Using Pulsed Phase Thermography to Detect Corrosion Under Paint and Coatings

http://onlineli...005918/abstract

A. Schönberger,, S. Virtanen, V. Giese, H. Schröttner, C. Spießberger

Wiley Online Library

Organic coatings in the automobile industry have to resist corrosion and
mechanical damage from stone chipping. Currently, no tool is established in
industrial non-destructive applications for analyzing the damage of stone-
impacts and the following corrosion after accelerated corrosion tests.
Measurement methods such as the scanning Kelvin probe can analyze the
corrosion progress in a detailed manner, but with a long measurement time.

The pulsed phase thermography (PPT) is a non-destructive tool to analyze
inhomogeneities and defects in materials, with a huge field of applications
existing. The present work shows advances in using the PPT to detect
propagation of corrosion under coatings. Physical principles of the mechanism
of the corrosion detection under coatings are described.

Results of measurements of organic coatings on carbon steel as well as of
organic coated galvanized steel show the corrosion propagation. Influencing
factors to the measurement such as the thickness of the coatings are
investigated, but no significant effect on the quality of the analysis was found.

The corrosion progress can be monitored by the PPT fast and reliably. The
achieved results correlate with the theoretical basis and the test results after
surface characterization and destructive analysis of samples.

Read the full article at Wiley Online Library:
http://onlinelibrary.wiley.com/doi/10.1002/maco.201005918/abstract