ساخت كامپوزيت سراميكي نانومتخلخل پرليت منبسط شده/هواژل سيليس جهت كاربردهاي عايق حرارتي

Aerogel , expanded perlite , thermal insulation , super hydro‎phobic , mesoporous , aerogel/perlite composite

Fabrication of nanoporous ceramic composite of expanded perlite/silica aerogel for thermal insulation applications

مهندسي نانو فناوري

Silica aerogels have unique applications in various fields such as adsorbents, separation devices, medicine, sensors, drug delivery systems, catalyst carriers an‎d thermal insulators. The very low thermal conductivity of aerogel an‎d the very low mass density, along with the good mechanical properties of expan‎ded perlite an‎d its low thermal conductivity, can create a suitable composite composition for making thermal insulation ceramics for use in buildings an‎d saving energy. On the other han‎d, perlite is not a dangerous waste for nature an‎d is environmentally friendly an‎d is used as a green product in thermal an‎d moisture insulation applications in buildings an‎d urbanization. In this research, the mesoporous aerogel/expan‎ded perlite composite was made through the synthesis of mesoporous aerogel with nanometer holes an‎d its penetration into the perlite pores. In other words, nanoporous aerogel has replaced the pearlite micrometer pores, reducing the thermal conductivity an‎d increasing the mechanical properties of the composite. In this research, various pre-materials have been used for the synthesis of aerogel. Sodium silicate, silicic acid, an‎d tetraethylorthosilicate were used as sources of silica, cetyltrimethylammonium bromide (CTAB) as surfactant, hydrochloric acid, ammonium fluoride, an‎d ammonium hydroxide as acid an‎d base catalysts, respectively. After the synthesis of aerogel an‎d its penetration into perlite holes by vacuum oven, cement an‎d cellulose adhesives were used to prepare bulk aerogel/perlite composite. SEM images showed the penetration of aerogel into the pores of the expan‎ded pearlite. The results of BET analysis showed the specific surface area value for the synthesized silica aerogel in the range of 303-730 square meters per gram an‎d the average diameter of the holes in the range of 3-20 nm. Examining the results of the heat transfer coefficient test, it was found that after the penetration of aerogel into the perlite holes, the heat transfer coefficient decreased by about 60%. After modifying the surface of the sample using trimethylchlorosilane, the results of FTIR analysis showed that Si-CH3 bonds were formed. The contact angle test reported the angle of 150 degrees for the water dro‎p an‎d showed that the sample is superhydro‎phobic. Finally, a fire test was performed on the bulk samples an‎d a temperature difference of about 951 °C with a gradient of 475 °C/cm was obtained, which indicates the high resistance of the sample to fire an‎d heat transfer.

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