溶胶-凝胶伴随相分离法制备多孔氧化锆块体材料

Preparation of Macroporous Zirconia Monoliths via Sol-Gel Process Accompanied by Phase Separation

以无机锆盐氧氯化锆(ZrOCl2·8H2O)为前驱体,聚氧乙烯(PEO,MV=106)为相分离诱导剂,环氧丙烷(PO)为凝胶促进剂,采用溶胶-凝胶伴随相分离制备孔径尺寸可控且骨架连续的多孔氧化锆块体材料,利用扫描电镜、X射线衍射、差热分析等测试手段对所制得块体材料进行了表征。结果表明:PO借助不可逆的开环反应提高体系的pH值,从而促进溶胶体系的凝胶化;PEO则诱导体系发生相分离,并获得共连续多孔块体;ZrO2干凝胶在热处理前呈无定形态,400℃热处理后有四方相晶体出现,800℃热处理后四方相基本都转变为单斜相;热处理所产生的晶型转变基本不影响块体材料的微观形貌。

ZrO2 monoliths with controllable cocontinuous macropores were prepared v/a a sol--gel process accompanied by phase separation with ZrOCl2· 8 H20 as a precursor in the presence of propylene oxide （PO） and poly（ ethylene oxide） （PEO）. The prepared ZrO2 gels were characterized by X-ray diffraction, scanning electron microscopy, and differential thermal analy- sis, respectively. The results show that the gelation of the system is mediated by PO as an acid scavenger, while PEO is added as a phase-separation inducer. The dried gels appear amorphous, and the crystalline phases of tetragonal ZrO2 exist after heat- treated at 400℃. When the heat-treatment temperature increases to 800 ℃, tetragonal ZrOz mostly turns into the monoclinic and well-defined macroporous structure in large dimensions can be obtained, indicating that the formation of crystalline phase does not spoil the morphology of Zr02 monoliths.