Paints and coatings monitored by laser-induced breakdown spectroscopy
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Two algorithms—peak picking and peaks correlation—have been compiled in a portable laser-induced breakdown spectroscopy (LIBS) system and used specifically for spectral fingerprinting of paints and coatings, which contain multiple ingredients and require several application steps. The LIBS technique starts with a laser shot on the specimen surface, detection of the emission of the elements present, and analysis of the sample compositions. The LIBS system has been successfully illustrated for the identification and analysis of coating substrates, surface pretreatments, and primer and topcoat paints obtained in the lab and at field sites. The results indicate that, despite the compositional complexity in organic metal finishing, the spectral fingerprint of paints and coatings can be effectively determined by the LIBS technique. The advantages of LIBS technique over other conventional methods, such as EDX, are that it is quasi-nondestructive (<100 μm of sample size), requires no sample preparation, is fast (within minutes), is user-friendly (for nontechnical personnel), and is capable of application both online and at the field sites.
KeywordsSurface analysis Laser spectral fingerprinting Pigments Quality control Correlation algorithms Chromate Phosphate Aluminum Coating-substrate interface Galvanized steel Alloy-coated steel
This work was supported partially by a research contract from Caterpillar, Inc. The authors would like to thank Mr. B. McCanne, Mr. David Chisari, and Mr. Chien-Chung Teng for their assistance in the CoatID software development.
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