Preparation And Properties Of Fiber Reinforced Silica Aerogels

With the increasing abundance of modern production and life,the requirement for materials is getting higher and higher.In the field of thermal insulation,thermal insulation material is an important research direction.SiO2 aerogel is a porous amorphous material with continuous three-dimensional network structure.SiO2 aerogel has excellent properties such as very low density,high adsorption capacity,good transparency,high porosity and low thermal conductivity.It is a new type of thermal insulation material.However,SiO2 aerogels have poor mechanical properties,and it is difficult to form,and it is easy to crack too.In this paper,the mechanical properties of SiO2 aerogels are enhanced by adding fiber reinforcements to suppress the cracking.Meanwhile,the thermal insulation performance of fiber oriented alignment is simulated and analyzed to optimize the distribution of fibers in aerogels.In this paper,tetraethyl orthosilicate(TEOS)was used as silicon source,and gl ass fiber as aerogel reinforcement.Two step sol-gel process was adopted to add fibr ous reinforcements before SiO2 sol was not gel.The gel was prepared by two step catalytic method and surface modified in mixed solution of absolute ethanol/three methyl Siloxane/hexane(EtOH/TMCS/N-hexane),and hexane(N-hexane)was clean ed.Hydrophobic SiO2 composite aerogels were obtained after atmospheric drying.Th e effects of gel time and fiber dosage on the block and physical properties of SiO2 aerogels were discussed.The X phase analysis,XRD,scanning electron microscopy(SEM),Fu Liye infrared spectroscopy(FT-IR)and BET adsorption method were use d to characterize the phase characteristics,microstructure,surface chemical groups an d pore structure of SiO2 aerogels.The results showed that the Si02 aerogels prepared by the ratio of tetraethyl orthosilicate:ethanol:water:N,N-twomethformamide=1:7:2:0.25 were the most excellent and the setting time was the most suitable.After the surface modification of glass fibers,adding fibers could get good mechanical properties and low thermal conductivity when the fiber content was 0.4%(mass fraction).The glass fiber composite aerogel material is used to make glass fiber felt composite aerogel thermal insulation material.Through the study of heat flux,thermal gradient and temperature field,it is found that the parallel arrangement fiber increases the heat conduction path,the heat flow distribution is uniform,reduces the heat loss of the fibers,reduces the overall thermal conductivity,and optimizes the distribution of the fiber in the aerogel.