硅酸钠添加量对多孔硅藻土陶瓷性能的影响

Effect of Sodium Silicate Addition Amount on Properties of Porous Diatomite Ceramics

以工业硅藻土细粉为原料,以硅酸钠为烧结助剂,采用发泡注凝法在1 000℃保温2h制备多孔硅藻土陶瓷,研究了硅酸钠添加量(0~5%,质量分数)对陶瓷物相组成、显微结构、气孔孔径和耐压强度的影响.结果表明:随硅酸钠添加量的增加,多孔硅藻土陶瓷中的方石英含量减少,鳞石英含量增加,烧结致密程度增大,气孔孔径呈现减小的趋势,耐压强度增大;当硅酸钠的质量分数为3%时制备得到具有多级孔结构的硅藻土陶瓷,该陶瓷的耐压强度为(1.13±0.08)MPa,比未添加硅酸钠的提高了约113%,其200℃时的热导率仅为(0.098±0.002)W·m^(-1)·K^(-1).

Porous diatomite ceramics were prepared by foam-gelcasting method after holding at 1 000 ℃ for 2 h with industrial diatomite fine powder as raw material and sodium silicate as sintering aid.The addition amount（0-5 wt%）of sodium silicate on the phase composition,microstructure,pore size and compressive strength of the ceramics were investigated.The results show that with increasing addition amount of sodium silicate,the cristobalite content decreased while the tridymite content increased in the porous diatomite ceramics,the sintering densification increased,the pore size showed a decreasing trend,and the compressive strength was improved.When the addition amount of sodium silicate was 3 wt%,the diatomite ceramics with a hierarchically pore-structure were obtained;the compressive strength was （1.13±0.08）MPa,which increased by about 113% comparing with that without sodium silicate,and the thermal conductivity at 200 ℃ was （0.098±0.002）W·m-1·K-1.