Spatial Mapping of Plasma Sprayed Coating Thickness Using X-Ray Fluorescence

The measurement of the spatial distribution of coating thickness of thin coatings applied by thermal spraying can be challenging. For non-magnetic metallic substrates and coatings, X-Ray Fluorescence (XRF) was employed for measuring coating thicknesses in the range of 15 to 60 μm. XRF is used to measure the ratio of atomic fluorescence peaks for an element in the substrate to an element in the coating. With appropriate calibration, the ratio of peak intensities gives the coating thickness for the spot sampled. Mass gain and cross sectional metallography are compared to XRF to determine accuracies and sensitivities of the techniques for plasma sprayed coatings.