原位复合碳增韧YSZ中空纤维支撑体的制备及烧结机理研究

Ceramic hollow fiber membranes can provide a very large area volume ratio, and they also have high strength, good thermal and chemical stability in comparison with polymeric membranes. Currently, researchers mainly focus on improvement of separation performance and mechanical strength, investigations on the flexibility of ceramic hollow fiber membranes rarely were reported. The microstructure of a ceramic hollow fiber membrane is a filter layer with nano-sized pores attached on a supported layer with micro-sized pores, in which the supported layer can achieve desirable mechanical strength after high temperature sintering at the expense of pore size and porosity of the supported layer. However, high temperature sintering hardly improve flexibility of ceramic hollow fiber supports. It was found that the bad flexibility of ceramic hollow fiber supports impeded development of ceramic hollow fiber membranes in industrial applications . In this study, we firstly proposed a method of in-situ synthesized carbon toughened the yttria-stabilized zirconia(YSZ) hollow fiber supports. The preparation, secondary stretching,thermal treatment, sintering and carbonization process of the YSZ hollow fiber supports will be investigated. The mechanism of in-situ synthesis of fibroid carbon(Cf) in the YSZ hollow fiber supports will be explored. The influence of sinter aids on the interfacial microstructure and bonding strength of the Cf/YSZ composite. Moreover,the fracture toughness of the YSZ hollow fiber supports will be characterized,which is intent to provide a novel method for the improvement of flexibility and manipulation in the porosity of the YSZ hollow fiber supports,and then to promote development of characterization technique for the flexibility of ceramic hollow fiber membranes.

陶瓷中空纤维膜具有耐高温、耐酸碱和装填密度高等优点，目前国内外学者主要关注其分离性能和机械强度的提高，关于陶瓷中空纤维膜韧性的研究极少报道。陶瓷中空纤维膜由大孔径支撑体和小孔径过滤层构成，其中支撑体需要高温烧结获取良好的机械强度，然而高温烧结无法改变陶瓷材料的脆性特征，并且导致支撑体的孔隙率降低，因此限制了陶瓷中空纤维膜工程实际应用。本研究提出一个原位合成纤维形态碳材料Cf来提高YSZ中空纤维支撑体韧性的方案，将对YSZ中空纤维支撑体的制备、二次拉伸以及热处理和烧结碳化工艺中的关键问题进行攻关，探索在YSZ陶瓷颗粒中原位合成Cf增韧相的机理，分析添加烧结助剂对Cf/YSZ复合材料界面结合强度的影响，研究原位复合碳增韧YSZ中空纤维支撑体的断裂韧性，为低温烧结条件下提高YSZ中空纤维支撑体的韧性和孔隙率提供一个新思路，并且为建立陶瓷中空纤维膜韧性测量评估方法奠定基础。

陶瓷中空纤维膜具有耐高温、耐酸碱、装填密度高等优点，目前国内外学者主要关注其分离性能提高，对提高机械强度研究较少。陶瓷中空纤维膜由大孔径支撑体和小孔径过滤层构成，其中支撑体需要高温烧结获取良好的机械强度，然而高温烧结会导致支撑体的孔隙率降低，因此限制了陶瓷中空纤维膜工程实际应用。项目组通过原位合成碳材料来制备C/YSZ中空纤维支撑体，获得了兼有较高力学性能和孔隙率的中空陶瓷纤维，对YSZ中空纤维支撑体的制备、烧结碳化中的关键问题进行攻关，探索了在YSZ陶瓷颗粒中原位合成碳材料的机理，并系统研究了温度、含碳量及碳形态分布对中空纤维力学性能的影响，提出了一种新机制强化YSZ中空纤维支撑体，进而为强化YSZ多孔陶瓷提供一个新思路。依托本项目经费资助，已在Carbon, Materials and Design, Journal of the American Ceramic Society, Corrosion Science等国际知名期刊发表文章10篇。