The introduction of porous structures into high-entropy ceramics is expected to further improve its thermal insulation performance.In this work,a series of novel rare-earth-niobate high-entropy ceramic foams((Dy_(0.2)...The introduction of porous structures into high-entropy ceramics is expected to further improve its thermal insulation performance.In this work,a series of novel rare-earth-niobate high-entropy ceramic foams((Dy_(0.2)Ho_(0.2)Y_(0.2)Er_(0.2)Yb_(0.2))_(3)NbO_(7))with hierarchical pore structures were prepared by a particle-stabilized foaming method.Atomic-scale analysis reveals that high entropy causes atom displacement and lattice distortion.The high-entropy ceramic foams exhibit high porosity(90.13%-96.13%)and ultralow thermal conductivity(0.0343-0.0592 W/(m·K))at room temperature.High-entropy ceramic foam prepared by a 20 wt%slurry sintered at 1500℃has the porosity of 96.12%and extremely low thermal conductivity of 0.0343 W/(m·K).The existence of walls and secondary pores contributes to reduced thermal conductivity.There is a temperature difference of over 800℃between frontside and backside of the sample under fire resistance test.The research indicates that these as-prepared high-entropy ceramic foams are expected to be promising thermal insulation materials.展开更多
基金supported by the National Natural Science Foundation of China(No.52072301)the State Key Laboratory of Solidification Processing(NPU)(No.2021-TS-08)+3 种基金the State Key Laboratory of New Ceramic and Fine Processing Tsinghua University(No.KFZD202102)the China-Poland International Collaboration Fund of National Natural Science Foundation of China(No.51961135301)the Fundamental Research Funds for the Central Universities(No.D5000210722)State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(No.P2020–009)。
文摘The introduction of porous structures into high-entropy ceramics is expected to further improve its thermal insulation performance.In this work,a series of novel rare-earth-niobate high-entropy ceramic foams((Dy_(0.2)Ho_(0.2)Y_(0.2)Er_(0.2)Yb_(0.2))_(3)NbO_(7))with hierarchical pore structures were prepared by a particle-stabilized foaming method.Atomic-scale analysis reveals that high entropy causes atom displacement and lattice distortion.The high-entropy ceramic foams exhibit high porosity(90.13%-96.13%)and ultralow thermal conductivity(0.0343-0.0592 W/(m·K))at room temperature.High-entropy ceramic foam prepared by a 20 wt%slurry sintered at 1500℃has the porosity of 96.12%and extremely low thermal conductivity of 0.0343 W/(m·K).The existence of walls and secondary pores contributes to reduced thermal conductivity.There is a temperature difference of over 800℃between frontside and backside of the sample under fire resistance test.The research indicates that these as-prepared high-entropy ceramic foams are expected to be promising thermal insulation materials.
