Francis Blanchard1, Fabrice Pougoum1, Fadhel Ben Ettouil2, Bill Baloukas1, Christian Moreau2, Jolanta E. Klemberg-Sapieha1, and Ludvik Martinu1

1) FCSEL - Functional Coating and Surface Engineering Laboratory, Department of Engineering Physics, Polytechnique Montréal
2) Mechanical, Industrial and Aerospace Engineering, Concordia University

Yttria Stabilized Zirconia (YSZ) coatings with different thicknesses and porosity levels were fabricated using the suspension plasma spray (SPS) technique, and their optical properties were evaluated and compared with coatings conventionally prepared using the atmospheric plasma spray (APS). To enable optical characterization, free-standing layers were prepared by dissolving the substrate. The room temperature reflectance and transmittance of these coatings were evaluated using a spectrophotometer equipped with an integrating sphere in the wavelength range from 0.5 to 2.5 µm, and their absorption and scattering coefficients as a function of wavelength were evaluated using the inverse adding doubling (IAD) algorithm. Reflectivity predictably increases with thickness and the absorption coefficient is very low in the IR range for all samples. Results show that SPS coatings, which exhibit smaller pores and a lower porosity level compared to APS, have a higher reflectivity (~95% at 1.2 µm). This is attributed to how their porous microstructure offers a larger number of inner interfaces.