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定向多孔陶瓷因具有良好的流体渗透性及力学性能越来越引起人们的广泛重视。综述了定向多孔陶瓷常见的制备工艺,分别介绍了阳极氧化工艺、生物模板工艺、添加造孔剂工艺、冷冻干燥工艺以及其他常见工艺的原理以及国内外发展现状,总结了各种工艺的特点,其中阳极氧化工艺主要用于制备高度定向周期排列的介孔结构,此法存在基体与多孔材料分离时产生环境污染问题;生物模板工艺主要利用天然木材为模板,通过渗透、热解、反应等工艺步骤直接复型其生物形态的定向孔结构,此法制备的定向多孔陶瓷气孔率较低、力学性能较差且其制备步骤较为繁琐等问题;添加造孔剂工艺是利用高长径比的造孔剂通过挤压或者施加磁场等方式使其定向排列从而得到定向孔,此法生产大型陶瓷产品时具有一定的优势;冷冻干燥工艺主要是冷冻凝固陶瓷浆料,使浆料中的溶剂定向生长为“冰晶”随后减压干燥以去除凝固相溶剂,从而制备出多孔陶瓷,此法制备的成品孔隙率易于控制且定向孔连通性良好。综述了定向多孔陶瓷作为陶瓷过滤器和交叉复合材料预制体的应用,并对其制备工艺进行了总结与展望。
Oriented porous ceramics have drawn more and more attention due to their good fluid permeability and mechanical properties. The preparation technology of oriented porous ceramics is reviewed. The principles of anodic oxidation process, biological template process, pore-forming agent adding process, freeze-drying process and other common processes as well as the development status at home and abroad are summarized respectively. The anodic oxidation process is mainly used for the preparation of highly oriented periodic arrangement of mesoporous structures. This method has the problem of environmental pollution when the substrate is separated from the porous material. The biological template process mainly uses natural wood as a template and uses techniques such as infiltration, pyrolysis and reaction The method comprises the following steps: directing the directional pore structure of the biological morphology, low porosity, poor mechanical properties and complicated preparation steps of the oriented porous ceramic prepared by the method; the technology of adding the pore-forming agent utilizes the technology of high aspect ratio Pore through the extrusion or the application of magnetic fields and other ways to make its orientation to obtain directional holes, this method produces large ceramic products have some advantages; freeze-drying process is mainly frozen solidified slurry, the slurry of the solvent directional growth For “ice crystal” and then dried under reduced pressure to remove the solidifying phase solvent to prepare a porous ceramic, Prepared porosity finished easily controlled and oriented continuous pores excellent. The applications of oriented porous ceramics as ceramic filters and prefabricated cross-shaped composites are reviewed. The preparation techniques are summarized and prospected.