Fabrication And Properties Of Al₂O₃ Aerogel-SiO₂ Fiber Mat Composite

At present,environmental protection and energy issues around the world are becoming increasingly prominent.Thermal insulation materials can effectively reduce heat losses in the process of generation,transportation,etc.Thereby achieving the goal of energy conservation,consumption reduction and emission reduction,a thermal insulation material with good mechanical properties,low thermal conductivity and high temperature resistance has important research value and broad application prospects.Nano-porous-fiber composites are currently the focus of research on thermal insulation materials.In this experiment,Al₂O₃ aerogel-SiO₂ fiber was prepared by using sol-gel method with Al?NO₃?₃·9H₂O was used as the aluminum source,anhydrous ethanol?EtOH?and distilled water?H₂O?as the solvent,and propylene oxide?PO?as the coagulant.The mechanism of Al₂O₃ sol-gel process and the effects of water and propylene oxide amount on Al₂O₃ sol-gel were studied.At the same time,in order to further improve the thermal insulation performance of Al₂O₃ aerogel-SiO₂ fiber mat composites,the effects of different types of opacifiers and different amounts of sunscreens on the thermal conductivity of Al₂O₃ aerogel-SiO₂ fiber mat composites were studied.Finally,aluminum chloride hexahydrate was used as a precursor to improve the thermal insulation performance of the Al₂O₃ aerogel-SiO₂ fiber felt composite.The structure was characterized by scanning electron microscope?SEM?,projection electron microscope?TEM?,Specific surface and aperture analyzer?BET?,infrared spectrometer?IR?,and X-ray diffractometer?XRD?.At the same time,the thermal insulation performance of Al₂O₃ aerogel-SiO₂ fiber mat composite was tested by PTF.The thermal insulation performance of the material was tested and analyzed to determine the optimal process conditions for preparing the Al₂O₃ aerogel nanofiller as n?Al?NO₃?₃·9H₂O?:n?EtOH?:n?H₂O?:n?PO?=1:15:5.55:5.7 to obtain an Al₂O₃ aerogel-SiO₂ fiber mat composite material with excellent performance,which has good thermal insulation properties?the thermal conductivity at 35?is 0.028?W/m·K?,Good mechanical properties?Young's modulus of tensile fracture:6.59Mpa?and environmental stability?hydrophobic angle of 134.64°?.When the doping amount of TiO₂ is 10 mol.%,TiO₂?10 mol.%?-Al₂O₃ The aerogel-SiO₂ fiber mat composite has low thermal conductivity at 35?,its thermal conductivity is 0.021?W/m·K?,and after heat treatment at 600?for 2 hours,its thermal conductivity is 0.031?W/m·K?.When the doping amount of SiC is 0.5 mol.%,the thermal conductivity of SiC?0.5 mol.%?-Al₂O₃aerogel-SiO₂ fiber mat composite is the lowest at 35?,its thermal conductivity 0.022?W/m·K?,After heat treatment at 600?for 2 hours,its thermal conductivity is 0.025?W/m·K?.With aluminum chloride hexahydrate as the precursor,the 10 mol.%TiO₂-Al₂O₃ aerogel-SiO₂fiber felt composite material at 35?,its thermal conductivity is 0.021?W/m·K??.After heat treatment at 600?for 2 hours,its thermal conductivity is 0.034?W/m·K?.0.5 mol.%SiC-Al₂O₃ aerogel-SiO₂ fiber felt When the composite material is at 35°C,its thermal conductivity is 0.020?W/m·K?.After heat treatment at 600°C for 2 hours,its thermal conductivity is 0.025?W/m·K?.It could be seen that the types and amounts of opacifiers and aluminum salt precursors could help improve the thermal insulation performance and temperature resistance of Al₂O₃ aerogel-SiO₂ fiber mat composites.Finally,in this work,the thermal and thermal insulation properties of the Al₂O₃ aerogel-SiO₂ fiber mat composite were analyzed theoretically in combination with the physical and chemical properties of the Al₂O₃ aerogel-SiO₂ fiber mat composite.