ANALYSIS OF LAYERS - X-RAY MAPS OF CHANGE IN THICKNESS OBTAINED BY ELECTRON MACROPROBE

Surface coatings on steels can significantly change the properties of this material, thus the characterization of such thin films is an impo rtant objective of the steelmakers. The aim of the present work is to investigate a method of obtaining elemental compositions and thickness profiles of coatings using X-ray mapping. The analyses are carried ou t by electron probe micro analysis using a technique based on the phi- rho-Z model of the depth distribution of X-ray emission. Thickness X-r ay maps of multilayered coatings can be built using suitable computer software combined with an accurate calibration method. The software us ed in STRATA from SAMx (France). The analyser used is a Camebax SXmacr o from CAMECA. It is shown that, for the simple case of a chromium fil m (100 to 600 nm thick) on a steel substrate, the analysis can be perf ormed at a single excitation voltage of 20 keV. Of course, in a more c omplicated case, such as multilayers containing many elements it is ne cessary to work with several accelerating voltages. In a second exampl e, a thin film containing Fe, Cr, Mo, Si and Ti was deposited on the p revious chromium layer. With Strata computer software and our calibrat ion procedure it is possible to obtain the composition and the coating thickness variation in the regions where the him was not too thick fo r analysis.