Effect of Tm2O3 on the properties of corundum‐mullite composite ceramics for solar heat transmission pipelines

Abstract

AbstractCorundum‐mullite composite ceramics appropriate for application in solar heat transmission pipelines were fabricated by the addition of Tm2O3 and sintered at atmospheric pressure. The results demonstrated that with the introduction of Tm2O3 (1–7 wt.%), the physical and mechanical properties, corrosion resistance, and thermal shock resistance of the composite ceramics were significantly enhanced. The sintered sample AT5 (with 5 wt.% of Tm2O3 added) showed the best overall performance at 1550°C. The residual bending strength remained higher than 186 MPa after corrosion with 20 wt.% H2SO4 solution and 10 wt.% sodium hydroxide solution. The reaction of Tm2O3 with the Al2O3–SiO2 system produced the Tm2O3–Al2O3–SiO2 liquid phase. This liquid phase eliminated the pores through viscous flow, resulting in a dense microstructure. Furthermore, more mullite and dithulium disilicate were generated after thermal shock cycles, and their inhibition of crack deflection and extension allowed the composite ceramics to achieve excellent thermal shock resistance (residual bending strength as high as 199 MPa). The prepared corundum‐mullite composite ceramics have a good potential for application in solar heat transmission pipelines.