Silica Aerogels Hydrophobic Modified And Ambient Pressure Dring

Silica aerogels from the sol-gel process derived from the amorphous solid material, the porous rate of 80-99.8%, the hole size and colloidal particle size l-100nm, respectively, and the scope of 2-60nm, is typical of nano-materials. General approach to the surface of the silica aerogels with large amount of hydroxyl, which makes it easy to absorb moisture in the air, water easily broken, the negative of its performance, in addition to supercritical drying process with high energy consumption, high-risk, non-consecutive affect the production characteristics of the widespread use of silica aerogels. Therefore to avoid conditions in supercritical drying of the gel and to improve the hydrophobic aerogels is to promote the wider use of the key.In this paper, the main research contents include: study of the hydrophobic silica aerogels prepared under ambient pressure, modifier concentration investigated the impact of its structure; studied mullite fiber reinforced hydrophobic silica aerogels; and inspected heat treatment temperature on the pore structure of silca aerogels.The main conclusions of this paper is as follows: Using TEOS (TEOS) as silicon source, trimethyl chlorosilane (TMCS) as a modifier, with the aging of the surface of hydrophobic modification, ambient pressure drying preparation of a high surface area hydrophobic silica aerogels. Hydrophobic silica aerogels and water contact angle of 145°, in the air for the thermal stability of 269℃; and specific surface area of 1035m~2/g, has the typical structural characteristics of aerogels.Adding Fiber Reinforced Mullite into blocks of silica aerogels good, no cracks and has a certain mechanical strength, has good hydrophobic properties.Silica aerogels heat-treated at different temperatures, the pore structure characteristics of markedly improved, 52.6 percent increase in average pore size, pore volume increased 45.9 percent, 32.2 percent lower density, specific surface area increased by 10.6%, reducing the ambient pressure drying of pore structure of aerogels.The establishment of hydrophobic silica aerogels theoretical model is derived to calculate the largest trimethyl chlorosilane modified the effect of 3.21/nm~2, and the best samples of the modified effect of 1.35/nm~2, corresponding effectively to rate of 42.06%.