Abstract

It has been known for at least a century that chloride has a major effect on corrosion, often increasing the rate of attack by an order of magnitude or more. This has serious consequences, not just for corrosion in sea water but also within humans; they have similar chloride ion levels. The literature is full of conflicting models each developed with particular approaches focusing on one aspect of the problem, rarely looking at the larger picture. The focus of this talk will be to show that the different conflicting models are not in fact conflicting. Density functional theory calculations show that chloride plays a critical role in disrupting the hydrogen bonding networks at oxide surfaces by replacing chemisorbed hydroxide. This leads to a reduction in the surface free energy which promotes morphological instabilities, these later conclusions being supported by transmission electron microscopy and atom probe tomography results.