Alumina aerogels with unidirectional channels under different freezing temperatures during freeze casting—Part I: Control and analysis of pore channels
Alumina aerogels with unidirectional channels under different freezing temperatures during freeze casting—Part I: Control and analysis of pore channels
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DOI：
10.1016/j.ceramint.2020.02.144
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发表时间：
2020-06
影响因子：
5.2
通讯作者：
F. He;Wen-Jin Li;Lijuan Yang;Zhu Zhen;Liang Zhou;Xin Zhang;Xiaodong He
中科院分区：
文献类型：
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作者：
F. He;Wen-Jin Li;Lijuan Yang;Zhu Zhen;Liang Zhou;Xin Zhang;Xiaodong He
以薄水铝石水溶胶和氧化铝纳米粉末为固溶体，在不同的冻结温度下制备了单向氧化铝气凝胶(AAs)。为了了解不同冻结参数下的多孔结构特征，实时记录了不同冻结温度下指定位置的冻结参数。采用傅立叶变换红外光谱(FT-IR)、X射线衍射仪(X射线衍射仪)、压汞测孔仪(MIP)和扫描电子显微镜(SEM)对其官能团、物相组成、微观结构和孔道特性进行了研究。详细探讨了不同冻结参数下AAS单向孔结构的变化规律及其影响因素。结果表明，AAs在冰晶生长方向上具有单向多孔结构特征。随着冻结温度的降低，降温速率和冰锋速率(VEF)增大，结构波长(λS)减小。λ与Vff之间的关系近似满足幂函数，这可能与含有纳米颗粒的均匀稀溶液有关。
Unidirectional alumina aerogels (AAs) were prepared by simultaneously using boehmite hydrosols and alumina nano-powder as solid solutes at different freezing temperatures. In order to understand the porous structural characteristics under different freezing parameters, the real-time frozen parameters were recorded at the designated positions under different freezing temperatures. Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) were used to investigate the functional groups, phase composites, microstructures and porous characteristics. The regularities and influence factors of unidirectional porous structures of AAs were detailedly explored under different frozen parameters. The results show that the AAs are characterized with unidirectional porous structures at the direction of ice-crystal growth. The cooling rate and ice front rate (vinf) increase and the structure wavelengths (λs) decrease with the decrease of the freezing temperature. The relationship betweenλandvinfapproximately satisfies a power law, which perhaps is related to the uniform dilute solution containing nanoparticle.