Studies of Corrosion Inhibition Performance of Inorganic Inhibitors for Aluminum Alloy

In this study, the behavior of sodium silicate (Na2SiO3), manganese sulfate monohydrate (MnSO4<middle dot>H2O), and ammonium metavanadate (NH4VO3) as corrosion inhibitors for AA6061 aluminum alloy (Al) was investigated. The polarization resistance (Rp) of the Al substrate immersed in 0.1 M NaCl solution was found to be 13 k ohm<middle dot>cm2. In comparison, the Rp of the Al substrate immersed in 0.1 M NaCl in the presence of Na2SiO3, Na2SiO3/MnSO4<middle dot>H2O, and Na2SiO3/NH4VO3 inhibitors was found to be 100, 133, and 679 k ohm<middle dot>cm2, respectively. The best inhibition result was obtained when the mixture of the inhibitors was used with Rp of 722 k ohm<middle dot>cm2. The maximum percentage of the corroded area calculated from the scanning electron microscopy (SEM) images was found to be 5.7% for Al substrate immersed in 0.1 M NaCl, which decreased to 0.06% when the mixture of the inhibitors was used. The synergetic effects between the three inhibitors were studied, and the results illustrated that the combination of Na2SiO3, MnSO4<middle dot>H2O, and NH4VO3 provided the best corrosion inhibition properties for Al in aqueous NaCl environments.