Dr. Warren’s research interests include:

Amime-Quinone Polymers – A New Class of Corrosion Resistant Coatings
In research performed at UA, a new polymer (AQ) has been shown to significantly improve the corrosion resistance of sub-micron sized Fe particles in an aggressive environment (pH 2). Similar improvement has also been found for Fe plates coated with the same polymer. These polymers show much promise for applications ranging from the magnetic tape industry to inhibitors or coatings for electronic materials and devices. The primary objectives of this research program are aimed at a fundamental understanding of the nature of the AQ polymer/metal interface and the mechanism by which the polymer improves corrosion resistance. Research in our laboratories has shown that although the AQ polymer coatings absorb water, they still inhibit the formation of a metal/electrolyte interface even after 150 days of exposure to 0.1 M NaCl. Our goal is to understand the nature of the bond between polymer and metal through two research thrusts. Interfacial properties are being examined by various techniques including typical DC electrochemical methods, AC impedance methods, FTIR, ESCA and Auger. This research is a collaborative effort with Drs. David Nikles and Shane Street in the Dept. of Chemistry.

Electrochemical Research in Permanent Magnets
Many Rare Earth-Transition Metal (RE-TM) materials can absorb significant quantities of hydrogen. In the case of LaNi5 the quantity of absorbed hydrogen is so large that it forms the basis for a new generation of electric (hydrogen storage) batteries with a significantly higher ratio of engergy capacity to weight than is currently available. Nd2Fe14B materials are becoming increasingly common in many small electric motors, generators, computer hard drives, etc. Unfortunately Nd2Fe14B materials exhibit relatively poor corrosion resistance. Previous research in our laboratories has shown that NdFeB materials also absorb hydrogen, though to a lesser extent. The composition of these materials is constantly evolving and small amounts of Ti, Co, Al, Dy, Ga, B, C, etc., can significantly affect the magnetic properties and the corrosion behavior. The processing steps that the material is subjected to also influences the structure and properties, including corrosion. Investigations in our laboratory have provided some of the few direct, electrochemical studies of the corrosion behavior of this class of materials. Results have shown that the addition of selected alloying elements can significantly improve corrosion resistance, and that the absorption of hydrogen is often synonymous with increased corrosion rates. Recent results have shown that TiC additions in conjunction with rapid solidification techniques can decrease corrosion rates by a factor of two or three. Similarly, die upset and hot pressed magnets show improved corrosion resistance compared with sintered magnets.