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

In this study, pure HfO2 and Pr6O11-HfO2 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 Pr6O11 could effectively improve the infrared emittance of the HfO2 coating. The HfO2 coating doping with 10 wt. % Pr6O11 exhibited the highest infrared emittance, which was 0.859 at room temperature and 0.883 at 1600 degrees C, correspondingly. This was mainly attributed to the oxygen vacancies, which created by the substitution of Hf4+ by Pr3+, could introduce localized energy states within the HfO2 band gap and increase the lattice distortion, producing lower symmetry vibrations. In addition, the Pr6O11-HfO2 infrared radiation coating possessed high tensile adhesive strength and good thermal resistance, which could withstand a high temperature treatment at 1700 degrees C for at least 50 h without exfoliation, and there was only a slight reduction in emittance.