Multi-State Reliability Modeling and Assessment for Corrosion of Organic Coating-Substrate Structure

Abstract The organic coating-substrate structure suffers from corrosion reaction between the substrate material and water molecules during the storage stage. Multiphysics simulation is a promising tool for corrosion modeling and assessing the reliability of the organic coating-substrate structure. In this paper, a multistate modeling method is proposed toward the reliability modeling and assessment. First, to analyze the physicochemical process involved in the corrosion of organic coating-substrate structures, a multiphysics simulation method is developed. Then, the degradation performance of the organic coating-substrate structure is discretized into several states, and a Markov model is utilized to model the degradation process of the structure. The transition intensities of the Markov model are estimated by using the multiphysics simulation data. In the proposed method, the multiphysics simulation method can incorporate the diffusion equation and the kinetic equation of the corrosion, allowing for the simulation of water molecule diffusion within the organic coating and the coupling simulation of the metal corrosion process. Subsequently, the reliability of the organic coating-substrate structure is analyzed under varying temperatures, humidity levels, and protective material parameters. The result shows that higher ambient temperatures and relative humidity levels contribute to an accelerated corrosion rate of the substrate, and the reliability decreases.