(5bi) Materials Engineering: Applications to Biomedical Implants and Magnesium Corrosion

Post-Doctoral Advisor: Dr. Mark F. Horstemeyer ? Center for Advanced Vehicular Systems (CAVS), Mississippi State University

Corrosive effects lead to the destruction and failure of many different materials in many different situations, including implants placed in the human body and metal used in engine cradles. One thing that all of these materials have in common is a necessity to engineer a material that can withstand these corrosive effects. My graduate and post-doctoral research has provided me with opportunities to examine methods to prevent corrosion in two different manners. In addition to exploring corrosion using two different methodologies, I have also had the opportunity to collaborate with other researchers, mentor graduate students, teach two different classes, and write proposals based on my research.

My initial work as a graduate student allowed me the chance to work on a way to improve the strength of adhesion of a coating on titanium to prevent corrosion caused by the human body and improve osseointegration. We began by chemically analyzing the surface of titanium as the coating was built in a three-step process, involving aminopropyltriethoxysilane, or a two-step process, involving triethoxsilylbutyraldehyde. We demonstrated that the silanes were unchanged and bound to the titanium surface when toluene was used as the solvent. Following the chemical analysis, mechanical testing was performed, which demonstrated that the films were strongly bound to the titanium surface. However, as expected, the toluene used to deposit the silanes resulted in slow growth of bone cells, making toluene an inappropriate solvent for use in biomedical coatings. My graduate work, and my post-doctoral work, in this area provided me with one method to prevent corrosion, which was to creating a coating that protects the metal beneath it.

A second way to prevent corrosion is what I am currently working on as a post-doctoral researcher in the Center for Advanced Vehicular Systems (CAVS). In order to improve a material, one must understand how it corrodes. We are currently working to determine the corrosion of two types of magnesium and how the application method of a NaCl aqueous solution affects corrosion. Pitting is the initial mechanism of corrosion and can ultimately lead to failure of material in which pitting occurs. Understanding how pit characteristics, such as depth, area, volume, and number density, change due to exposure ultimately will allow us to model this behavior. By modeling corrosive effects, the numerous magnesium alloys currently in production can be analyzed to determine which is most resistive to salt corrosion, allowing the lightweight material to be used in the automotive industry. This post-doctoral work has introduced me to a second method to prevent corrosion, which is to develop a material that can withstand corrosive effects by adding elements to improve the alloy.

I have had the opportunity to collaborate with many different people, departments, and universities, as both a graduate student and as a post-doctoral researcher. As the laboratory manager of the XPS equipment, I ran and analyzed samples for professors in Chemical Engineering, Plant and Soil Sciences, and Electrical and Computer Engineering. I also had the opportunity to work with people from the University of Texas Health Science Center and Georgia Tech. Because of my experience working with professors and other departments, I believe that I can develop strong collaborations between myself and other professors, including those in Mechanical Engineering, Biology, and Biological Engineering.

As a graduate student, I had the opportunity to assist with several classes and teach two classes by myself. The first class I taught was an entirely new laboratory for an established class, focusing on process design simulation. As part of my responsibilities, I created all of the materials needed, including the syllabus, Powerpoint presentations covering individual unit operations, homework, and a final project combining the individual unit operations into a working flowsheet. I also was responsible for grading both the homeworks and the final projects. I taught this class for the Fall and Spring semesters and was evaluated by the students, receiving 4.7/5.0 for both semesters. I also taught Unit Operations Laboratory I and II in the Spring semester. I was responsible for teaching the class, including assigning the groups to the experiments each week, for grading the laboratory reports, and for assigning final grades. As with the class I developed, I was evaluated by the students, receiving a 4.5/5.0 average.

As an assistant professor, I plan to continue collaborating with professors in both my research area, biomedical implants and biomaterials, and in other research areas and departments. I truly enjoy teaching and look forward to teaching both established undergraduate and graduate classes and classes I create based on my research interests.