Preparation And Properties Of Alumina Nanofibers And Their Aerogel Materials

Alumina nanofiber aerogel is a porous material formed by cross-linking and stacking of alumina nanofibers to form a three-dimensional skeleton structure.It has broad application prospects in the fields of sound insulation and noise reduction,heat insulation and heat preservation.In this paper,alumina nanofibers with excellent flexibility and strength were first prepared by electrospinning technology combined with sol-gel method,and then the fibers were dispersed and introduced into gelling agent and high-temperature binder,and the aerogelation of alumina nanofibers was carried out by freeze-drying process.The preparation of the aerogel material was studied,the effect of sintering temperature on the aerogel structure was systematically discussed,and its mechanical properties were characterized.The main conclusions obtained from the study are as follows:(1)In the process of electrospinning,polyvinyl butyral(PVB)and polyvinylpyrrolidone(PVP)were used as spinning auxiliaries to prepare spinning solution,and it was found that the surface of alumina nanofibers prepared when PVB was selected was rough.,The interior is loose and porous,even if the grain size is small,the mechanical properties are poor,while the internal structure of the fiber prepared with PVP as an additive is dense,although the grain size is large,but the flexibility and mechanical properties are excellent.When the temperature rises to 1200°C,the phase composition changes from amorphous to?-Al₂O₃phase,and?-Al₂O₃ phase,?-Al₂O₃phase and?-Al₂O₃ phase transition phase appear in the middle,and the fiber diameter first decreases and then becoming steady.(2)The flexible alumina nanofibers prepared at a temperature of 600°C were stirred and dispersed,using silica sol as a high-temperature binder and agar as a gelling agent,and uniformly mixed to obtain a precursor slurry,which was freeze-dried and sintered at high temperature.Alumina nanofiber aerogels were prepared.With the increase of the amount of silica sol,the macroscopic size of the dried green sample and the sintered aerogel is more stable,and the oriented pores left after the growth and removal of ice crystals are easier to maintain after sintering.The fundamental reason is that the silica sol particles form the pore wall and coat the fibers on the pore wall,which effectively improves its mechanical stability.