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Atmospheric Drying Technology is Aerogel Powder Process Research Direction
2017-12-21 16:13:08       From: Tradematt-Aerogel

Atmospheric Drying Technology is Aerogel Powder Process Research Direction

At present, the preparation of silica aerogel powder usually includes sol-gel and dry two main processes, through the sol-gel process to obtain the required nano-holes and the corresponding gel skeleton. Due to the surface tension of the solvent inside the gel matrix, the skeleton will collapse under normal drying conditions. The core of the aerogel powder preparation technology is to prevent the collapse of the nano-pore structure caused by the capillary force during the drying process.
Aerogel is similar to making tofu, first of all to use raw materials made of soy milk, and then coagulation into tofu, tofu if the water squeezed out inside is tofu, into a substantial volume of dried tofu. Aerogel powder is similar to the tofu in the water to squeeze out, but the volume can not be reduced, it is necessary to add gas into it, so more difficult.

According to different processes, aerogel powder drying is mainly divided into supercritical drying process and atmospheric drying process two. Supercritical drying technology is the earliest to achieve batch preparation of aerogel technology, but also the current domestic and foreign aerogel enterprises to adopt more technology, through pressure and temperature control, the solvent in the drying process to reach its own critical point. The solvent in the supercritical state has no apparent surface tension, so that the gel can maintain the intact skeleton structure during the drying process, and remove the large amount of liquid in the coagulation under the premise of maintaining the original structure to obtain the aerogel.

Atmospheric pressure drying process is the principle of first choice of a low surface tension of solvent replacement wetting gel pores larger surface tension of water and alcohol, and then the hydrophobic surface of the gel modified so that the degree of gel contraction to a minimum; In addition, the effect of capillary pressure can be reduced by adjusting the uniformity of the gel pores and strengthening the network skeleton strength, so that the structure and properties of the aerogel prepared by the supercritical drying can be made to be similar under normal pressure.

Supercritical drying using high-pressure equipment, the general working pressure up to 7MPa ~ 20MPa, the early high investment, operation and maintenance costs are higher; atmospheric pressure drying technology using conventional atmospheric pressure equipment, because no high pressure conditions, the initial investment low, but technology The threshold is higher, the formula design and process optimization of the combination of higher requirements.

Experts believe that atmospheric drying is a new type of aerogel powder preparation process, is currently the most active research and development potential of the largest aerogel mass production technology.
Aerogel Powder Atmospheric Drying.jpg
Aerogel if you want to meet the huge market of building insulation, such as to achieve an annual output of 500,000 cubic meters of medium-sized, the use of supercritical drying technology equipment will be up to billions of dollars, is not conducive to aerogels bigger and stronger. The use of atmospheric drying technology, enterprises can invest less to achieve a larger scale of production, more able to adapt to the needs of future large-scale production.
In addition, limited by the silicon source, supercritical drying technology to reduce raw material costs limited space, only by optimizing the system to improve production efficiency; and atmospheric pressure drying on the acceptance of cheap silicon sources more powerful, there are more freedom of the process optimization, Thus having greater cost reduction space.

Atmospheric drying can be achieved by continuous automatic aerogel production efficiency can be increased by 3 to 5 times, product quality and stability and the level of production safety can be significantly improved.