An approach for fast and qualitative detection of thin coatings on non-woven fabric via laser-induced breakdown spectroscopy

Abstract

In modern textile industry, the application of thinnest functional coatings on fabrics has become state-of-the-art for realising daily used goods with defined surface properties. However, since woven fabrics or non-woven textiles feature complex and undefined surfaces, classical measurement of the thickness and thickness homogeneity via classical geometrical methods is a challenging task. Against this background, an alternative approach based on spectroscopic data was investigated in this work. For this purpose, polyester non-woven textiles and plane control samples were coated with silicon suboxide-like layers using a plasma coating process. The coating thickness was then detected indirectly by measuring the ratio of characteristic elemental lines from the coating and substrate material via laser-induced breakdown spectroscopy. It is shown that with increasing number of laser pulses and decreasing residual thickness, respectively, this ratio decreases logarithmically. Such a decrease has turned out to be independent of the substrate surface texture. However, some restrictions of the investigated approach were identified by additional microscopic measurements where an inhomogeneous layer growth as well as laser-induced delamination was ascertained. The impact of these effects on the detected ratio is thus discussed. The results finally represent a proof of principle as a basis for ongoing work for spectroscopic measurement of coating thickness on complexly shaped surfaces.

Graphical abstract