关键词: 镁砂颗粒, MgO-Al₂O₃-SiO₂系蓄热材料, 比热容, 蓄热密度

Abstract: To prepare high-performance thermal storage materials for solid electric heating energy storage boilers,MgO-Al₂O₃-SiO₂ thermal storage materials were prepared using bauxite and fused magnesia as the raw materials,and sulfite pulp waste liquid as the binder,pressing at 100 MPa into samples with the dimentions of 50 mm×50 mm and heat treating at 1 360 ℃ for 4 h.The effects of the magnesia addition (0,10%,30% and 50%,by mass) on the phase composition,microstructure,physical properties and thermal storage performance of the materials were studied.The results show that:(1)with the introduction of magnesia,the phase composition and structural morphology of the thermal storage materials are significantly changed,and the materials present a gradient structure of magnesia particles-annular pores-spinel/cordierite reaction layers-mullite;(2)as the magnesia addition increases,the bulk density,specific heat capacity,thermal storage density and thermal conductivity of the samples increase,indicating an improvement in the thermal storage capacity and heat efficiency of the materials;the cold compressive strength first increases and then decreases,while the thermal expansion coefficient first decreases and then increases; excessive magnesia will produce excessive liquid,forming defects in the materials,thus decreasing the strength;(3)the sample with 30% magnesia has the optimal comprehensive performance.

Key words: magnesia particles, MgO-Al₂O₃-SiO₂ thermal storage materials, specific heat capacity, thermal storage density