Analysis and characterization of etched silica aerogels

Silica aerogels are unique materials with characteristics that allow them to be used in a wide variety of applications. They are nanoporous, with low density, large surface area, low thermal conductivity, and they are relatively translucent. Recently, the use of a CO2 engraving and cutting system to etch a variety of patterns, including text and photographs, onto the surface of silica aerogel with minimal damage to the bulk aerogel was demonstrated; however, the mechanism by which the aerogel surface is altered was not understood and the extent of the damage not quantified. In this paper we present results on the effect of etching on, and cutting through, silica aerogel material with a CO2 laser engraving and cutting system, using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and gas adsorption analysis. SEM analyses of the etched aerogel material show evidence of melting. Surface areas of the etched portion of aerogel monoliths are lower compared that the unetched material while pore diameters are larger. FTIR shows that little structural change occurs on the molecular level during etching of the silica aerogel.