System Design and Operation

Sulfide-Induced Corrosion Research

Led by Vivian Merk, Ph.D.
Affiliated Home Campus: Boca Raton
Affiliated Department: Ocean and Mechanical Engineering and Chemistry and Biochemistry
REU Scholar: Charu Vijay
REU Scholar Home Institution: Tufts University

PROJECT

This project details the level and detail of corrosion on steel with the extension of its use on marine renewable energy. Corrosion presents itself as a topic of interest because of the length of time and harsh conditions in which ocean current turbines and other offshore machines operate. The set up for this project involved two types of steel, mild and marine, at two different Na2S concentrations, 0.005 M and 0.01 M. Steel squares were submerged in these solutions, which included 3.5% NaCl in order to mimic ocean conditions.

Through this project, different microscopy techniques, including light microscopy, Scanning Electron Microscopy, Raman Microscopy, and Atomic Force Microscopy, have led to the discovery of various minerals and formations. Lepidocrocite, haematite, goethite, maghemite, and pyrrhotite have been identified through utilizing a Raman microscope at 100x magnification in air with minimal laser power to avoid transformations. In addition, the atomic force microscope and scanning electron microscope have allowed the confirmation of a rocky and jagged surface, as well as several cubic structures. Circular pitting was found throughout every sample and the coloration transitioned from reddish-orange to black due to the formation of iron oxides and iron sulfides. The most significant difference between the 0.005 M Na2S and 0.01 M Na2S samples of mild steel was the time it took for apparent corrosion to occur, which was surprisingly shorter at the lower Na2S concentration. Overall, the marine steel remained unchanged and uncorroded over the ten-week period and further examination would be useful to discover a corrosion timeline for a real-world application of marine renewable energy.

Click here to watch the student presentation.