自生长纳米纤维增强SiO_2气凝胶的制备和力学性能研究

Preparation and mechanical strength of SiO_2 aerogels enhanced by self-growing nano fibers

利用溶胶-凝胶法结合超临界干燥,并经高温热处理工艺制备出自生长锆氧、铝氧纳米纤维增强SiO_2复合气凝胶,通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X线衍射仪(XRD)、N_2吸附-脱附等测试方法对复合气凝胶的结构进行表征,并对试样的力学性能进行验证。结果表明:利用前驱溶液中酸碱不平衡的现象自生长出锆、铝氧纳米纤维,将金属氧化物和SiO_2前驱体在凝胶老化过程中复合成型后再经高温转化的方式实现增强纤维与气凝胶本体的结合,制备出轻质、高强度、耐高温、耐氧化的纳米纤维增强SiO_2复合气凝胶,压缩强度可达到6MPa以上。

The SiO_2 aerogels reinforced by the self-growing zirconia and alumina were synthesized using sol-gel technology and supercritical fluid drying,and converted to the high strength composite aerogels after high temperature heat treatment process. The structures of composite aerogels were analyzed by scanning electron microscopy（ SEM）,transmission electron microscopy（ TEM）,X-ray diffraction（ XRD）,specific surface area test,and the compressive strengths were measured. Results showed that zirconia and alumina nanofibers would grow with the p H imbalance in precursor solution,and the reinforcing fibers could be perfectly combined with gel body under the aging of metal oxide and SiO_2 gel precursor,and the composite aerogels were treated at high temperatures. The preparation composite SiO_2 aergels had characteristics of lightweight,high strength,high temperature resistance,and the mechanical compression strength could reach more than 6 MPa.