Minerals > Fused Silica, SiO2
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Fused silica is a noncrystalline (glass) form of silicon dioxide (quartz, sand). Typical of glasses, it lacks long range order in its atomic structure. It’s highly cross linked three dimensional structure gives rise to it’s high use temperature and low thermal expansion coefficient. Key Properties
Typical Uses
General Information
The glass has very high viscosity, and this property allows the glass to be formed, cooled and annealed without crystallizing. Fused silica glass is a very low thermal expansion material, and so is extremely thermal shock resistant. The material is also chemically inert up to moderate temperatures except to hydrofluoric acid, which dissolves silica. It will devitrify above about 1100°C in the presence of contaminants such as sodium, phosphorus and vanadium, with the formation of cristobalite crystals which destroy the properties of the glass. The dielectric properties are stable up through gigahertz frequencies. Engineering Properties*Fused Silica |
High
purity sand deposits provide the raw material for bulk refractory grade,
which is electric arc melted at extremely high temperatures. Optical and
general purpose fused silica rods and tubing are drawn from a melt made
from high purity chemicals. Fiber optic purity is made by thermal
decomposition of high purity gaseous silica containing chemicals. The
glass may be clear or translucent, in which case it is often referred to
as fused quartz.| Mechanical | Units of Measure | SI/Metric | (Imperial) |
| Density | gm/cc (lb/ft3) | 2.2 | (137.4) |
| Porosity | % (%) | 0 | 0 |
| Color | ----------- | clear | ----------- |
| Flexural Strength | MPa (lb/in2x103) | ----------- | ----------- |
| Elastic Modulus | GPa (lb/in2x106) | 73 | (10.6) |
| Shear Modulus | GPa (lb/in2x106) | 31 | (4.5) |
| Bulk Modulus | GPa (lb/in2x106) | 41 | (6) |
| Poisson’s Ratio | ----------- | 0.17 | (0.17) |
| Compressive Strength | MPa (lb/in2x103) | 1108 | (160.7) |
| Hardness | Kg/mm2 | 600 | ----------- |
| Fracture Toughness KIC | MPa•m1/2 | ----------- | ----------- |
| Maximum Use Temperature (no load) | °C (°F) | 1100 | (2000) |
Thermal
| Mechanical | Units of Measure | SI/Metric | (Imperial) |
| Thermal Conductivity | W/m•°K (BTU•in/ft2•hr•°F) | 1.38 | (9.6) |
| Coefficient of Thermal Expansion | 10–6/°C (10–6/°F) | 0.55 | (.31) |
| Specific Heat | J/Kg•°K (Btu/lb•°F) | 740 | (0.18) |
Electrical
| Mechanical | Units of Measure | SI/Metric | (Imperial) |
| Dielectric Strength | ac-kv/mm (volts/mil) | 30 | (750) |
| Dielectric Constant | @ 1 MHz | 3.82 | (3.82) |
| Dissipation Factor | @ 1 MHz | 0.00002 | (0.00002) |
| Loss Tangent | @ 1 MHz | ——— | ——— |
| Volume Resistivity | ohm•cm | >1010 | ——— |
*All properties are room temperature values except as noted.
The data presented is typical of commercially available material and
is offered for comparative purposes only. The information is not to be
interpreted as absolute material properties nor does it constitute a
representation or warranty for which we assume legal liability. User
shall determine suitability of the material for the intended use and
assumes all risk and liability whatsoever in connection therewith.