摘要
采用溶胶-凝胶法和乙醇超临界干燥工艺,以无机铝盐为原料,制备完整块状的SiO_2-Al_2O_3复合气凝胶。通过傅里叶红外光谱仪(FT-IR)和X线衍射仪(XRD)研究气凝胶在热处理过程中物相结构的变化;采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对气凝胶的表面形貌和组织结构进行观察;采用N2吸附-脱附测试来研究热处理过程中气凝胶孔结构的变化。结果表明:SiO_2-Al_2O_3复合气凝胶中SiO_2相主要以无定形形式存在,而Al_2O_3相主要以针叶状或长条状的勃姆石多晶形式存在,当温度达到1 100℃时,复合气凝胶中开始产生莫来石相。随着热处理温度的升高,SiO_2-Al_2O_3复合气凝胶的比表面积逐渐减小,直到1 000℃时,比表面积仍高达416.23 m^2/g,同时高温热处理改善了气凝胶内部网络结构,使孔径分布更加均匀。
Monolithic SiO_2-Al_2O_3 composite aerogel using inorganic aluminum salt as raw material was prepared by a sol-gel method,followed by C2H5 OH supercritical fluid drying. The changes of phase structures during thermal treatment were characterized by Fourier transform infrared spectroscopy（ FTIR） and X-ray diffraction（ XRD） technique. The micro-morphology and structures were investigated by scanning electron microscope（ SEM） and transmission electron microscope（ TEM）. Nitrogen adsorptiondesorption isotherm was used to investigate the changes of pore structures during the heating process.Results showed that SiO_2 existed as amorphous state and Al_2O_3 mainly existed as boehmite consisited of fibrous particles and weblike microstructures. When the heat treatment temperature reached to 1 100 ℃,the mullite began to appear in the composite aerogel. The specific surface area decreased with the increase of thermal treatment temperature,but it remained 416. 23 m^2/ g until 1 000 ℃. Heat treatment process improved the quality of the three-dimensional network in the aerogel,and the pore distribution became uniformity after heat treatment.
出处
《南京工业大学学报（自然科学版）》
CAS
北大核心
2016年第2期7-14,共8页
Journal of Nanjing Tech University(Natural Science Edition)
基金
长江学者和创新团队发展计划(IRT_15R35)
江苏省科技支撑计划(工业)项目(BE2014128)
航空科学基金(201452T4001)
江苏省高校自然科学研究重大项目(15KJA430005)
江苏省产学研前瞻性联合研究项目(BY2015005-01)
江苏先进无机功能复合材料协同创新中心
江苏高校优势学科建设工程
江苏高校品牌专业建设工程
