Electrochimica Acta, v. 51, n. 8-9, p. 1780-8, Jan. 2006.
4 HINTZE, P.E.; CALLE, L.M. Electrochemical properties and corrosion protection of organosilane self-assembled monolayers on aluminium 2024-T3. Electrochimica Acta, v. 51, n. 8-9, p. 1761-66, Jan., 2006.
5 SCHREIBER, F. Structure and growth of self-assembling monolayers. Progress in Surface Science, v. 65, n. 5-8, p. 151-256, Dec. 2000.
6 STEWART, K.R. et al. Improved adhesion of thin conformal organic films to metal surface. Reviews of Scientific Instruments, v. 57, n. 7, p. 1381-3, Mar. 1986.
7 MAEGE, I. et al. Self-assembling adhesion promoters for corrosion resistant metal polymer interface. Progress In Organic Coatings, v. 34, n. 1-4, p.1-12, July 1998.
8 ULMAN, A. Thin film “organic thin films and surfaces: directions for the nineties”. New York: Academic Press, 1995.
9 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION. Norma ISO 8501 - 1:1988. Preparation of steel substrates before application of paints and related products: visual assessment of surface cleanliness. Part 1: Rust grades and preparation grades of uncoated steel substrates and of steel substrates after overall removal of previous coatings. Disponível em: http://www.iso.org/iso/iso_catalogue/catalogue_ics/ catalogue_detail_ics.htm?csnumber=15711&ICS1=25&ICS2=220&I CS3=10. Acesso em: 20 fev. 2009.
10 OSÓRIO, W.R., et al. The roles of macrosegregation and of dendritic array spacings on the electrochemical behavior of an Al-4.5 wt.% Cu alloys. Electrochimica Acta, v. 52, n. 9, p. 3265-73, Feb. 2007.
11 OSÓRIO, W.R. et al. Corrosion behavior of hypoeutectic Al-Cu alloys in H2SO4 and NaCl solutions. Acta Metallurgica Sinica, v. 22, n. 4, p. 241-6, Aug. 2009.
12 BALTAT-BAZIA, A. et al. Electrochemical impedance spectroscopy and electron microscopies applied to the structure of anodic oxide layers on pure aluminium. Materials Science Forum, v.111-112, p. 359-68, 1992.
13 IZALTINO, W.A.S. et al. Self Assembling Molecules as corrosion inhibitors for 1050 aluminum alloy. In: EUROCORR 2009, Nice, France. Proceedings... Frankfurt: European Federation of Corrosion, 2009.
14 YOSHIKAWA, D.S. et al. Estudo do comportamento de corrosão da liga 5052 tratada com moléculas auto-organizáveis. Tratamento de Superfície, v. 1, n. 155, p. 24-9, Maio/Jun. 2009.
15 DE SOUZA, S. et al. Nanostructured surface pre-treatment based on Self-Assembled Molecules for corrosion protection of Alclad 7475-T761 aluminium alloy. In: INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS, 11; ENCONTRO DA SBPMAT, 8., 2009, Rio de Janeiro. Rio de Janeiro: Sociedade Brasileira de Pesquisa em Materiais, 2009. 1 CD-Rom.
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