Numerical Simulation of Micro-Galvanic Corrosion in Al Alloys: Effect of Geometric Factors

作者：Yin, Litao; Jin, Ying^*; Leygraf, Christofer; Birbilis, Nick; Pan, Jinshan^*

来源：Journal of the Electrochemical Society, 2017, 164(2): C75-C84.

DOI：10.1149/2.1221702jes

• COOPERATIVE STOCHASTIC-BEHAVIOR
• CATHODICALLY PROTECTED STEEL
• LASER-SCANNING MICROSCOPY
• ATOMIC-FORCE MICROSCOPY
• LOCALIZED CORROSION
• ALUMINUM-ALLOYS
• IN-SITU
• PITTING CORROSION
• CALCAREOUS DEPOSITS
• CREVICE CORROSION

A finite element model for simulating the propagation of intermetallic particle driven micro-galvanic corrosion in an Al-matrix model system is presented. The model revealed dynamic changes related to localized corrosion, including the moving dissolution boundary, the deposition of reaction products (Al(OH)(3)), and their blocking effect. Modelling was focused on the effects of key geometric parameters, including the radius of cathodic particle (range 0.5 to 4 mu m) and the width of an assumed anodic ring surrounding the particle (range 0.1 to 2 mu m). Simulations revealed the dynamic flow of molecular and ionic species, along with influence of geometrical constraints. For ring widths below 0.5 mu m, deposition of Al(OH)(3) inside the dissolving volume was inhibited due to limited transport of OH- and O-2 into a constrained volume - resulting in local acidification. An increase in cathodic particle radius at given ring width resulted in a greater dissolution by providing a larger cathodic area for O-2 reduction, quantifying the effect of cathode/anode ratio. The model was also developed to include two cathodic particles to explore any interaction. The present study reveals a physicochemical model that contributes toward a framework for multi-process localized corrosion systems, which can be further adapted to commercial alloy systems.

• 出版日期2017
• 单位北京科技大学