Thermal properties of Sm2Zr2O7–NiCr2O4 composites

Rare-earth zirconate is one of the most promising candidate materials for the next generation thermal barrier coatings. However, at high temperatures the thermal conductivity of the rare-earth zirconate increases because of radiation. NiCr2O4, which can absorb the infrared photons intensely, was introduced to reduce the radiative thermal conductivity of Sm2Zr2O7. NiCr2O4 and Sm2Zr2O7 powders were prepared by coprecipitation method. The bulks of Sm2Zr2O7–x vol% NiCr2O4 (x=0, 5, 10, 15 and 20) composites were prepared by non-pressure sintering. The phase, microstructure and composition of the samples were characterized. The absorptivity and the thermal conductivity of the composites were also tested. The absorptivity of the composites was enhanced as increasing the content of NiCr2O4. The total thermal conductivities of the composites were higher than that of pure Sm2Zr2O7, but the recovery of the thermal conductivity of rare-earth zirconate was relived or disappeared in the testing temperature range.