Heterogeneous materials exhibit optical properties different from that of bulk materials. Porosity, grain boundaries and others heterogeneities act as scattering centers and cause modifications in optical properties. Indeed, the latter are closely linked both to intrinsic properties of materials as well as microstructural characteristics and manufacturing process.

The objective of this work is to establish relationships between the optical properties of yttria-stabilized zirconia plasma-sprayed coatings and their microstructural features.

In order to do this, coatings with significant differences in their microstructures have been realized and their hemispherical reflectance and transmittance over the 0.25-20µm wavelength range have been investigated.

The extinction coefficient which describes the decrease of light intensity due to absorption and diffusion in the matter was determined from the variation of transmittance with coating thickness. The Kubelka-Munk four-flux model was implemented to evaluate the ratio of the absorption coefficient and scattering coefficient from reflectance measurements. The Mie theory was applied to determine the scattering and absorption effective cross sections and correlate them with the microstructural features of coatings.