Abstract: This work aims at finding an effective and low-cost new process for the preparation of porous aggregates,while alleviating the pressure of industrial solid wastes.Porous mullite ceramic-based aggregates were developed through low-temperature sintering using low-voltage electroceramic wastes and secondary aluminum dross as the main raw materials,and activated carbon powder as the pore-forming agent.The influence of the secondary aluminum dross addition (5 mass% to 40 mass%) on the properties of the samples was studied.The results show that:(1)with the increasing addition of secondary aluminum dross,the bulk density of the samples gradually decreases,while the apparent porosity gradually increases,and finally both tend to be stable;the linear shrinkage ratio first slightly increases and then decreases,and the cold compressive strength gradually decreases;(2)the addition of secondary aluminum dross promotes the formation of mullite crystalline nuclei,reduces the viscosity of the alumina-silica liquid phase,making it easier for internal gases to diffuse through the liquid phase to the material surface,forming large pores;moreover,the increase in the linear growth rate of mullite crystals accompanied by volume expansion further inhibits the sintering shrinkage of the liquid phase;the decrease in the cold compressive strength of the samples is related to the decrease in the liquid phase viscosity;after cooling to room temperature,a coating of alumina-silica glass phases forms on the surface of the aggregates,reducing the number of micropores and increasing the number of macropores,leading to increased stress concentration around the pores;(3)when the secondary aluminum dross addition is 25 mass%,the comprehensive performance of the sample is optimal.

Key words: low-voltage electroceramic wastes, secondary aluminum dross, mullite, porous aggregates, pore-forming agent

摘要： 为找到一种有效且低成本的多孔骨料制备新工艺,同时缓解工业固废对社会、环境和经济产生的压力,以低压电瓷废料和二次铝灰为主要原料,活性炭粉为造孔剂,采用低温烧结法制备了莫来石陶瓷基多孔骨料,研究了二次铝灰加入量(加入质量分数为5%~40%)对试样性能的影响。结果表明:1)随着二次铝灰加入量的增加,试样的容重逐渐降低,而显气孔率逐渐增加,最终两者均趋于稳定,线收缩率先略微增加后降低,室温压缩强度逐渐降低。2)二次铝灰的加入一方面促进了莫来石晶核的形成,并降低了铝硅液相的黏度,从而使内部气体更容易通过液相扩散到材料表面,形成较大的孔隙;另一方面莫来石晶体线生长速率增加伴随的体积膨胀进一步抑制了液相的烧结收缩。室温压缩强度下降与液相黏度降低有关,冷却到室温后骨料表面形成一层铝硅玻璃相涂层,微孔数目降低,大孔隙数目增加,导致孔隙周围应力集中增加。3)当二次铝灰加入量为25%(w)时,试样的综合性能最优。

关键词: 低压电瓷废料, 二次铝灰, 莫来石, 多孔骨料, 造孔剂