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German and Austrian researchers have developed a quick, simple, non-destructive detection technology to measure corrosion under coatings applied to steel and galvanized steel.
The technology arose in the automotive coatings sector, developed by a team of researchers from automobile manufacturer BMW, the University of Erlangen-Nuremberg (Germany), the Centre for Electron Microscopy Graz (Austria), and Edevis (Enhanced Defect Visualization), a German firm that uses infrared thermography in non-destructive testing and material characterization.
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A. Schönberger et al. / Corrosion Science |
| A new detection method based on Pulsed Phase Thermography clearly reveals corrosion under coatings on steel. Researchers have even been able to correlate different thermography signals with specific defects. |
The research has focused on the damage and ensuing corrosion caused by stone chipping of a painted automobile surface.
However, the team says, the technology is easily transferable to “a huge field” of potential applications.
Heat Imaging
The process involves a new method based on a process known as pulsed phase thermography (PPT), a non-destructive tool that has successfully been used to detect and analyze defects and inhomogeneities in various materials.
In this case, the technology has been adapted to detect the spread of corrosion under coatings.
In an article in the journal Corrosion Science, the researchers explain that the corrosion measurements are “based on the influence of individual barriers, which are created by defects, on the thermal heat flux. Defective and intact layer systems can be well distinguished, due to the clearly diverse return signals.”
The team even has been able to correlate different signals with specific defects.
In a separate article on the research in the journal Materials and Corrosion, the team notes that it has worked extensively with measurements of organic coatings on carbon steel and galvanized steel.
The bottom line: “The corrosion progress can be monitored by the PPT fast and reliably,” the team writes. Even coatings of various thicknesses had no significant effect on the quality of the analysis, they said.
New Option
The team calls the technology a first.
“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,” the researchers write. “Measurement methods such as the scanning Kelvin probe can analyze the corrosion progress in a detailed manner, but with a long measurement time.”
They add: “The achieved results correlate with the theoretical basis and the test results after surface characterization and destructive analysis of samples.”
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