In-situ corrosion monitoring in military vehicles

Military vehicles are at a constant threat from harsh operational conditions in terms of temperature variations, humidity and exposure to atmospheric or aggressive chemical environments. These conditions are responsible for structural and components’ failure due to various corrosion failure mechanisms. Protective coatings tend to prevent the effect of physical and chemical attack on substrates. However, in some circumstances this attack is promoted, rather than hindered, and this results in the failure of coatings. This thesis presents novel theoretical models for three modes of coating failures i.e. micro-cracks effects, blistering and edge delamination. These models can be used for the analysis of coating failure initiation and propagation, especially useful for coating life assessment. The models follow multidisciplinary approach coupling the concepts of thermodynamics, fracture mechanics and electrochemistry. Novel equations involving inter-related multidisciplinary parameters are developed for stress-assisted diffusion rate, crack driving force and corrosion current density. These novel equations can be used by the manufacturers to design durable systems and can also be utilised for prognostics. Simple criterions i.e. critical/threshold values are identified which exclude the possibility of widespread coating failure propagation. The developed models are based on comprehensive experimental studies, which are also used to validate the theoretical predictions. The fundamental property which often dictates the performance of a coating is its adhesion to the substrate. There are many experimental techniques to measure the adhesion and analytical …