Modeling Corrosion Behavior of Aluminum Nitride-Coated Steel in Oxygen-FreeAqueous Potassium Chloride

摘要

The purpose of this paper is to discuss a refined model for the corrosionbehavior of AIN-coated 1008 mild steel in oxygen-free 0.2 M KCI, using data from scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and pH measurements on test electrolyte. AIN coatings provide corrosion protection for steel by providing a physical barrier to H+ ion diffusion to the substrate steel and an electron transport barrier between the substrate and electrochemically active species in KCI electrolyte. Surface (external and internal) AIN reacts with water to form Alhydroxide, possibly AI(OH). This hydroxide covers surfaces (both external and internal) within 48 h after the coated steel is immersed in solution, causing a decrease in the dissolution rate of AIN by water and sealing internal surfaces. Sealed internal surfaces impede H+ ion diffusion to the steel substrate.