Modeling of the Inhibition-Mechanism Triggered by ‘Smartly’ Sensed Interfacial Stress Corrosion and Cracking

We present a simulation based study, by combining several models involving multiple time scales and physical processes, which govern the interfacial stress corrosion cracking (SCC) in grain boundaries, layered composites or bi-materials, and the mechanisms of inhibition using ‘smart’ agents. The inhibiting agents described herein, automatically sense the initiation of damage, migrate to the sites and delay the corrosion kinetics involved in the process. The phenomenon of SCC is simulated using the lattice spring model (for the mechanical stresses), coupled with a finite difference model of diffusing species, causing the dissolution of the interfacial bonds. The dissolution is expressed through a kinetic rate equation, which is solved stochastically using the kinetic Monte Carlo (kMC) to explore the fine selectivity of the evolution. Two alternative sensing mechanisms are employed, along the lines of the previous investigators; (a) the interactions among the inhibitor and the species and (b) the interaction of the inhibitors with the catalyst released under the action of the enhanced stress around the propagating crack front. Alternative forms of an empirically defined potential are used to model the chemical potential differences responsible for the driving force of migration. The inhibitor which migrates to the crack front initiates counter-dissolution kinetics (dealt with the kMC) to enforce the inhibition. The inhibition is quantified in terms of the time demand of these two competing kinetics (dissolution-inhibition). The robustness of the migration-inhibition is qualitatively inferred with respect to the random allocations of inhibitors in the domain.