Inhibition of corrosion of Al and aluminium alloys in basic solutions

Abstract

<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">The technological importance and wide range of application of aluminium and its alloys have led to an extensive investigation on these materials. The corrosion behaviour of AI, AI-6061 and Al-Cu in basic aqueous solutions and the effect of three corrosion inhibitors were studied by EIS and polarization techniques. X-ray photoelectron spectroscopic (XPS) investigation of these materials revealed the presence of Cu in the AI-Cu alloy surface just below the surface of a thin film of hydrated aluminium oxide. EIS studies indicated the effectiveness of dichromate and molybdate in inhibiting corrosion of aluminium and its alloys. XPS studies of these materials after immersion of each in basic solutions containing separately 0.01 <i><span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:arial;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">M </span></i><span style="font-size:11.0pt; line-height:115%;font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;="" mso-fareast-font-family:"times="" new="" roman";mso-fareast-theme-font:minor-fareast;="" mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">dichromate, molybdate and sulphate ions respectively did not show the presence of chromium, molybdenum or sulphur on the surface film of these metals. SEM investigation of the electrode surface before and after immersion in the basic solution showed that the corrosion process is occurring in the flawed regions of the metal surface.</span></span>