Fabrication and characterization of Pr6O11-HfO2 ultra-high temperature infrared radiation coating

Abstract In this study, pure HfO 2 and Pr 6 O 11 -HfO 2 coatings were prepared by atmospheric plasma spraying. The chemical compositions, morphologies, infrared radiation performances and thermal resistances of the coatings were characterized. The results showed that doping Pr 6 O 11 could effectively improve the infrared emittance of the HfO 2 coating. The HfO 2 coating doping with 10 wt. % Pr 6 O 11 exhibited the highest infrared emittance, which was 0.859 at room temperature and 0.883 at 1600 °C, correspondingly. This was mainly attributed to the oxygen vacancies, which created by the substitution of Hf 4+ by Pr 3+ , could introduce localized energy states within the HfO 2 band gap and increase the lattice distortion, producing lower symmetry vibrations. In addition, the Pr 6 O 11 -HfO 2 infrared radiation coating possessed high tensile adhesive strength and good thermal resistance, which could withstand a high temperature treatment at 1700 °C for at least 50 h without exfoliation, and there was only a slight reduction in emittance.