abstract
Deep eutectic solvents have been widely acknowledged as ionic liquid analogues, since they share many characteristics and properties with ionic liquids. The two major application areas of deep eutectic solvents have been metal processing and synthesis media; however, plenty of other applications have already been reported and predicted for these liquids. Reline, an eutectic mixture of choline chloride and urea, is a well known representative of deep eutectic solvents. Despite their importance in the contemporary technologies, the knowledge about the corrosivity of deep eutectic solvents is remarkably scarce. This article reports the results on the corrosivity of reline towards two Al alloys, namely AA2024-T6 and AA6065-T6. To measure the corrosion rates and characterize the passive film on the alloys in reline, electrochemical impedance and inductively coupled plasma optical emission spectroscopy methods were used, and the corrosion product composition was analyzed by X-ray photoelectron spectroscopy. Surface morphology and Volta potential were imaged by scanning electron microscopy, atomic force microscopy and scanning Kelvin probe force microscopy. The corrosion tests show that the two alloys are extremely stable in reline, and the passive layer is formed in the first three hours of immersion in the corrosive media. There is no evidence that electrolyte species are incorporated into the Al oxide protective layer through chemical bonding. (C) 2020 Elsevier Ltd. All rights reserved.
keywords
DEEP EUTECTIC SOLVENTS; PITTING CORROSION; ALUMINUM-ALLOYS; METALS; EXTRACTION; IMPEDANCE; STABILITY; OXIDES; STEEL; MEDIA
subject category
Electrochemistry
authors
Bucko, M; Bastos, AC; Yasakau, KA; Ferreira, MGS; Bajat, JB
our authors
Kiryl Yasakau
Assistant Researcheracknowledgements
This research was financed by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Contract No. 451-03-68/2020-14/200135). The authors would like to acknowledge support for Serbia-Portugal bilateral project (337-00-0 0227/2019-09/80). ACB acknowledges FCT-Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. K.A. Yasakau thanks the Portuguese Foundation for Science and Technology (FCT) and Programa Operacional Capital Humano, comparticipado pelo Fundo Social Europeu e por fundos nacionais do MCTES for the financial support and Researcher grant (IF/01284/2015). Project CICECO - Aveiro Institute of Materials - UIBD/CTM/50011/2020 and UIBP/CTM/50011/2020, financed by national funds through the FCT/MCTES, and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement is also acknowledged.