Effects of Si addition on the corrosion susceptibility of aluminium alloys in different concentrations of NaOH, and NaCl solutions

This study examines the effect of silicon addition at 5%, 10%, and 15% by weight on the corrosion susceptibility of aluminium alloys in 0.5 M and 1.0 M sodium hydroxide (NaOH) solutions, as well as 0.5 M and 1.0 M sodium chloride (NaCl) solutions. The aluminium was moulded and furnished, and the alloys were exposed to these corrosive environments for durations ranging from 168 to 672 hours. The corrosion behaviour of the alloy samples was assessed by measuring the weight loss, from which the corrosion rate was calculated. The results showed that the normal corrosion rate profile was observed as the reinforcement phase increased, and the samples increased in weight. This indicates continuous passivation, particularly in the 10% Si alloy content resulted in a low corrosion rate of the alloy, which was significantly lower than the other concentrations, indicating superior resistance. Based on these findings, it is recommended to optimize the silicon concentration at 10% for enhanced corrosion resistance in alkaline and salty corrosive environments. These alloys, with corrosion rates ranging from 0.01 to 0.05, are well suited for aerospace, marine, automotive, and chemical processing plant applications where materials are exposed to corrosive conditions and require durability.