Fused Silica
GB JGS1/JGS2 · also Quartz Glass, GE 124
Fused Silica is amorphous vitreous silica (grades GE 124, Suprasil, Spectrosil, JGS1/JGS2/JGS3 and opaque) combining excellent UV-VIS-NIR transmission with very low thermal expansion.
Reference datasheet — Fused Silica is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Annealed Glass condition
Fused Silica tempers and conditions
Fused Silica is supplied in 4 conditions, soft to hard. Annealed Glass is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed GlassDefault standard annealed fused silica (general optical/thermal grade) | Default choice for windows, tubes, crucibles and fixtures where low CTE and thermal shock resistance matter and stress birefringence is not critical. | 50 | 0 | 700 HV | 1 W/m·K | |
Synthetic/high-purity UV grade fused silica | Pick for deep-UV optics, excimer/UV lamp envelopes and photolithography windows; high OH content gives UV transmission but an OH absorption band near 2.7 µm. | 50 | 0 | 650 HV | 1 W/m·K | |
Optical grade fused quartz | Economical electrically fused optical grade for near-UV/visible windows, sight glasses and lamp tubes where deep-UV transmission is not required. | 50 | 0 | 700 HV | 1 W/m·K | |
Infrared grade, low-OH fused silica | Choose for IR windows and optics to ~3.5 µm and for high-temperature use, since low hydroxyl content removes the 2.7 µm water band and raises the viscosity/annealing point. | 50 | 0 | 700 HV | 1 W/m·K |
Supply forms, finishes and certifications
Ways Fused Silica is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Opaque | Sintered/bubble-filled opaque fused quartz | Grade option |
What is Fused Silica?
Fused Silica is amorphous vitreous silica (grades GE 124, Suprasil, Spectrosil, JGS1/JGS2/JGS3 and opaque) combining excellent UV-VIS-NIR transmission with very low thermal expansion. It is used where dimensional stability under thermal cycling and deep-UV transmission are both required, and is supplied as plate, blanks, tube, rod and formed labware to a service temperature of about 1100 °C. Grade choice matters: synthetic grades transmit further into the UV than fused quartz, cost is well above borosilicate, machinability is poor (score 10), and long soaks at high temperature cause devitrification. Borofloat 33 is the cheaper option when 450 °C service and 3.3 expansion are sufficient. Fused Silica has a density of 2.2 g/cm³ (0.0795 lb/in³), lighter than 94% of glass grades. It melts at 1,713°C (3,115 °F). Fused Silica has a tensile strength of 50 MPa (7.25 ksi), stronger than 59% of glass grades. Elongation at break is 0% and the elastic modulus is 72 GPa (10.4 Msi).
What is Fused Silica used for?
- Semiconductor wafer carriers and boats
- UV optics, windows and lenses
- Photomask and lithography substrates
- Optical fiber preforms
- Excimer laser optics
- Diffusion furnace tubes and bell jars
- Metrology and interferometer reference flats
Advantages
- Lightweight — 2.2 g/cm³ (0.0795 lb/in³), better than 94% of glass grades
- High service temperature — 1,100°C (2,012 °F), better than 92% of glass grades
- Good corrosion resistance — 95/100, better than 92% of glass grades
Fused Silica properties
Typical room-temperature values for Fused Silica-Annealed Glass; bars are the position among glass grades.
Physical5
Fused Silica has a density of 2.2 g/cm³ (0.0795 lb/in³), lighter than 94% of glass grades. It melts at 1,713°C (3,115 °F).
Mechanical13
Fused Silica has a tensile strength of 50 MPa (7.25 ksi), stronger than 59% of glass grades. Elongation at break is 0% and the elastic modulus is 72 GPa (10.4 Msi).
Thermal5
Fused Silica is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 1.4 W/m·K (0.797 BTU/hr·ft·°F), better than 54% of glass grades. Thermal expansion is 0.55 µm/m·K (0.306 µin/in·°F).
Electrical5
Fused Silica is an electrical insulator with a dielectric strength of 30 kV/mm (762 V/mil) and a resistivity of 1×10¹⁶ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (95/100), better than 92% of glass grades.
Sustainability4
Producing a kilogram of Fused Silica takes about 55 MJ of energy and emits 4 kg of CO₂ — more than 52% of glass grades. Typical recycled content is 0%.
Manufacturability2
Fused Silica's machinability is not recommended (10/100, worse than 80% of glass grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the glass family
Yield strength against density for every glass grade FabDigit runs. Fused Silica is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Fused Silica
Is Fused Silica easy to machine?
Diamond grinding, core drilling, ultrasonic and laser machining only; no conventional cutting — chipping at edges must be controlled by bevelling and coolant flood.
Can Fused Silica be welded?
Joined by oxy-hydrogen flame working or CO₂-laser fusion at ~1800 °C; joints must be flame- or furnace-annealed near 1100 °C to relieve stress.
Can Fused Silica be formed, bent or molded?
Hot formed by flame/lathe working above ~1700 °C (tubes, flanges, bulbs); slumping and mould pressing possible but devitrification limits soak time.
Fused Silica chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Alas Al2O3 impurity, ppm level in synthetic grades | ≤ 0.01 | 0 |
| Naalkali impurity | ≤ 0 | 2×10⁻⁴ |
| Fecontrols UV/visible absorption | ≤ 5×10⁻⁴ | 1×10⁻⁴ |
| OHhydroxyl: <5 ppm in IR/JGS3 grades, 200–1200 ppm in synthetic JGS1 | 2×10⁻⁵ – 0.12 | 0.02 |
| SiO2JGS2/JGS3 fused natural quartz ≥99.9 %; JGS1/synthetic ≥99.99 % | ≥ 99.9 (balance) |
What surface finishes work on Fused Silica?
Lapping and CeO₂/colloidal-silica polishing give sub-nanometre optical finishes; HF etching or fire-polishing removes subsurface damage, and AR or metallic coatings adhere well.
Equivalent designations
Standards and trade names that resolve to Fused Silica in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- GB (China)
- JGS1/JGS2
- Trade names
- Quartz GlassGE 124SuprasilSpectrosil
- Also called
- Fused QuartzUV Grade Fused Silica
- Other
- SiO2
How much does Fused Silica cost?
Fused Silica is a standard-cost glass ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Fused Silica — frequently asked
What is Fused Silica used for?
Fused Silica is typically used for semiconductor wafer carriers and boats, UV optics, windows and lenses, photomask and lithography substrates, optical fiber preforms, excimer laser optics and diffusion furnace tubes and bell jars. In short: pure synthetic silica.
What is the tensile strength of Fused Silica?
Fused Silica has a typical tensile strength of 50 MPa (7.25 ksi) — stronger than 59% of glass grades. Strength varies by condition: see the 4 listed tempers.
Is Fused Silica easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 80% of glass grades). Diamond grinding, core drilling, ultrasonic and laser machining only; no conventional cutting — chipping at edges must be controlled by bevelling and coolant flood.
Can Fused Silica be welded?
Joined by oxy-hydrogen flame working or CO₂-laser fusion at ~1800 °C; joints must be flame- or furnace-annealed near 1100 °C to relieve stress.
What surface finishes work on Fused Silica?
Lapping and CeO₂/colloidal-silica polishing give sub-nanometre optical finishes; HF etching or fire-polishing removes subsurface damage, and AR or metallic coatings adhere well.
Can Fused Silica be formed, bent or molded?
Hot formed by flame/lathe working above ~1700 °C (tubes, flanges, bulbs); slumping and mould pressing possible but devitrification limits soak time.
What is the maximum service temperature of Fused Silica?
Fused Silica is rated for continuous use to about 1,100°C (2,012 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Fused Silica cost?
Fused Silica is a standard-cost glass ($$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Quartz Glass for Optics — Data and Properties — Heraeus Conamic (2023)
- HPFS Fused Silica Standard Grade Datasheet — Corning (2022)
- Fused Quartz / Type 214 Properties — Momentive Technologies (2021)
- ASM Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- GB/T 26999 (JGS1/JGS2/JGS3) — SAC (2011)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.