Detection of different chemical binders in coatings using hyperspectral imaging

Abstract

AbstractOrganic coatings protect metallic structures of significant commercial value. Regular inspections of coatings are required to ensure their integrity and, therefore, to verify their stated performance. However, for metallic structures located in harsh places, coating inspection can pose significant safety and logistical challenges. Near-infrared (NIR) spectroscopy is a rapid, nondestructive and relatively inexpensive analytical technique. It is currently employed to analyze different chemicals in fields like agriculture, food, and pharmaceuticals. Similarly, hyperspectral imaging (HSI) creates a spatial map of spectral information by measuring light reflected from a material. In this work, hyperspectral imaging in the NIR portion of the electromagnetic spectrum (NIR-HSI) is used to accurately distinguish between the chemically different binders employed in commercial organic coatings. In addition, k-means clustering is explored as a tool to provide diagnostic information about the spatial inhomogeneities in the chemical structure of an applied coating, which, if undetected, can lead to coating defects during service life. The results of this work suggest that the NIR-HSI could be used for remote inspections of organic coatings.