Studies On SiO₂Airgel Composite Sheet Reinforced By Asbestos Wool Fiber

Aerogels are mainly refers to the light nanometer solid materials, which consist of thenanometer level superfine particle, conglomerating nano-porous three-dimensional network,and the network pore is filled with gaseous dispersive medium. Because of the aerogelmaterial chainlike or bead-like structures, internal diameter is relatively small, but also for themesoporous connected, so that thermal conductivity aerogels rate is relatively low, but the gelstrength of pure gas is low, cannot obtain the widespread application, so the need to join thetoughening materials to make up for its shortcomings.In the thesis we use the asbestos wool fiber and glass fiber as reinforcing material,asbestos wool fiber flexibility is strong, and have excellent fire performance, will increase itstoughness for SiO₂aerogel on one hand, on the other hand, but also can reduce the thermalconductivity. Short glass fiber added in small amounts, to support the frame, therebyincreasing the flexural, compressive strength.Silica aerogels were prepared by sol-gel method with ambient drying technique. adoptthe industrial water glass as raw materials, asbestos wool fiber and glass fiber as reinforcingmaterial. The basic parameters of the material: density of0.20g/cm3, shrinkage rate of3.9%,porosity of80%, most of aperture lower than100nm, the effective thermal conductivity of0.024W/m K, compressive strength of4.9MPa, bending strength of1.75MPa.In the thesis, we study the mechanism of Sol-gel wich used water glass,and thepreparation process of SiO₂aerogels reinforced by asbestos fiber. Through discussing thesetting time, density, volume shrinkage, strength, thermal conductivity in different ratio.Theresults show that the best technology ratio is water glass/water/ethanol/stone cotton fiber/glass fiber/sodium fluosilicate/dispersant=1/0.4/0.04/0.02/0.002/0.06/0.002, Thesuggestion of adopting the preparation temperature is from20to25℃.