Reduced thermal conductivity of solid solution of 20% CeO2 + ZrO2 and 8% Y2O3 + ZrO2 prepared by atmospheric plasma spray technique

摘要

To reduce the thermal conductivity and improve the durability of ZrO2 based materials, coatings from different contents of 20% CeO2 + ZrO2 and 8% Y2O3 + ZrO2 are deposited by atmospheric plasma spray technique. The obtained coatings are characterized by X-ray diffraction, scanning electron microscopy and the thermal diffusivity/conductivity is calculated. Substitutional point defects are created in the coating which improves the phonon scattering thereby influencing the thermal conductivity. Pores and cracks are identified in the microstructure and quantitatively analyzed. Samples with higher concentration of defects provided minimum thermal conductivity which might be due to the enhanced phonon scattering. Among the prepared coatings, samples with 25% of 20% CeO2 + ZrO2 and 75% of 8% Y2O3 + ZrO2 provided minimum thermal conductivity in the temperature range 25-1200 degrees C. The prepared coatings are compared with the pure 8% Y2O3 + ZrO2 coatings. The solid solution of 20% CeO2 + ZrO2 and 8% Y2O3 + ZrO2 demonstrated lower thermal conductivity than the 8YSZ. The reduced thermal conductivity is attributed to the higher concentration of defects which improve the phonons scattering.