Research On Broadband Infrared Absorbing Properties Of Silica Aerogels

Aerogels are the three-dimensional porous network structure materialswhich have the extremely low density and thermal conductivity, nanoscalestructure and wide pore size distribution. These properties are good to theinfrared absorption and should be explored in infrared stealth. silica compositecould be easily prepared because of the excellent specific surface area andporosity. The main contents are as follows:（1） In this paper, different silica aerogel substrates have been synthesizedusing teraethoxysilane （TEOS） or waterglass as silicon source respectively andby ambient, freeze and supercritical drying. The preparation technology ofcomposite aerogels was determined through the structure and property analysisof the substrates. The apparent density and specific surface area of the silicaaeroge substrate are0.0881g/cm³and957m²/g. These aerogel substrates have agood shielding effect to laser in1.06μm and8-12μm infrared frequency and aregood to prepare composite aerogels（2） The SiO₂/γ-Al₂O₃composite aeroges have been synthesized with bothphysical and chemical methods. The structure and property of the SiO₂/γ-Al₂O₃composite aeroges has been characterized. the results show that SiO₂and γ-Al₂O₃can be combined together well and the relative absorption intensity infar-infrared window enhanced with the increase of the γ-Al₂O₃（3） The SiO₂/β-DCH and SiO₂/TEAHCl composite aerogels have beensynthesized and characterized respectively. Results show that both of β-DCH andTEAHCl can be combined with SiO₂well. The β-DCH has been agglomeratedinto particles while the TEAHCl has been crystallized into clumps, bundles andbulks. Both of the two composites can absorb broadband infrared. The relativeabsorption intensity in mid-infrared window enhanced with the increase of aminesalts.The two composites have a good shielding effect to laser in1.06μm and8-12μm infrared frequency.（4） The SiO₂/γ-Al₂O₃/TEAHCl composite aerogel has been synthesized and characterized, which proves that the ternary system can combine together well.The apparent densities are0.31-0.47g/cm³. All composites are nonporous ormacroporous. But they have a good broadband absorption in3-5μm and8-14μm.The composite aerogels have a good shielding effect to laser in1.06μm. Howerethe shielding effect to8-12μm infrared frequency is not as good as ideal property...