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Preparation and Performance Optimization of the Phosphate Insulating Material

Author: ZhenLiLi
Tutor: ZhouYuXiang
School: Harbin Institute of Technology
Course: Physical and chemical
Keywords: high temperature SiO2xerogel Al2O3-SiO2composite xerogel phosphateadhesive multilayer insulation enough statement
CLC: O648.17
Type: Master's thesis
Year: 2013
Downloads: 72
Quote: 0
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Abstract


Spacecraft re-entry, will largely suffer more severe aerothermal and aerodynamic,so researchers usually consider first meet the aerodynamic conditions, to prevent aspacecraft design/Heat，Because of this design avoids the body of the spacecraft cannot be re-burned aerodynamic heating, so as to ensure the space for the internal deviceat the appropriate temperature range to normal operation of the work. Thermalprotection system is to determine the success of spacecraft design is one of the keytechnologies, and its low quality, high efficiency, and high-temperature thermalprotection system insulation structure is an important consideration in the design of.Meanwhile, because of its low density airgel and low thermal conductivity, has been thefocus of research at home and abroad.This paper uses a pressure drying method and the sol-gel method to prepare silicaxerogels and Al2O3-SiO2composite xerogel.Preparation of SiO2xerogel TEOS （TEOS） as the silicon source, ethanol as solvent,using the first two steps after acid base catalysis for the sol-gel process. Bycombination with the previous preparation of the experiment and experience, todetermine the optimal experimental conditions, namely: the reaction ratio of TEOS:H2O: ethanol （molar ratio）=1:4:7; Hydrolysis and condensation reaction temperatureat between50℃-55℃; selection hydrolyzed under acidic conditions, the reaction timeis15-20min; The volume ratio TEOS/ethanol=7:3, at the reaction temperature arecompletely immersed alcohol gel72h, soak done three times, each time24h; Whereinthe organic solvent may be replaced with cyclohexane; drying conditions ofatmospheric pressure50℃.Al2O3-SiO2xerogel in the preparation of composite aluminum component usuallycheaper Al （NO3）39H2O to provide a network structure of silicone alkoxide solutionto provide. Then using a variety of analytical testing methods, Al2O3-SiO2xerogelcomposite microstructure, pore structure were analyzed.This paper analyzes the multi-layer insulation structure heat transfer mechanism,based on trying to develop a new type of high-temperature multi-layer insulationstructure. And this structure of the insulation material of quartz fiber cloth substrate tocompare the temperature of the adhesive agent is used as the spacer layer, and withAl2O3-SiO2xerogels as insulating filler compound.The new high-temperature multi-layer insulation structure advantage is that thevery low thermal conductivity of the gel used as thermal dry blended with the filler inthe adhesive, so as to achieve the thermal insulation effect. Through the multi-layer insulation structure Preparation and thermal properties of the theoretical analysis,guidelines for the further study direction and provides an experimental and theoreticalbasis.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Colloid chemistry ( physical and chemical dispersion system ) > Colloid > Gel and soft
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