Determination of the potential use of ethylene glycol as a corrosion inhibitor in 3.5% NaCl

The majority of the metals used in industry are exposed to aqueous media. The thin liquid film layer developed on metals and their alloys in an aqueous environment causes oxidation by forming metal ions and metal compounds (metal oxides, hydroxides, salts) from their metallic states. This unwanted process is called corrosion. Due to corrosion, the physico-mechanical properties expected from metals and their alloys are weakened or disappear completely. This situation leads to serious technical problems and economic loss. In order to solve these problems and reduce economic losses when metal is subjected to a corrosive environment, there is a need for chemicals that reduce or prevent the rate of corrosion, i.e., corrosion inhibitors. This study investigated the corrosion mechanism of the AA7075 alloy in a 3.5 % NaCl solution and the effect of ethylene glycol as a corrosion inhibitor. Ethylene glycol was selected due to its light weight, low cost and properties of high electrical and thermal conductivity. Ethylene glycol is used as antifreeze in radiators to cool or keep vehicle engines at a constant temperature. It is widely employed as a preventative chemical added to water with which a plane is washed before take-off in order to keep the body of the aircraft from freezing and icing over. Tafel extrapolarization (TP) and dynamic electrochemical impedance spectroscopy (DEIS) were used to investigate the interaction of the AA7075 alloy, which is used in the aerospace sector and in radiator production, with ethylene glycol (10, 20, 30, 40 and 50 % by volume) in a 3.5 % NaCl solution. The electrochemical measurement data showed that the ethylene glycol molecules were physically adsorbed onto the AA7075 surface in accordance with the Langmuir adsorption isotherm. The SEM, EDAX and AFM analyses conducted after the electrochemical experiments demonstrated that the AA7075 alloy showed less corrosion as the amount of the inhibitor was increased.