| About this Abstract |
| Meeting |
2021 TMS Annual Meeting & Exhibition
|
| Symposium
|
Coatings and Surface Engineering for Environmental Protection III
|
| Presentation Title |
Electronic Structure Mechanisms to Explain the Onset of Cl-induced Localised Corrosion in Al2O3 |
| Author(s) |
Aditya Sundar, Ganlin Chen, Liang Qi |
| On-Site Speaker (Planned) |
Aditya Sundar |
| Abstract Scope |
We investigate the fundamental electronic mechanisms driving Cl-induced localized pitting corrosion on α-Al2O3 surfaces. In the context of the point defect model, we model the adsorption thermodynamics of molecular HCl and Cl species substitutionally adsorbed on saturated α-Al2O3 surfaces, which have different local chemistries compared to the bulk crystal structure. Structural relaxations and room-temperature ab initio molecular dynamics simulations show that the adsorption energy of Cl is dependent on the local change in the anion electronic structures. By combined Bader charge, bond valence and orbital hybridization analyses, substitutional adsorptions of Cl are shown to be favorable at under-coordinated OH sites. The creation of Al-Cl bonds at these sites shifts the occupied electronic states to lower energies. Finally, we propose mechanisms to inhibit Cl adsorption by introducing alloying elements and stabilizing the electronic structure of the OH molecule at vulnerable sites. |
| Proceedings Inclusion? |
Planned: |