Sol-Gel Corrosion Sensors

Abstract

Internal corrosion on the steel inside structures can make the structures dangerous and potentially cause accidents or collapses, such as the collapse of the I-35 Bridge in Minneapolis, MN. In order to avoid such problems, engineers need to find a way to gather information about the health of the structure. Strain sensors can be attached to the outside of structures to detect excessive amounts of load bearing on a particular support. Unfortunately, strain sensors only give information about the outside material. To solve this problem, engineers are developing ways to "see" inside structures with corrosion sensors. Sol-gel is an amorphous, mechanically stable, porous material that has been found to change its conductivity as a function of the amount of chloride ions it absorbs. When steel corrodes, it gives off an abundance of chloride ions. By absorbing these ions, corrosion sensors can detect when the corrosion has reached an unsafe level by being adhered to the steel beams embedded into the concrete of a structure. The goals of this project were to design electrodes for the sensors of different geometries to determine the optimal shape, to observe and improve the stability of the sol-gel coating, and to use different methods of coating to obtain a more uniform coating.