Assessment of salt and acid droplets evaporations on the corrosion mechanism of aluminum

Abstract

An approach for new experimental set up for monitoring the corrosion rate of aluminum along with the contact angle, droplet volume loss and droplet height of a single droplet of NaCl , NH<inf>4</inf>SO<inf>4</inf>, H<inf>2</inf>SO<inf>4</inf> and HNO<inf>3</inf> solutions placed gently on aluminum surface was suggested. Electrochemical impedance spectroscopy (EIS) technique was employed for monitoring the corrosion rate, while the contact angles, volume loss and droplet height changes were monitored using drop shape analyzer. The evaporation process for the droplets from aluminum surface is followed and characterized. The evaporation of droplet is highly dependent upon the reaction of salt and acid with exposed aluminum surface, which is important for monitoring the contact angle and droplet height. The constancy of the base diameter determines the evaporation mode of the droplet. The change in a contact angle shows a remarkable decrease with droplet holding time. The corrosion process of aluminum is mainly dependent upon droplet height. The volume losses increase, while the droplet height decreases as droplet holding timer progressed. A mechanism describing the corrosion process inside the droplet is suggested.