用于隔热保温的多孔氧化铝陶瓷的制备与研究

Preparation and Research of Porous Alumina Ceramics for Thermal Insulation

多孔氧化铝陶瓷具有耐高温、低热导率等特点,是工业窑炉的隔热保温的首选材料。实验以α-Al_2O_3、煅烧铝矾土、苏州土为主要原料,采用物理发泡和注浆成型结合的方法制备了具有高气孔率、低热导率的多孔氧化铝陶瓷样品。通过正交实验确定了发泡剂的最佳配方为SDS添加量为0. 5 g·L^(-1)、CTAB添加量为0. 3 g·L^(-1)及水质量分数为50wt%。并探究了烧成温度对多孔氧化铝陶瓷样品的物理性能、相组成、热导率的影响,结果表明,经1500℃烧成后的最佳配方样品吸水率为13. 71%,气孔率为33. 14%,体积密度为2. 42 g·cm^(-3),在300℃下测得热导率为0. 83 W·m^(-1)·K^(-1)。本实验制备的多孔氧化铝陶瓷样品的相组成为莫来石和刚玉,由于具有大量的气孔,相同能量下气体激发出的声子数量远少于固体,热导率远远低于固体,导致热导率低。

With the characteristic of high temperature resistance and low thermal conductivity, porous alumina ceramics have already become the preferred materials for thermal insulation in industrial kilns. Using α-Al2O3, calcined bauxite and Suzhou clay as main raw materials, porous alumina ceramics sample was prepared by means of physical foaming and grouting combination. Through the multiple orthogonal experiments, the best formula of the foaming agent is determined by orthogonal experiment is 0.5 g·L^-1 for SDS, 0.3 g·L^-1 for CTAB and water mass fraction 50wt%. Besides, the effects of sintering temperature on physical properties, phase compositions and thermal conductivity of porous alumina ceramics were investigated. The experimental results show that when the best formula sample sintered at 1500 ℃, the water absorption rate is 13.71%, porosity is 33.14%, bulk density is 2.42 g/cm^-3 , and it has the thermal conductivity of 0.83 W·m^-1 ·K^-1 measured at 300 ℃. The phase compositions of porous alumina ceramic samples prepared in this experiment is mullite and corundum. Because porous alumina ceramics have a number of pores, and the number of phonons excited from gas is far less than that of solid under the same energy, thus the thermal conductivity is far lower than that of solid, resulting in low thermal conductivity.