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

摘要： 为制备高性能的固体电热储能锅炉用蓄热材料,以高铝矾土和电熔镁砂为原料,亚硫酸纸浆废液为结合剂,在100 MPa下压制成50 mm×50 mm的试样,经1 360 ℃保温4 h热处理制备MgO-Al₂O₃-SiO₂系蓄热材料。研究镁砂的加入量(加入质量分数分别为0、10%、30%、50%)对该材料的物相组成、显微结构、物理性能及蓄热性能的影响。结果表明:1)引入镁砂后,蓄热材料的物相组成、结构形貌均发生明显改变,材料整体呈现镁砂颗粒-环状气孔-尖晶石/堇青石反应层-莫来石的梯度结构;2)随镁砂加入量的增加,试样的体积密度、比热容、蓄热密度和热导率增大,说明材料蓄热能力和热效率提升,常温耐压强度先升高后降低,热膨胀系数先降低后升高,过量的镁砂会产生过多液相,导致材料内部产生缺陷,强度降低;3)当镁砂的加入量为30%(w)时,材料综合性能最优。

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