Formation and investigation of plasma nanostructured hafnia coatings

Abstract

Nanostructured coatings HfO2-9wt%Y2O3 were obtained by plasma spraying in vacuum using supersonic nozzle creating Prandtl-Mayer expansion fan. The coatings were investigated by scanning electron microscopy, X-ray diffraction analysis, and synchronous thermal analysis (differential scanning calorimetry, thermogravimetric analysis, and differential thermogravimetric analysis) in the temperature range of 401600C. The coatings are predominantly characterized by the nanostructured globular structure. Thermal analysis showed a peak corresponding to the exothermic reaction in the temperature range of 14001600 C, accompanied by a mass loss. c-HfO2 phase remained in the coating after thermal analysis with a decrease in the lattice parameter a from 5.18 Å to 5.13 Å.