Al/Al2O3 cermets by plasma spraying: Optical response of experimental and numerical materials

Normal hemispherical spectral reflectances of plasma sprayed Al₂O₃/Al cermets were acquired from visible to infrared wavelengths for several metal concentrations ranging from pure alumina to aluminium. The microstructure and the composition of the samples were carefully characterized to explain their optical response, highly dependent on volumetric and/or light scattering.

Besides their contribution to the knowledge of the microstructure, 2D SEM and 3D micro-tomography images were exploited to get statistical data in order to generate simplified numerical samples. A Monte Carlo ray-tracing model is then intended to reproduce experimental trends of the optical spectra and to determine relevant parameters.

Results show that the optical properties of coatings produced by plasma spraying can be adjusted and open the door to applications in fiels such as solar energy or aeronautics.