Improving dielectric properties of plasma sprayed calcium titanate (CaTiO3) coatings by thermal annealing

Self-supported CaTiO3 coatings prepared by plasma-spraying technology and effect of annealing on dielectric properties and microstructure of these coatings are studied in this work. A water stabilized plasma gun WSP (IPP ASCR, Prague) as well as a widely used conventional gas stabilized plasma gun GSP were employed. Prepared samples were annealed in air atmosphere up to 1170 °C. The work is focused on dielectric properties of these specimens. Relative permittivity and loss factor were measured in a frequency range of 30 Hz-30 MHz. Microstructure was studied using light microscopy, microhardness measurements, X-ray diffraction - including high-temperature XRD measurements, and X-ray photoelectron spectroscopy. The work studies the influence of annealing temperature on dielectric properties, crystalline structure and porosity of plasma deposited calcium titanate. Results obtained show significant improvement in CaTiO3 coating properties after thermal annealing.