Effect of andalusite and zircon on the performances of cordierite-spodumene composite ceramics for solar heat transmission pipeline

Abstract

Cordierite-spodumene composite ceramics used for solar heat transmission pipeline were prepared via pressureless sintering from kaolin, talc, γ-Al2O3 and spodumene. Effects of andalusite and zircon on densification, mechanical properties, phase composition, microstructure and thermal shock resistance of the composite ceramics were investigated. The results showed that andalusite and zircon additives effectively affected mechanical strength and thermal stability of the composite ceramics. Expecially, sample B5 with 15wt% zircon additive sintered at 1360°C achieved the highest bending strength and thermal shock resistance. The bending strengths of the sample before and after 30 thermal shock cycles (wind cooling from 1100°C to room temperature) were 100.17MPa and 101.90MPa, respectively. XRD analysis indicated that the main phases of the sample before 30 thermal shock cycles were α-cordierite, spinel, corundum, α-quartz and zirconium silicate, while β-spodumene grains generated after thermal shock. SEM micrographs illustrated that the existence of zirconium silicate and β-spodumene at the grain boundaries after 30 thermal shock cycles endowed the composite ceramics with a high residual strength. It is believed that the cordierite-spodumene composite ceramics can be a potential material to apply in the field of solar thermal transmission pipeline.