Gadikota Greeshma, Zhang Fan, Allen Andrew
Department of Civil and Environmental Engineering, University of Wisconsin, Madison, WI 53706.
Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899.
Ind Eng Chem Res. 2017;56. doi: 10.1021/acs.iecr.7b02810.
Synchrotron-based multi-scale X-ray scattering analyses are used to connect microstructural changes to phase changes in kaolinite on heating from 30 °C to 1150 °C. Combined ultra-small-angle and small-angle X-ray scattering (USAXS and SAXS) data are modeled to determine the hierarchical morphology of kaolinite comprising nano-scale interlayer pores, meso-scale pores, and larger interparticle voids, while wide-angle X-ray scattering (WAXS) data reveal the simultaneous evolution of molecular phases in kaolinite. We found that the transformation of kaolinite to metakaolin corresponds to the disappearance of nano-scale porosity, and the onset of sintered phases such as mullite consistent with the overall reduction in porosity. The emergence of nanoscale particulate features on heating above 900 °C corresponds to the onset of sintered phases such as spinel and mullite. This study illustrates the application of multi-scale X-ray scattering measurements to connect the thermally induced phase changes with changes in pore structure and fine morphology evolution.
基于同步加速器的多尺度X射线散射分析用于将高岭土在从30°C加热到1150°C过程中的微观结构变化与相变联系起来。对组合的超小角和小角X射线散射（USAXS和SAXS）数据进行建模，以确定高岭土的分级形态，包括纳米级层间孔隙、介观尺度孔隙和较大的颗粒间空隙，而广角X射线散射（WAXS）数据揭示了高岭土中分子相的同步演变。我们发现，高岭土向偏高岭土的转变对应于纳米级孔隙率的消失，以及诸如莫来石等烧结相的出现，这与孔隙率的总体降低一致。在900°C以上加热时纳米级颗粒特征的出现对应于诸如尖晶石和莫来石等烧结相的开始。这项研究说明了多尺度X射线散射测量在将热诱导相变与孔隙结构变化和精细形态演变联系起来方面的应用。
