DEPOSIÇÃO ELETROASSISTIDA DE ORTOSSILICATO DE TETRAETILA (TEOS) COMO PRÉ-TRATAMENTO PARA A PINTURA DE ALUMÍNIO AA1100
TETRAETHYL ORTHOSILICATE (TEOS) ELECTRO-ASSISTED DEPOSITION AS A PRETREATMENT FOR PAINTING AA1100 ALUMINUM ALLOY
Moreira, Vitor Bonamigo; Cardoso, Henrique Ribeiro Piaggio; Ferreira, Jane Zoppas; Meneguzzi, Álvaro
Resumo
A técnica convencional de produção de filmes de organossilanos por imersão pode promover a formação de pré-tratamentos pouco homogêneos, prejudicando a sua proteção por barreira contra a corrosão e a aderência de tintas. Sendo assim, a técnica de deposição eletroassistida, baseada na promoção da eletrólise da água e consequente favorecimento das reações de condensação do organossilano, é estudada com o objetivo de promover a formação de filmes com menos descontinuidades. Neste trabalho a deposição eletroassistida foi comparada com a técnica convencional de imersão, bem como com a cromatização hexavalente. O precursor utilizado neste trabalho foi o ortossilicato de tetraetila (TEOS), um silano não funcionalizado. A comparação entre os pré-tratamentos foi realizada através de ensaios de corrosão acelerada em névoa salina, medida de aderência de tinta, espectroscopia de impedância eletroquímica e espectroscopia de energia dispersiva. Os resultados indicam que a deposição eletroassistida em potenciais catódicos promoveu maior cobertura do substrato.
Palavras-chave
Abstract
The standard method for the production of organosilane films by dip-coating may lead to non-homogeneous pretreatment layers, weakening its barrier protection against corrosion and paint adhesion. Therefore, the electro-assisted deposition technique, based on promoting water electrolysis and the consequent favoring of condensation reactions of the organosilane, is studied with the aim of promoting the formation of less discontinuous coatings. In this work the electro-assisted deposition was compared to the standard dip-coating method and to hexavalent chromate conversion coating. The precursor used in this work was tetraethyl orthosilicate (TEOS), a non-functional silane. The comparison between the pretreatments was carried out by salt spray tests, paint adhesion measurement, electrochemical impedance spectroscopy and energy dispersive spectroscopy. The results indicate that the electro-assisted deposition in cathodic potentials promoted higher coverage of the substrate.
Keywords
Referências
1 Vargel C. Corrosion of aluminium. Amsterdam: Elsevier; 2004.
2 Joseph R. ABCs of painting on aluminum. Metal Finishing. 2008;6(2):39-44.
3 Ita AO. Paint pretreatments for aluminum. Metal Finishing. 1999;97(5):87-91.
4 Xue D, Van Ooij WJ. Corrosion performance improvement of hot-dipped galvanized (HDG) steels by electrodeposition of epoxy-resin-ester modified bis-[tri-ethoxy-silyl] ethane (BTSE) coatings. Progress in Organic Coatings. 2013;76(7-8):1095-1102.
5 Kalidhasan S, Santhana Krishna Kumar A, Rajesh V, Rajesh N. The journey traversed in the remediation of hexavalent chromium and the road ahead toward greener alternatives—a perspective. Coordination Chemistry Reviews. 2016;317:157-166.
6 Fedel M. Environmentally friendly hybrid coatings for corrosion protection: silane based pre-treatments and nanostructured waterborne coatings. Trento: University of Trento; 2009.
7 Costa JS, Agnoli RD, Ferreira JZ. Corrosion behavior of a conversion coating based on zirconium and colorants on galvanized steel by electrodeposition. Tecnologica em Metalurgia, Materiais e Mineração. 2015;12(2):167-175.
8 Pommiers S, Frayret J, Castetbon A, Potin-Gautier M. Alternative conversion coatings to chromate for the protection of magnesium alloys. Corrosion Science. 2014;84:135-146.
9 Zhang M, Mu S, Guan Q, Li W, Du J. A high anticorrosive chromium-free conversion coating prepared with an alkaline conversion bath on electroless Ni–P coating. Applied Surface Science. 2015;349:108-115.
10 Gan Y, Chen D, Kang Z. A highly anticorrosive chromium-free conversion coating prepared on electroless Ni–P coating. Surface and Coatings Technology. 2016;287:25-32.
11 Van Ooij WJ, Zhua D, Stacy M, Seth A, Mugada T, Gandhia P, et al. Corrosion protection properties of organofunctional silanes—an overview. Tsinghua Science and Technology. 2005;10(6):639-664.
12 Plueddemann EP. Principles of interfacial coupling in fibre-reinforced plastics. International Journal of Adhesion and Adhesives. 1981;1(6):305-310.
13 Iribarren-Mateos JI, Buj-Corral I, Vivancos-Calvet J, Alemán C, Iribarren JI, Armelin E. Silane and epoxy coatings: a bilayer system to protect AA2024 alloy. Progress in Organic Coatings. 2015;81:47-57.
14 Zheludkevich ML, Salvado IM, Ferreira MGS. Sol–gel coatings for corrosion protection of metals. Journal of Materials Chemistry. 2005;15(48):5099.
15 Díaz-Benito B, Velasco F, Pantoja M. Mechanical properties of polyester films painted after silanization of 6063 aluminium alloy with different pretreatment conditions. Progress in Organic Coatings. 2011;70(4):287-292.
16 Gandhi JS. Electrodeposition of organofunctional silanes for improved corrosion protection of metals. Cincinnati: University of Cincinnati; 2004.
17 Shacham R, Avnir D, Mandler D. Electrodeposition of methylated sol-gel films on conducting surfaces. Advanced Materials. 1999;11(5):384-388.
18 Hashem KME. Study of TEOS and TPOS anticorrosion coatings developed at different ranges of pyrolysis temperatures. Applied Surface Science. 2003;217(1-4):302-313.
19 Sakai RT, Cruz FMDL, Melo HG, Benedetti AV, Santilli CV, Suegama PH. Electrochemical study of TEOS, TEOS/ MPTS, MPTS/MMA and TEOS/MPTS/MMA films on tin coated steel in 3.5% NaCl solution. Progress in Organic Coatings. 2012;74(2):288-301.
20 Yan H, Yuanhao W, Hongxing Y. TEOS/silane coupling agent composed double layers structure: A novel superhydrophilic coating with controllable water contact angle value. Applied Energy. 2015
21 Hu J-M, Liu L, Zhang J-Q, Cao C-N. Effects of electrodeposition potential on the corrosion properties of bis-1,2- [triethoxysilyl] ethane films on aluminum alloy. Electrochimica Acta. 2006;51(19):3944-3949.
22 Hu J-M, Liu L, Zhang J-Q, Cao C-N. Electrodeposition of silane films on aluminum alloys for corrosion protection. Progress in Organic Coatings. 2007;58(4):265-271.
23 Li M, Yang Y-Q, Liu L, Hu J-M, Zhang J-Q. Electro-assisted preparation of dodecyltrimethoxysilane/TiO2 composite films for corrosion protection of AA2024-T3 (aluminum alloy). Electrochimica Acta. 2010;55(8):3008-3014.
Facebook
Google+
Twitter
LinkedIn
Mendeley
StumbleUpon
CiteULike
Reddit
Email