Non Destructive Evaluation of Urethane-Epoxy Coating Systems using the Scanning Kelvin Probe Technique

This program will develop a nondestructive evaluation technique for measuring and analyzing the degradation and reversion of urethane-epoxy coating systems using a scanning Kelvin probe to address the stated need for a nondestructive evaluation tool for aircraft outer mold line urethane and epoxy integrity assessment and to identify premature failures. The scanning Kelvin probe is a non-contact, non-destructive instrument designed to measure the surface work function difference between a scanning probe reference tip and sample surface, and can be directly correlated to the surface condition. In Phase I, Faraday and UDRI demonstrated the ability to differentiate between a polyurethane rain erosion coating and an epoxy primer coating system using the scanning Kelvin probe, differentiate between a degraded and non-degraded polyurethane coating, epoxy primer and polyurethane/epoxy primer stack up coating system under a high humidity, high temperature environment, and accelerate the transition toward a fieldable probe with preliminary design activities. In Phase II we will validate and deliver to the US Air Force a prototype field deployable scanning Kelvin probe system that successfully maps out the coating system integrity on a stack of representative outer mold line coating materials.