Working With Silica Aerogels
The first thing most people do when they touch a piece of silica aerogel for the first time is shatter it into a million pieces. You may hear statements in the media like-"A new Space-Age material that will support up to 1000 times its own weight..." This may be true, but it is important to remember that since silica aerogel is a very low density material, "1000 times its own weight" isn't very much weight at all. Also, remember that silica aerogel is just another form of glass. If aerogel is handled roughly, it will break just like glass. However, if care is taken, the material can be handled and shaped effectively. A few pointers:
- Don't try to pick up large pieces by the corners. Slide a thin sheet of metal, or other stiff material, under the aerogel and use this to move the piece.
- Silica aerogel is much more durable if it is under compression. This is simply accomplished by vacuum-sealing the aerogel in a plastic bag (a typical food sealer works well for this). This method is very useful for shipping samples.
- Silica aerogel is best cut using a diamond coated saw, similar to the type used by gem and stone cutters. The most difficult problem here is holding the piece steady. A vacuum chuck works well for this.
- Most silica aerogel is destroyed by contact with liquids. However, it can be protected from damage by water (see the section on Surface Chemistry).
- Rapid changes in ambient pressure can cause the aerogel to shatter as gases try to enter or escape the pore network. Use care when placing aerogels under high vacuum.
Many people ask if there are any hazards associated with handling silica aerogel. Working with aerogel with your bare hands can have a slight desiccating effect on the skin. This is due to the absorbance of moisture and oils from the skin into the pores of the aerogel. This is more of a nuisance than a hazard and can be avoided by wearing gloves. Cutting and shaping aerogels usually produces a cloud of fine dust. The particles of aerogel in the dust are smooth and round and, therefore, are not considered to be a laceration hazard (as asbestos is). Nevertheless, it is a good precaution to work in a fume hood or wear a good respirator to avoid inhalation of the aerogel dust.
Go to the Table of Physical Properties