Sodium Benzoate as corrosion inhibitor for Aluminum Alloy AA 7618 in tropical seawater

Abstract

Corrosion is chemically induced damage to a material that results in deterioration of the material and its properties. Ships, marinas, pipelines, offshore structures, desalination plants, and heat exchangers are some examples of systems that experienced marine corrosion. Aluminum alloy is commonly used in marine applications. The use of inhibitors is one of the practical methods for protection against corrosion. Sodium benzoate has found considerable application as a corrosion inhibitor in low concentrations. The aim of this study is to analyze corrosion behavior of Aluminum alloy AA 7618 towards tropical seawater with the presence of sodium benzoate as corrosion inhibitor aimed to use in industrial applications. Immersion test and electrochemical test were conducted to measure the corrosion. The immersion period for the Aluminum alloy was 60 days. Seawater sample was collected from South China Sea along Universiti Malaysia Terengganu. This study reports the results of weight loss (%), inhibition efficiency (%), corrosion rate (mm/year), corrosion current densities (icorr), corrosion potential (Ecorr), polarization resistance,(Rp) and capacitance (CPE). The results showed that addition of sodium benzoate acted as inhibitor and minimize the corrosion of the aluminum alloy in seawater. The inhibition efficiency increases with the increase of immersion time. Electrochemical studies showed that there was a significant increase in overall resistance after addition of sodium benzoate. Inhibition efficiency is increased from 50% to 97% during the immersion period and increases with the immersion time. The result obtained lead to the conclusion that sodium benzoate is suitable to use as a corrosion inhibitor of Aluminum alloy AA 7618 in seawater.