Development of Coating Thickness Instrument for Graphite/epoxy Composites

The ability to measure the thickness of paint on graphite/epoxy composite structures directly would be of benefit in the aerospace industry. The weight reduction would increase fuel mileage for the airline customer. An additional reason for reducing the thickness of paint on graphite/epoxy composites is not as obvious as the weight savings. A concern in the use of composite structures has been the effect of paint chipping after 2 to 3 years of service life. It has been postulated that the primary cause has been the application of surfacer or primer. The primer is less plastic than the top layer of paint and cracks form as the primer goes through temperature cycles. If the primer or surfacer is too thick, the crazing is more likely than with thinner applications of primer or surfacer.