abstract
In this work, a hybrid epoxy-silane coating was developed for corrosion protection of magnesium alloy AZ31. The average thickness of the film produced by dip-coating procedure was 14 mu m. The adhesion strength of the epoxy-silane coating to the Mg substrate was evaluated by pull-off tests and was found to be higher than 16 MPa both in dry and wet conditions. The hybrid epoxy-silane coating showed high corrosion resistance both when intact and when punched through by a needle. The low frequency impedance of intact coating was higher than 1 G Omega cm(2) after one month of immersion in 3.5% NaCl solution. Both, artificially induced defects and corrosion sites that appeared on the metal surface did not propagate. Their passivation behavior, that we call fault-tolerance, was observed by EIS, SVET-SIET and SEM-EDS. It was ascribed to the good adhesion, high coating integrity and corrosion inhibiting effect provided by diethylenetriamine used as epoxy hardener. (C) 2014 Elsevier B.V. All rights reserved.
keywords
SOL-GEL COATINGS; ORGANIC COATINGS; IONIC CURRENTS; SILICA HYBRIDS; PH
subject category
Chemistry; Materials Science
authors
Lamaka, SV; Xue, HS; Meis, NNAH; Esteves, ACC; Ferreira, MGS
our authors
Mário Guerreiro Silva Ferreira
Retired ProfessorProjects
Fault-tolerant anticorrosion coatings for magnesium alloys (PTDC/CTM-MET/112831/2009)
1-D nanostructures obtained by electrodeposition from ionic liquids (PTDC/CTM-NAN/113570/2009)
Enhancing Scanning Ion-Selective Electrode Technique - SISET (SISET)
acknowledgements
This work was supported by Portuguese Foundation for Science and Technology (FCT) (projects PTDC/CTM-MET/112831/2009, PTDC/CTM-NAN/113570/2009, PTDC/CTM-MET/113645/2009). The authors would like to acknowledge Airbus Group Innovations, Munich, for supplying the alloys. FP7 Marie Curie IRSES project SISET - Enhancing Scanning Ion-Selective Electrode Technique, FP7-PEOPLE-IRSES-GA-2010-269282 is acknowledged for the work related with the usage of simultaneous SVET-SIET.