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

There is an upper limited temperature of about 1200 degrees C for yttrium oxide partially stabilized zirconia coatings. With the increasing temperature of inlet gas (>1200 degrees 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 degrees 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 degrees 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 degrees 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. (C) 2018 Elsevier B.V. All rights reserved.