Application of infrared reflection spectroscopy for the analysis of hard coatings on metallic substrates

A method is presented for calculating the absorption spectrum, the film thi ckness and the index of refraction from IR reflection spectra. Considering real test conditions (partial incoherence, scattering) a routinely usable i nstrument was created with this direct calculation of the absorption spectr um, which provides a very good correspondence between the measurement and s imulation also without any initial information about the expected spectrum. This method is applied to characterize hard coatings deposited on iron sub strates by glow discharge assisted CVD processes with organic silicon and b oron compounds as precursors. In addition to the qualitative microstructura l characterization of these coatings, this method is suitable for a rapid, exact and non-destructive determination of the film thickness and the index of refraction.