Date Thesis Awarded

4-2016

Document Type

Honors Thesis

Degree Name

Bachelors of Science (BS)

Department

Physics

Advisor

William Cooke

Committee Member

Henry Krakauer

Committee Member

Hannes Schniepp

Abstract

Molten salt can be used to transfer and store energy, but presents challenges in terms of corrosion. In this research, we investigate the early stages of corrosion on stainless steel exposed to molten nitrate salts. Specifically, we are interested in the initial attack on grains and grain boundaries, including the effects of internal stress and/or a weakened passivation layer. We have developed procedures for exposing stainless steel coupons to a mixture of molten sodium nitrate and potassium nitrate at 565$\celsius$. Following exposure to molten salt, samples are analyzed using field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX). We have captured a series of images showing the nanoscale growth of corrosion on 316SS from zero to 30 minutes of exposure. Based on our EDX data, we hypothesize that corrosion on plateau areas at these short time scales is proportional to $(1-e^{t/\tau})$ for a characteristic time $\tau$. We conclude that EDX appears to be a suitable method for estimating the level of corrosion on stainless steel exposed to molten salt.

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Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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