Researchers at Southwest Research Institute developed an embedded sensor system that detects paint and nonmetallic coating degradation on metal structures before it's visible.
The sensor measures the electrical impedance between a metal surface and its paint. An array of pins penetrates the metal substrate from beneath. After electronics have made the measurement, radio-frequency telemetry beams the data back to report the status.
During testing, researchers evaluated a three-coat polyurethane, one-coat polyurethane, and one-coat enamel on carbon-steel and aluminum-alloy substrates. Besides seeing degradation, the sensor can also find defects in the form of surface contamination and coating damage, as well as monitor the corrosiveness of rinse water and test the effectiveness of corrosion inhibitors.
The sensor is currently monitoring coating degradation in aircraft. However, researchers say the technology could work in automobiles, trucks, and military vehicles, as well as large structures such as suspension bridges.