The Hydrophobicity Sio <sub> 2 </ Sub> Aerogels And Ag / Sio <sub> 2 </ Sub> Composite Airgel Preparation And Performance,

SiO2 aerogels have many special properties in mechanics, acoustics, electrical, optical and thermal aspects, owing to their special strueture, such as nanometer particles, network structure and huge specific surface area. So SiO2 aerogels have wide application prospects in basic research and applied research. Using sol-gel and supercritical drying technology preparation SiO2 aerogels are easily absorb water. Under high temperature moisture to evaporate cause aerogels structure collapses, thereby the value of SiO2 aerogels have been reduced in industrial application. Therefore, preparation hydrophobic SiO2 aerogels to improve SiO2 aerogels practical applications has the extremely vital significance.Because nanocomposites excellent performance, and metal doped SiO2 composite aerogel either as structural materials, but also as a function of material, is a very important research subject in nanocomposite materials, has been more and more attention and research. Nanosize silver particles are widely used in antibacterial material and catalysis, so the structure of preparation of doped Ag/SiO2 composite aerogels can improve the stability of the metal nanoparticles Ag, which makes the metal Ag nanoparticles to be better use in catalytic, sterilization areas.This paper respectively with in situ method and surface respectively post-processing, hydrophobic silica aerogel was prepared using tetraethyl orthosilicate (TEOS) as precursors and trimethylchlorosilane (TMCS) as the hydrophobic modification in atmospheric dry conditions. And dry control chemical additive DMF was added in sol-gel process. SiO2 aerogel prepared by in situ method and surface respectively post-processing is done Contrast and analysis, through various characterization methods.Following conclusions:DMF can effectively restrain SiO2 aerogel cracking. SiO2 aerogel preparaed by in situ method was white powder, and SiO2 aerogel preparaed by surface respectively post-processing is colorless transparent block. All of them were amorphous network porous structure and composition of the skeleton of SiO2 aerogels were an uniform spherical particle. SiO2 aerogel prepared by in-situ hydrophobic modification process has higher specific surface area.The aerogel became hygrophilous from hydrophobic when heated 300℃.There were not differential thermal peak heating to 900℃, quality is basically unchanged.Based on the preparation of the modified SiO2 aerogel, in this paper, Using sol-gel and ambient pressure technology, the different silver content Ag/SiO2 composite aerogel was prepared, using tetraethyl orthosilicate (TEOS) as silicon source, in adding sol-gel process of AgNO3 and KH-550 reactants, and using of formaldehyde pollution. And samples were characterized through various characterization methods. By the analysis of experimental results, the following conclusions:the doped silver particles have good face-centered cubic structure, And with the increase of the silver content of the compound system and heat treatment temperature, the size of the average silver grains increased gradually. The Ag/SiO2 composite aerogel has good thermal stability at 900℃below.