Characterization of Ceramic Membranes Using Electrochemical Techniques
Dr. Darryl Butt
Electrochemical reactions involve an exchange of electric charge which may accompany a coupled chemical reaction. Corrosion, electroplating, and power from batteries or fuel cells are examples of processes driven by electrochemical reactions. Electrochemical tests can be used to monitor and/or control the current and potential of an electrode typically immersed in a liquid or other ionic conducting environment. The work presented here is focused on the characterization of ceramic membranes synthesized at BSU. Synthesis of the ceramic membranes included powder mixing, pressing, and sintering. Ceramics are inorganic, nonmetallic materials and most frequently consist of nitrides, oxides or carbides. Typically, ceramics are very hard, stiff and strong but also extremely brittle and susceptible to fracture. Although usually insulators, some ceramics have excellent ionic conduction properties that make them ideal for use as ion-selective or ion-exchange membranes in chemical filtering or solid electrolytes in fuel cells. In the current research a Na+ ceramic filter (synthesized at BSU) was sectioned, mounted, polished and characterized prior to electrochemical testing. During testing two different electrochemical cell configurations were used, depending on the type of experiment being conducted:
•A standard three-electrode cell to measure surface properties of the ceramic.
•A four electrode membrane cell to monitor sodium ion filtering rate and efficiency.
The rate of ion-exchange, stability in water, and conductivity of these membranes was evaluated by electrochemical (impedance and potentiometric) analysis on a PAR 263A Potentiostat/Galvanostat, assisted by a PE 5210 amplifier circuit. A Gamry Reference 600 Potentiostat was also used for certain ranges of voltage. The focus of the work performed to date has been characterization of ceramic membranes to generate data for optimization of the membrane properties. This poster is an overview of the process and equipment capabilities for materials characterization using standard and novel electrochemical techniques.