Thermal properties of Sm₂Zr₂O₇-NiCr ₂O₄ 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 Sm ₂Zr₂O₇. 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 Sm ₂Zr₂O₇, but the recovery of the thermal conductivity of rare-earth zirconate was relived or disappeared in the testing temperature range.