Quantitative depth profiling of oxide scales on high-temperature alloys by means of glow discharge optical emission spectrometry

Owing to the change in the sputtering rate and the glow discharge conditions during the in-depth profiling of surface layers of varying chemical composition, the quantification of the emission line intensities is complicated. A calibration of the intensities measured at constant voltage is possible taking into account the actual sputtering rate and the influence of the discharge current on the optical excitation. By using the base material as reference for oxide scales, the intensity ratio of an emission line is corrected with respect to the sputtering rate and the discharge current intensity ratios. The specific emission yield does not depend on either the matrix or the bonding state of the analyte. The method was applied to oxide scales on nickel—chromium alloys.