氩气热处理制备高热稳定性疏水Si O_(2)气凝胶

Preparation of Hydrophobic Silica Aerogel with High Thermal Stability by Argon Atmosphere Heat Treatment

提高疏水Si O_(2)气凝胶的热稳定性对拓展其保温隔热应用具有重大意义。为了避免空气氛围下热处理对疏水基团造成的热氧化分解,采用氩气氛围对疏水Si O_(2)气凝胶进行热处理,达到调控其热稳定性的目的。结果表明:经氩气氛围700℃热处理后,Si O_(2)气凝胶仍维持着良好疏水性,接触角约140°。在空气氛围下的差式扫描量热测试中,热流峰值达到584℃,与未热处理的疏水Si O_(2)气凝胶相比提高约300℃,热稳定性显著提高。这为提高疏水Si O_(2)气凝胶的热稳定性和安全性提供了新思路,奠定了疏水Si O_(2)气凝胶高温应用的新基础。

Improving the thermal stability of silica(Si O_(2))aerogel plays a crucial role in expanding its heat insulation application.In this work,heat treatment in argon atmosphere was adopted to avoid the thermal oxidative decomposition of hydrophobic groups,which inevitably occurred in the heat treatment in air atmosphere.Also,the physicochemical properties were analyzed.The results show that the hydrophobicity of Si O_(2)aerogels still maintains at a contact angle of 140°after heat treatment in argon atmosphere at700℃.In the differential scanning calorimetry test in air atmosphere,the peak temperature in exothermic reaction(T_(peak))of heat treated Si O_(2)aerogels reaches 584℃,which is approximately 300℃higher than that of untreated Si O_(2)aerogels,thus improving the thermal stability.The results obtained also indicate that hydrophobic Si O_(2)aerogels could be used at high temperatures due to the improved thermal stability and safety.