隔热材料的热导率与孔径分布的相关性研究

摘要

为了进一步研究不规则气孔的孔径分布对隔热材料热导率的影响，以板状刚玉粉、α-Al2 O3微粉、ρ-Al2 O3微粉和金属铝粉为主要原料，添加不同量（质量分数分别为0、5％、10％、15％、20％、25％和30％）的≤0．045 mm 的锯末作为造孔剂，以 PVA 溶液为结合剂，经配料、混练、成型、干燥和1550℃保温3 h 烧成后，制备了氧化铝质隔热材料试样。检测了试样的体积密度、总气孔率、闭口气孔率和热导率，采用扫描电子显微镜（SEM）和金相图像分析系统（MIAPS）对烧后试样进行了表征，然后借助灰色关联理论分析了试样热导率与其孔径分布的相关性。结果表明：随着锯末添加量的增加，试样的气孔率和平均孔径逐渐增大，热导率逐渐减小；＜2、2～6和＞18μm 的气孔对试样热导率有显著影响。%In order to investigate the effect of irregular pore size distribution on the thermal conductivity of in-sulating refractories further,alumina insulating refractories were fabricated using tabular alumina powder,α-Al2 O3 micropowder,ρ-Al2 O3 micropowder,aluminum powder,different amounts of sawdust (0,5%,10%, 15%,20%,25%,and 30% by mass,≤0.045 mm)as the pore-forming agent and PVA as the binder.After batching,mixing,shaping and drying,all the specimens were fired at 1 550 ℃ for 3 h.Then the bulk densi-ty,total porosity,closed porosity and thermal conductivity of the specimens were measured.Also,SEM and Micro-image Analysis and Process System (MIAPS)software were carried out to investigate the correlation of pore size distribution and thermal conductivity.The results show that with the increasing of sawdust,both the porosity and the average pore size increase gradually whereas the thermal conductivity decreases.The thermal conductivity is strongly affected by the 18 μm pores.