Microstructure and performances of Gd2O3-added corundum–mullite ceramic composites for concentrated solar power applications

Abstract Gd2O3 was added to increase the properties of corundum–mullite ceramic composites by enhancing the microstructural densification using coal-series kaolin and α-Al2O3. The effect of Gd2O3 addition on the microstructure and properties of ceramic composites was explored. The results showed that the formation of Gd2O3–Al2O3–SiO2 liquid phase could improve the bending strength, hardness, and acid resistance, since such liquid phase promoted microstructural densification via a reaction between Gd2O3 and Al2O3–SiO2 binary system in this Al2O3-rich and SiO2-poor system. The precipitation of mullite and gadolinium disilicate during thermal shocks resulted in enhanced bending strength. In particular, sample AG5 (80 wt% Al2O3, 20 wt% coal-series kaolin, and 5 wt% additional Gd2O3) sintered at 1550 °C was considered as candidate for heat transmission pipeline for the optimum comprehensive performance.