Corrosion protection of steel cut‐edges by hot‐dip galvanized Al(Zn,Mg) coatings in 1 wt% NaCl: Part II. Numerical simulations

Abstract

In this paper a mechanistic model is elaborated to simulate the corrosion behavior of aluminum–zinc–magnesium coatings on steel. The model is based on the mass transport and reactions of the ions in the electrolyte (MITReM). The finite element method has been used, which allows to perform time‐dependent simulations with micrometer scale to study local corrosion effects. The formation of corrosion products and the prediction of electrolyte concentration distributions are compared for different metallic coating compositions. The spatial and temporal simulation of complex precipitates provides an additional tool to validate the model through corrosion product characterization. The simulation results are compared to experimental observations, presented in part I of this paper. The MITReM simulations are limited to the micro‐scale and therefore to small geometries. A link is made with the potential model which can be applied on macro‐scale objects. A qualitative agreement is found between the simulations at both scales and the experiments. Further quantification of this model would optimize the simulations for material design and for predictive maintenance.

Effect of a Fast Potential Change on the Early Stage of Zinc Passivation in a Saturated Calcium Hydroxide Solution

“…3, just seven of them were used for the sake of simplicity and are presented in Table 1. The rate constants, k f and k b , of chemical reactions were taken from the literature (Zhang and Muhammed, 2001;Ziegler and Johnson, 2001;Dolgikh et al, 2019). On the other hand, the following two electrochemical reactions were taken into account:…”

“…where n is the number of transferred electrons in each heterogeneous reaction and v is the stoichiometric coefficient TABLE 1 | Homogeneous reactions and kinetic constants (Dolgikh et al, 2019).…”

Finite Element Method for Thin Film Corrosion Modelling: Where We Advanced and Where We would like to Advance?

“…Rather, regions of the solution that were supersaturated with the corrosion products were predicted as depicted in Figure 1. Likewise, Dolgikh et al [15] predicted corrosion products in a hot-dip galvanized Al(Zn, Mg) coating system.…”

“…Rather, regions of the solution that were supersaturated with the corrosion products were predicted as depicted in Figure 1. Likewise, Dolgikh et al [15] predicted corrosion products in a hot-dip galvanized Al(Zn, Mg) coating system. One of the key issues to be addressed is the simulation of a dynamic layer of varying thickness and concentrations due to evaporation, which can be done by the NP approach.…”

“…Saeedikhani et al [11] considered that the surfaces of electrodes were covered by porous corrosion products, incorporating into their model the porosity values obtained by image analysis of corroded samples in the early stages of exposure [22]. In contrast, Dolgikh et al did not consider surface coverage by corrosion products in their model as they had not experimentally observed any blocking action by corrosion products [15,23]. Future thin film models are needed to be developed in a way that both predicts the locations of corrosion-products-blocked sites as well as their porosity, rather than having them as pre-existing parameters.…”