Characterization of Oxide Layers on Alumina-Forming Alloy by Electrochemical-Impedance Spectroscopy Ismael Coello (Undergraduate), Benjamin Church (Advisor), Ph.D Department of Materials Science and Engineering

Table of Contents Introduction Cell Characteristics Equivalent Circuit Bode Plot Results Conclusion Acknowledgements

Introduction Alumina-Forming Alloy (AFA) vs regular stainless steel Advantages of EIS Cost effective and simplicity Accuracy of results Quantifiable data Parameter development needed

Cell Characteristics Three-electrode electrochemical cell Working: AFA Reference: Saturated Calomel Counter: Platinum Mesh Sodium Sulfate Electrolyte Purged for one hour Potentiostat EC-Lab software

Equivalent Circuit Actual Theoretical

Bode Plot Actual vs Theoretical Diagnosis of problem

Results “Dummy” Cell Noise in Data Parameters Extended Cables Reference electrode Noise in Data Surroundings Faraday Cage Parameters

Conclusion Research is ongoing. Similarities between actual and theoretical impedance suggests that noise in data is due to reference electrode. Reference electrode has been cleaned and changed of its KCl solution, to not noticeable change. Next steps would involve obtaining a new electrode and analyze its effectiveness. If test is successful, a test/equation to validify data would be necessary.

Acknowledgements Dr. Benjamin Church for his guidance Support for Undergraduate Research Fellows Lizeth Ortiz for SEM pictures of AFA Alloy Rob Roberts for parameter development help Literature used as reference, J. Pan, C. Leygraf, R.F.A. Jargelius-Pettersson, J. Linden Oxid. Met., 50 (1998)