Characterization of Oxide Layers on Alumina-Forming Alloy by Electrochemical-Impedance Spectroscopy.
Mentor 1
Benjamin Church
Location
Union Wisconsin Room
Start Date
5-4-2019 1:30 PM
End Date
5-4-2019 3:30 PM
Description
Stainless steel alloys are normally resistant to corrosion because of its chromium oxide (chromia) surface layer. Because chromia-forming stainless steel corrodes in the presence of extreme water vapor, carbon, and sulfur at high temperatures, interest has grown in a stainless steel alloyed with a small amount of aluminum. Instead of a chromia layer, a layer of aluminum oxide (alumina) can be formed on the surface. Alumina is superior in corrosion resistance because of its ability to inhibit the chemicals that chromia cannot impede. In this, there is no simple method to measure the corrosion resistance of an alumina-forming alloy (AFA). Electrochemical impedance spectroscopy (EIS) is seen as test that is relatively short, accurate, and inexpensive. To properly quantify the corrosion resistance of an AFA through EIS, a set of parameters are needed such as; the open circuit potential, perturbation amplitude, frequency, current, bandwidth, and several other adjustments. Parameters were tested in reference to a baseline stainless steel trial. Starting with this baseline, every parameter was modified and documented to see the effects of the changes on the results. The EIS trials were analyzed in different environments to see if errors in the results arose from sensitivity to its surroundings or testing framework. Bode plots were formed from the data and modeled to fit an equivalent circuit. This equivalent circuit is chosen as a theoretical model that can best represent the way in which the metal corrodes. Analysis is not complete and requires further parameter development.
Characterization of Oxide Layers on Alumina-Forming Alloy by Electrochemical-Impedance Spectroscopy.
Union Wisconsin Room
Stainless steel alloys are normally resistant to corrosion because of its chromium oxide (chromia) surface layer. Because chromia-forming stainless steel corrodes in the presence of extreme water vapor, carbon, and sulfur at high temperatures, interest has grown in a stainless steel alloyed with a small amount of aluminum. Instead of a chromia layer, a layer of aluminum oxide (alumina) can be formed on the surface. Alumina is superior in corrosion resistance because of its ability to inhibit the chemicals that chromia cannot impede. In this, there is no simple method to measure the corrosion resistance of an alumina-forming alloy (AFA). Electrochemical impedance spectroscopy (EIS) is seen as test that is relatively short, accurate, and inexpensive. To properly quantify the corrosion resistance of an AFA through EIS, a set of parameters are needed such as; the open circuit potential, perturbation amplitude, frequency, current, bandwidth, and several other adjustments. Parameters were tested in reference to a baseline stainless steel trial. Starting with this baseline, every parameter was modified and documented to see the effects of the changes on the results. The EIS trials were analyzed in different environments to see if errors in the results arose from sensitivity to its surroundings or testing framework. Bode plots were formed from the data and modeled to fit an equivalent circuit. This equivalent circuit is chosen as a theoretical model that can best represent the way in which the metal corrodes. Analysis is not complete and requires further parameter development.
