Event Title

Characterization of Oxidation Layer of Alumina Forming Stainless Steels in Molten Salt Using Electrical Impedance Spectroscopy and Microscopy

Presenter Information

Miguel Jaimes

Mentor 1

Ben Church

Location

Union Wisconsin Room

Start Date

27-4-2018 1:00 PM

Description

One of the biggest challenges of concentrated solar power plants is the corrosion of the storage containers and pipes used to transport of molten salts which store the sun’s heat energy. Stainless steels that are currently used for this process form a chromium oxide layer that is not very resistant to hot corrosion, but new alumina forming steel alloys show very high resistance due to a protective Al-Cr rich oxide layer. Properties of this oxide layer such as thickness, surface structure/ composition, and resistivity are of interest in this study. This oxide layer can be analyzed with electrical impedance spectroscopy (EIS), a technique that models the oxide layer’s electric properties with a combination of resistors and capacitors. Composition and surface structure will be investigated through microscopy techniques such as confocal microscopy and scanning electron microscopy. An induction furnace will be used to melt a 60 wt% NaNO3 40 wt% KNO3 salt solution and when keeping at 390 degrees Celsius, samples of alumina forming steel will be tested against a graphite reference electrode inside the molten solution while connected to a potentiostat that records EIS data. All data will be analyzed to determine if and how the thickness and composition of the oxide layer affect the corrosive resistance of the steel. This study may be of value to research currently being done on alumina-forming austenitic steel alloys at UWM’s Materials Science and Engineering department if the results are deemed relevant.

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Apr 27th, 1:00 PM

Characterization of Oxidation Layer of Alumina Forming Stainless Steels in Molten Salt Using Electrical Impedance Spectroscopy and Microscopy

Union Wisconsin Room

One of the biggest challenges of concentrated solar power plants is the corrosion of the storage containers and pipes used to transport of molten salts which store the sun’s heat energy. Stainless steels that are currently used for this process form a chromium oxide layer that is not very resistant to hot corrosion, but new alumina forming steel alloys show very high resistance due to a protective Al-Cr rich oxide layer. Properties of this oxide layer such as thickness, surface structure/ composition, and resistivity are of interest in this study. This oxide layer can be analyzed with electrical impedance spectroscopy (EIS), a technique that models the oxide layer’s electric properties with a combination of resistors and capacitors. Composition and surface structure will be investigated through microscopy techniques such as confocal microscopy and scanning electron microscopy. An induction furnace will be used to melt a 60 wt% NaNO3 40 wt% KNO3 salt solution and when keeping at 390 degrees Celsius, samples of alumina forming steel will be tested against a graphite reference electrode inside the molten solution while connected to a potentiostat that records EIS data. All data will be analyzed to determine if and how the thickness and composition of the oxide layer affect the corrosive resistance of the steel. This study may be of value to research currently being done on alumina-forming austenitic steel alloys at UWM’s Materials Science and Engineering department if the results are deemed relevant.