Evolution of microstructure and thermophysical properties of Y2Hf2O7/YAG composite ceramic prepared by solution combustion combined with pressure-less sintering

Composite ceramics were carefully designed to meet the challenges of more complex and demanding application scenarios, such as high-temperature environments where material performance is crucial. Y 2 Hf 2 O 7 /YAG ceramic powders were synthesized in one step using the solution combustion method. The approach ensures homogeneity and efficiency in the preparation process. The XRD analysis confirmed that the synthesized ceramics contain only the YAG and Y 2 Hf 2 O 7 phases, indicating a well-defined and stable composition. The introduction of YAG increase the interfacial structure between the phases, which inhibits the sintering of the composite ceramics. This results in a higher porosity and a decrease in the overall density of the materials. The thermal expansion and TG-DSC analyses demonstrated that the composite ceramics exhibit excellent high-temperature stability. Furthermore, the thermal conductivities of the Y 2 Hf 2 O 7 /YAG ceramics show a nonlinear variation with the increase of YAG content. When the ratio of Y 2 Hf 2 O 7 to YAG is 1:0.25, the lowest thermal conductivity (ranging from 0.70 to 1.26 W m −1 K −1 ) observed. This reduction in thermal conductivity is a key feature for materials used in thermal environmental barrier applications, as it contributes to minimizing heat transfer and improving overall insulation performance. Overall, Y 2 Hf 2 O 7 /YAG ceramics offer excellent high-temperature stability, low sintering tendency, and low thermal conductivity, making them ideal for thermal environmental barrier applications.