1. 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

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

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

4. 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

5. Equivalent Circuit
Actual
Theoretical

6. Bode Plot
Actual vs Theoretical
Diagnosis of problem

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

8. 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.

9. 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)