Corrosion is a form of material deterioration process due to chemical interactions with surrounding environment. Metals must be isolated or protected to avoid corrosion. Metallic components of amphibious vehicles are exposed to aggressive conditions during their service lives. These components are coated with organic substances to isolate metal surface from corrosive species. Occasionally, protective layer on metallic components fails due to poor adhesion, chalking, peeling and delamination. Damaged areas on coated components may become exposed to seawater. Cathodic protection is an effective method to inhibit corrosion of metallic components of amphibious vehicles which are in direct contact with seawater.

Selected steel types and aluminum alloys [1], which are used in manufacturing the hulls of armored amphibious vehicles, were subjected to accelerated corrosion tests in synthetic seawater to collect data for simulation of cathodic protection. Typical Nyquist and Tafel plots are shown in Figure 1. COMSOL Multiphysics modeling software [2] was used to integrate electrochemical data obtained by both impedance spectroscopy and potentiostatic tests to simulate cathodic protection of the vehicle hulls under seawater. Potential and current density distributions in marine environment were evaluated to design the cathodic protection system that could impress the currents. The size, shape and locations of sacrificial anodes were optimized to enhance homogenous protection performance.

[1] National Research Council (U.S.). (2013). Materials for Lightweight Military Combat Vehicles: Report, Nabu Press

[2] COMSOL Multiphysics 5.1, Corrosion and Electrochemistry Modules