孔径分布特征对水热固化硅藻土使用性能的影响

Effect of Pore Width Distribution on the Working Properties of Hydrothermally Solidified Diatomite

为探讨托贝莫来石基建筑保温材料的孔结构-性能关系,将硅藻土与适量的氢氧化钙和水均匀混合后,经不同压力模压成型,在高温饱和水蒸气环境下反应形成具有不同孔径分布特征的水热固化样品。微观结构分析表明,随成型压力的提高,样品孔隙率显著降低,且主要为微米级及以上孔隙含量减小的贡献,尺寸100 nm以下孔隙含量变化不明显。使用性能方面,硅藻土水热固化体的力学强度和导热系数随样品表观密度的提高而明显增大,并表现出一定的方向性;与此同时,样品的软化系数与抗冻融循环能力也受到孔隙率的明显影响。

In order to explore the contribution of pore structure on the working properties of tobermoritebased heat insulator, the mixture of diatomite, calcium hydroxide and tap water in a pre-determined proportion was evenly dispersed and then coaxially compressed under the appreciable pressure, following by a process of hydrothermal solidification to prepare tobermorite-based specimens with a variety of pore width distribution. Microstructural characterizations by making use of scanning electron microscopy and mercury intrusion method certified the reduction of porosity with the increasing apparent density of the asprepared specimens, as the results of the elimination of the pores being larger than 1 micrometer, but less alternation was observed from the pores in the scale of nanometers. On the other hand, it has been found that due to the coaxial compaction, the mechanical strength and thermal conductivity increased evidently with the increasing apparent density, along with a tendency of anisotropic characteristics to some extent, while the corresponding water softening coefficient and the resistance to freeze-thaw cycling were upgraded with the reduction of total porosity.