Scratch-test study of failure mechanism of zirconium dioxide plasma coatings obtained from solid and hollow microspheres

The paper investigates the regularities of formation of ceramic coatings based on zirconium dioxide from powder materials of composition ZrO2 + 7 % Y2O3 and ZrO2 + 5,5 % Y2O3 consisting of solid and hollow microspheres by high-energy plasma spraying. It was found that the formed coatings have a honeycomb-like cross-section with columnar structure of zirconium dioxide grains, low total porosity (4,1 and 4,7 %) and high hardness (9,65 and 12 GPa). The cohesive failure mechanism of ceramic coatings was established by the scratch test method, and quantitative indices of critical loads corresponding to cohesive strength were obtained. According to the results of comparative studies, the coating obtained from powdered material of solid microspheres has better performance properties than the coating applied from powdered material of hollow microspheres. The coatings are recommended for protection of thermally loaded parts of the hot path of gas turbine engines for different purposes.