Preparation and thermophysical properties of Ti4+ doped zirconia matrix thermal barrier coatings

There is an upper limited temperature of about 1200 °C for yttrium oxide partially stabilized zirconia coatings. With the increasing temperature of inlet gas (>1200 °C), new thermal barrier coatings are urgently needed to replace traditional yttrium oxide partially stabilized zirconia. Ti4+ ion doping has been recognized as an effective method to achieve this. In this work, a novel ceramic coating with low thermal conductivity at 1600 °C is synthesized, and the microstructure, chemical components, phase structures are analyzed. The thermal diffusivity and thermal conductivity of the as-sprayed coatings initially exhibited low values up to 1600 °C. The mechanism of low thermal conductivity is analyzed. The oxygen vacancies effectively reduce thermal conductivity, which can be proved by the ablation experiment (at 1600 °C). The effect of lattice defects caused by differences in the masses and radii of Ti4+ and Zr4+ ions on the phonon scattering coefficient is analyzed quantitatively. These results indicate that this coating is a promising candidate for thermal barrier coatings at high temperatures.