Abstract
This article will address autoclave design considerations andmanufacturing working with high pressure low temperaturesupercritical drying technique to produce silica aerogel. The designelects carbon dioxide as a supercritical fluid (31.7 oC and 72.3 bar).Both temperature and pressure have independently controllingfacility through present design. The autoclave was light weight (4.5kg) and factory-made from stainless steel. It contains a high pressurewindow for monitoring both transfer carbon dioxide gas to liquidcarbon dioxide and watching supercritical drying via aerogelpreparation process. In this work aerogel samples were prepared andthe true apparent densities, total pore volume and pore sizedistribution, BET surface area, spectroscopic refractive index,structure and thermal properties have been systematicallyinvestigated characteristic.
Highlights
Since last decades, autoclaves are used in many variety fields; scientific, medical and industry
Aerogel can be created by combining each of a polymer with solvent to forming the gel, the liquid inside the pores of gel will be removing and replacing by air. silica aerogels are highly porous and very light materials that are intriguingly and complexly networked with high specific surface area, low refractive index, low thermal conductivity and low dielectric constant with many fascinating of optical properties all these features make the aerogel ideal choice for different applications
During the initial stages of the supercritical CO2 drying process the diffusion kinetics is the another important factor of the liquid CO2 – solvent exchange in the autoclave. unsteady-state diffusion of solvent and liquid CO2 will cause the structural damage at this point, which occurs when liquid CO2 and the solvent mixture is below the binary critical curve where both liquids are not miscible and exist as two separate phases
Summary
Autoclaves are used in many variety fields; scientific, medical and industry. Our autoclave design will have used to produce silica aerogel material through sol-gel technique by supercritical drying method. Silica aerogels are highly porous and very light materials that are intriguingly and complexly networked with high specific surface area, low refractive index, low thermal conductivity and low dielectric constant with many fascinating of optical properties all these features make the aerogel ideal choice for different applications. In the early 1930, Aerogels were first made by Samuel He dried his waterglass-derived silica gels, employing a solvent exchange and using supercritical conditions to remove the pore fluid (methanol) nondestructively [5]. In our work producing aerogel hydrophilic by using low temperature supercritical drying with co gas (LTSCD). When the liquid starts to evaporate from the gel, surface tension creates concave menisci, with continuously of liquid evaporation the compressive forces build up around the perimeter of the pore and contrast. Through heating and compressing the sol-gel above the critical temperature and pressure of the solvent will eliminate the solvent from the sol-gel without generating a two-
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