Guangjin Chen,Cuiwei Li,Hao Li,Lu Wang,Kepi Chen,Linan An
Single-phase (Ce 0.2 Zr 0.2 Ti 0.2 Sn 0.2 Ca 0.2 )O 2-δ porous high-entropy ceramics have been in-situ fabricated by foam-gelcasting-freeze drying method at different temperatures. The microstructure, phase composition, and properties of the obtained ceramics were investigated. The results indicate that compared with other porous ceramics reported in the literatures, this type of ceramics exhibits excellent performance. The sample prepared at 1350 °C shows high porosity (88.6 %), low thermal conductivity (0.023 W m -1 K -1 ), and high compressive strength (1.48 MPa). The current study suggests that porous (Ce 0.2 Zr 0.2 Ti 0.2 Sn 0.2 Ca 0.2 )O 2-δ high entropy ceramics are promising candidates for thermal insulation applications.
Thermal insulation materials must exhibit superior mechanical properties alongside exceptional thermal insulation conductivity. However, traditional porous ceramics often struggle to meet these dual requirements simultaneously. In high-entropy materials, the phonon scattering induced by lattice distortion effects can significantly reduce the thermal conductivity of ceramics, thus opening new avenues for the design of novel thermal insulation materials. Inspired by the high-entropy effect, this study employed solid-state reaction methods to synthesize (Ce 0.2 Zr 0.2 Ti 0.2 Sn 0.2 Ca 0.2 )O 2−δ (CZTSC) high-entropy ceramics at various temperatures, investigating their phase constituents, microstructural characteristics, and mechanical properties, while exploring the optimal sintering temperature. Additionally, a pore-forming agent method was utilized to fabricate monophasic CZTSC porous ceramics with different porosities at 1400 °C. Specifically, when the pore-forming agent content was 20 wt%, the sample exhibited an apparent porosity of 42.82%, with a low thermal conductivity of 0.57 W·m − 1 ·K − 1 , a low thermal diffusivity of 0.406 mm 2 ·s − 1 , and a relatively high compressive strength of 32.49 MPa. The current investigation underscores the promising prospects of porous CZTSC ceramics in the field of thermal insulation.
Fabricating high-performance high-entropy ceramics (HECs) with complex geometries remains a challenge. Here, high-entropy fluorite (Ce 0.2 Zr 0.2 Ti 0.2 Sn 0.2 Ca 0.2 )O 2-δ ceramics were fabricated by digital light processing (DLP). The effects of slurry solid loading (76–80 wt%) on sintering behavior, microstructure, mechanical properties, and thermal transport were systematically investigated and compared with pressureless sintering. Increasing the solid loading to 80 wt% increased the green-body density, reduced linear shrinkage, and produced ceramics with a bulk density exceeding 5.0 g/cm³ (>88% theoretical density). EDS analyses revealed compositionally homogeneous microstructures without detectable micron-scale elemental segregation within the spatial resolution of the present measurements. DLP-80 HEFO exhibited the highest flexural and compressive strengths among the printed samples while maintaining low thermal conductivity values of 1.7–2.2 W·m⁻¹ ·K⁻¹ from 25 to 1000 °C. This work demonstrates that optimizing slurry solid loading provides an effective strategy for fabricating high-entropy fluorite ceramics with balanced densification, mechanical performance, and thermal-insulation capability.
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