Isatin thiosemicarbazone derivatives as inhibitors against corrosion of AA6060 aluminium alloy in acidic chloride medium: substituent effects

• Published in: Journal of materials research and technology Vol. 9; no. 5; pp. 11935 - 11947
• Main Authors: Yuan, Qingyun, Cheng, Run, Zou, Song, Ding, Cheng, Liu, Hongxia, Wang, Yujie, Yang, Di, Xiao, Xin, Jiang, Qiong, Tang, Ruiren, Chen, Jingwen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2020; Elsevier
• Subjects: Aluminium alloy; Corrosion inhibitor; Substituent effects; Surface adsorption; Surface analysis; Thiosemicarbazone derivative; Surface adsorption; Substituent effects; Aluminium alloy; Thiosemicarbazone derivative; Surface analysis; Corrosion inhibitor
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2020.08.012

Five isatin thiosemicarbazone derivatives bearing different substituents (R) at 5-position of the isatin moiety, ISA-R, being R = -H, -CH3, -F, -Cl and -NO2, were synthesized and fully characterized. The corrosion inhibition action of ISA-R on AA6060 aluminium alloy in acidic chloride medium was studied in relation to the substituent effects using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), electrochemical potentiodynamic polarization (PDP) and weight loss measurements. The results showed that the inhibition behaviors of ISA-R were strongly correlated with the substituent modifications. ISA-NO2 was found to possess the highest capability to increase the corrosion resistance of the alloy and ISA-Cl exhibited some inhibition efficacy, whereas the others have little action. ISA-H, ISA-F, ISA-Cl and ISA-NO2 acted as cathodic-type inhibitors, and ISA-CH3 as a mixed-type inhibitor primarily retarding the cathodic processes of the alloy in the corrosion solution. ISA-R can be adsorbed on the alloy surface as evidenced by the results of EDS and XPS. The π-electron density on the isatin ring of ISA-NO2 is more deficient over the other ISA-R, which facilitates the adsorption of ISA-NO2 and formation of a barrier film on the alloy surface, and accordingly enhances its anti-corrosive performance for the alloy.