Effect of MnO2 on Properties of SiC-mullite Composite Ceramics for Solar Sensible Thermal Storage

摘要

For improving the properties of Si C-mullite composite ceramics used for solar sensible thermal storage, Mn O_2 was introduced as sintering additive when preparing. The composite ceramics were synthesized by using Si C, andalusite, α-Al_2O_3 as the starting materials with non-contact graphite-buried sintering method. Phase composition and microstructure of the composites were investigated by XRD and SEM, and the effect of Mn O_2 on the properties of Si C composites was studied. Results indicated that samples SM1 with 0.2 wt% Mn O_2 addition achieved the optimum properties: bending strength of 70.96 MPa, heat capacity of 1.02 J·(g·K)-1, thermal conductivity of 9.05 W·(m·K)-1. Proper addition of Mn O_2 was found to weaken the volume effect of the composites and improve the thermal shock resistance with an increased rate of 27.84% for bending strength after 30 cycles of thermal shock(air cooling from 1 100 ℃ to RT).