Bonding and corrosion protection mechanisms of γ-APS and BTSE silane films on aluminum substrates
- 1 January 2003
- journal article
- Published by Taylor & Francis Ltd in Journal of Adhesion Science and Technology
- Vol. 17 (16), 2191-2221
- https://doi.org/10.1163/156856103772150788
Abstract
Films of γ-aminopropyltriethoxysilane (γ-APS), 1,2-bis[triethoxysilyl] ethane (BTSE) and their mixtures adsorbed onto pure aluminum from aqueous solutions were characterized by means of ellipsometry, infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS). It was found that after hydrolysis in water the silanes were readily adsorbed onto aluminum oxide surfaces initially forming hydrogen bonds. Upon curing, such bonds are replaced by metallosiloxane bonds, Si - O - Al. The remaining silanol groups in the film condense and form Si - O - Si bonds. As the Si - O - Al bonds are known to hydrolyze, the corrosion protection is related to the hydrophobicity of the siloxane films formed on the metal substrate. BTSE films are acidic as they contain free silanol groups, therefore these are compatible with some paints but not with others. Electrochemical impedance spectroscopy (EIS) results, salt spray test results and filiform corrosion test results showed that some silane treatments, such as two-step γ-APS/BTSE and BTSE only, provided better corrosion protection on aluminum substrates as compared with a chromate treatment. Mechanisms of adhesion and corrosion protection of these silane films on aluminum substrates are proposed.Keywords
This publication has 24 references indexed in Scilit:
- Characterization of films of organofunctional silanes by ToF-SIMS. Part II. Films of γ-APS, AEAPS and FPS on cold-rolled steel and cold-rolled zinc substratesSurface and Interface Analysis, 1993
- Silanes as the interphase in adhesive bondsJournal of Adhesion Science and Technology, 1992
- Silane Coupling AgentsPublished by Springer Science and Business Media LLC ,1991
- Organosilanes as adhesion promotersJournal of Adhesion Science and Technology, 1991
- Reminiscing on silane coupling agentsJournal of Adhesion Science and Technology, 1991
- Methods for improving the performance of silane coupling agentsJournal of Adhesion Science and Technology, 1991
- Infrared and X-ray photoelectron spectroscopy of aminophenyltrimethoxysilane films on metalsJournal of Adhesion Science and Technology, 1990
- Effect of substrates on the structure of polymer interphasesJournal of Colloid and Interface Science, 1988
- Silane Coupling Agents as Adhesion Promoters for Aerospace Structural Film AdhesivesThe Journal of Adhesion, 1987
- Hydrothermal Stability of Aluminum/Epoxy Adhesive BondsThe Journal of Adhesion, 1987