Optimization and characterisation of commercial water-based volatile corrosion inhibitor

Volatile corrosion inhibitor (VCI) provides protection for metal surfaces. VCI coating and molecules attach themselves to metal surfaces to form both a physical film when contacted and an invisible thin film for indirect contact through Vapour (only a few molecules thick), thus inhibiting metals atmospheric corrosion. Optimization and characterisation of commercial water-based volatile corrosion inhibitor VCI (Vapour-Phase-Protection, VAPPRO 837C diluted commercial solution from CORPPRO) was prepared to determine their characteristics and effectiveness against corrosion of carbon steel. The main scope of this work is to characterise the rheological and corrosion inhibition properties of the VAPPRO 837C with varying formulations and processing parameters (coating and drying times). Different tests were performed to determine the corrosion behavior of inhibitor. The application of VCI on the metal surface was done by dip-coating process. An Electrochemical Workstation from HCH Instruments has been used to evaluate the corrosion inhibition efficiency of the VCI and to determine the corrosion rate of the uncoated and coated samples. In addition, viscosity tests were carried out in order to determine the rheological properties of the formulation, as well as Freeze-Thaw resistance of water-borne coatings and pH tests were done. A FTIR spectrometer has been used to determine the functional groups present at a specific concentration. Results reveal that the most effective VCI film was obtained from a 0.25 CORPPRO (Concentrated VCI) (vol%) formulation using a coating time of 10 min and a drying time of 24 h. Therefore, 0.25 CORPPRO would be the optimum concentration to be used because it is able to achieve the highest corrosion inhibition efficiency with the optimum coating drying time.