Towards quantitative depth-profile analysis using laser-induced plasma spectroscopy: investigation of galvannealed coatings on steel

Laser-induced plasma spectroscopy (LIPS) is applied to depth-profile analysis, with the particular goal of examining how LIPS depth profiles can be fully calibrated. For this purpose, we concentrate on the representative case of galvannealed coatings on steel (i.e. annealed zinc-coated steel). In particular, a method is proposed wherein the second derivative of the zinc intensity profile enables the determination of the coating/substrate interface position. Calibration for the major elements (iron and zinc) is based on a non-linear relationship between the iron-to-zinc line intensity ratio and the iron-to-zinc concentration ratio. Quantitative depth profiles of three elements (Al, Fe and Zn) are obtained for two galvannealed samples. The iron profiles are found to be in broad agreement with those obtained by transmission electron microscopy/energy dispersive X-ray spectrometry.