DeutschWhat Is Fused Quartz?
Fused quartz is a glass consisting of almost pure silicon dioxide (SiO₂), produced by melting high-purity natural quartz crystal or sand at very high temperature. Unlike soda-lime or borosilicate glasses, it contains virtually no other oxides, which gives it a combination of properties no ordinary glass can match: extreme temperature resistance, near-zero thermal expansion, high chemical resistance and wide optical transmission.
Typical Properties of Fused Quartz
The values below are typical published values for commercially available fused quartz. Exact figures vary by grade and manufacturer.
| Property | Typical Value |
|---|---|
| SiO₂ purity | ≥ 99.9% (grade dependent) |
| Density | ≈ 2.2 g/cm³ |
| Softening point | ≈ 1665–1700 °C |
| Continuous use temperature | ≈ 1100–1200 °C |
| Coefficient of thermal expansion | ≈ 0.55 × 10⁻⁶ /K (20–300 °C) |
| Thermal shock resistance | Excellent — withstands rapid temperature changes |
| Transmission range | UV to IR, grade dependent (≈ 180–3500 nm) |
| Electrical insulation | High, stable at elevated temperature |
| Chemical resistance | Inert to most acids; attacked by HF and hot concentrated alkalis |
Why These Properties Matter
- Low thermal expansion means parts keep their dimensions through heating cycles and resist thermal shock — critical for furnace tubes and optical mounts.
- High purity prevents contamination of semiconductor and solar processes.
- Chemical inertness allows use with strong acids in laboratory and chemical applications (except hydrofluoric acid).
- UV transmission makes quartz the default choice for UV lamps, sterilization systems and UV optics.
How Fused Quartz Differs From Fused Silica
In common industry usage the two terms overlap heavily; strictly, "fused quartz" refers to glass fused from natural crystal, while "fused silica" refers to glass from synthetic or high-purity silica precursors. See our fused silica page for a detailed comparison.
Products Made From Fused Quartz
GKLQuartz fabricates quartz tubes, rods, plates, boats, crucibles, windows and sight glass from fused quartz grades including JGS1, JGS2 and JGS3 (grade comparison).
