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.

Al 2 O 3 -13 % wt TiO 2 thermal sprayed coatings exhibit good wear resistance under tribological conditions, thanks to their high toughness. Alumina/titania coatings with two different structures, and similar titania content, have been elaborated by atmospheric plasma spraying (APS). The aim was to compare the effect of the structure on hardness and wear resistance. As feedstocks were used Al 2 O 3 -13 wt % TiO 2 powders with two different structures: micrometer sized ones, with two size distributions (5 – 30 μm and 15 – 45 μm), and agglomerated nano-meter sized particles (grain diameters between 200 to 500 nm) with a size distribution between 10 and 45 μm. Coatings were sprayed onto low carbon steel (XC38) substrates with several spray parameters, the plasma forming gas used being mixtures of Ar and H 2 (45/15 and 53/17 SLM, respectively). Results show that, with the tribological conditions used in this study, the wear resistance of coatings principally depends of their hardness and not very much on the starting powder morphologies.