Study On The Ultrasonic Modification And Microstructure For Aerogel

Aerogel is a low-density, porous, non-crystalline, nanometer materials, whose continuous network structures can be controlled and tailored at the nanoscale. Due to their special network structures and larger specific surface area, the carbonized aerogel is widely used in the field of mechanics, acoustics, electricity, calorifics and optics.This dissertation has firstly developed ultrasonic heating process to modify carbonized aerogels in the preparation of resorcinol-formaldehyde organic aerogel, which increased the gelation speed, attains to the destination of shortening the preparation time of aerogels, increasing the quality of aerogels, and reducing the cost of aerogel's preparation. Several kinds of carbonized aerogels are prepared according to the modified technology process. The microstructures of the new developed carbon aerogels was investigated by means of low-temperature N₂ adsorption, TEM, XRD, XPS and etc. We studied the influence of synthesis conditions on the aerogels' structure, such as reactant mass percent, catalyst concentration, carbonization process and supersonic.Organic and carbon aerogel powder was prepared by sol-gel method with the help of ultrasonic emulsification technology using resorcinol and formaldehyde. Different experimental conditions were investigated to reveal the formation mechanism of aerogel powder. The particle-diameter distributions were measured by zetasizer, and the aerogel powder has been checked with low-temperature N₂ adsorption, TEM, XRD and etc. Optimize the conduction of experiment by research the influence of supersonic field, the mass percentage, temperature, time and the ratio of volume to dispersant and reactive liquid.The porous properties of carbonized aerogels and carbonized aerogels powders are characterized by low temperature N₂ adsorption method using surface area and pore size analyzer. The investigation is emphasized on the specific surface area, pore volume, average pore size and pore size distribution. The rules of the mesopores and micropores are obtained through Barrett-Joyner-Halenda(BJH) and Dollimore-Heal (DH) thermodynamic method. And the microscopic transformation rule of the pore structure is discussed by employing the Density Functional Theory (DFT).