3 Mechanical Design

3.5 Aerogel blocks

3.5.1 - Transmission of MEW Aerogel

We have tried four methods in order to cut aerogel. The Novosibirsk aerogel is less fragile than M.E.W. aerogel so it was possible to cut it by grinding[6]. However, the M.E.W. aerogel breaks very easily so it is impossible to cut it like that.

We have succeeded in cutting M.E.W. aerogel using three methods:

• Using a ceramic disc. Achieved a precision of mm. Time: approximately. 20 min/block. Contact: G.Andalo Srl, Imola, Italy

• Using a high speed rotating post. Achieved a precision of mm. Time: approximately. 20 min/block. Contact: Plastic Form S.A., Nea Santa, Greece.

• Using a high speed rotating disc of 0.2 mm cross-section.

Table 3-2 summarizes the physical properties of aerogel.

Physical Properties of Aerogel

Property	Value	Comments
Apparent density	0.125 gr/cm3
Index of refraction	1.0350-1.0366	Measured by Matsushita Electric Works Ltd.
Thermal Tolerance[3-2]	up to 500 °C	Melting point > 1200 °C
Thermal expansion Coefficient [3-2]	4.0x10-6	Determined using ultrasonic methods
Poisson's ratio [3-2]	0.2	Independent of density
Young's Modulus [3-2]	106-107 N/m2
Tensile Strength [3-2]	16 kPa	For density 0.1 gr/cm3
Fracture Toughness [3-2]	~0.8 kPa/m2	For density 0.1 gr/cm3. Determined by 3-point bending
Dielectric Constant [3-2]	1.1	For density 0.1 gr/cm3

Aerogels are known to be very good thermal insulators. The thermal conductivity actually decreases even more in vacuum. Typical aerogels have a total thermal conductivity of 0.017 W/mK.