Investigation on Corrosion Protection applying organic–inorganic sol–gel coatings on AA2024-T3
Tutor / director / evaluatorArmelín Diggroc, Elaine Aparecida
Document typeBachelor thesis
Rights accessOpen Access
In order to prevent corrosion on aluminium and aluminium alloys, many surface treatments have been developed, such as silane films, which are environmentally compliant coatings. During this work we investigate corrosive behaviour of aluminum alloys AA2024 in a NaCl 0.05mol L-1 coated with MEMO/Bis-EGMP/TiB, during the Part A and TEOS/ATMP/GPTMS during the Part B. The aluminium alloy substrates were pre-threated before the coating deposition. The silane coatings were applied using sol-gel system. After silane curing process, all the substrates were covered with a commercial epoxy coating in order to provide the topcoat protection before the samples immersion in the aggressive solution for corrosion tests (NaCl 3.5%). Electrochemical techniques were applied during Part A in order to evaluate the corrosion protection of silane coating. Microscope and optical analysis was carried on during this work to evaluate the film surface homogeneity and the presence or absence of defects. The samples prepared were tested under accelerated corrosion environment, which showed that the samples prepared on Part A of the present study did not have good protection performance. On the other hand, samples prepared during Part B showed excellent behaviour and the silane coating prepared from TEOS/ATMP/GPTMS system protected the aluminium surface from the aggressive corrosion medium. Adherence of silane system and also the topcoat applied is essential to obtain a long time protection. Therefore, pull-off tests were performed to confirm the efficacy of the coating adherence.