Fused Silica · grade
Fused Silica Opaque
Properties of the Opaque condition, compared with the other Fused Silica tempers.
Use for furnace liners, diffusion-furnace ware and heat shields where IR opacity and low cost matter more than optical clarity.
What is Fused Silica Opaque?
Fused Silica Opaque is Fused Silica in the Opaque grade — use for furnace liners, diffusion-furnace ware and heat shields where IR opacity and low cost matter more than optical clarity. Fused Silica Opaque has a tensile strength of 50 MPa (7.25 ksi), stronger than 57% of glass grades. Elongation at break is 0% and the elastic modulus is 62 GPa (8.99 Msi). Fused Silica Opaque has a density of 2.05 g/cm³ (0.0741 lb/in³), lighter than 98% of glass grades. It melts at 1,713°C (3,115 °F). Annealed Glass is the default condition FabDigit quotes; Opaque is available on request or by drawing note.
Advantages
- Lightweight — 2.05 g/cm³ (0.0741 lb/in³), better than 98% of glass grades
- High service temperature — 1,150°C (2,102 °F), better than 90% of glass grades
- Good corrosion resistance — 95/100, better than 90% of glass grades
Limitations
- Low stiffness — 62 GPa (8.99 Msi), worse than 78% of glass grades
Fused Silica Opaque properties
Typical room-temperature values for Fused Silica Opaque — 8 properties are specific to this condition; the rest are grade-level values shared by every Fused Silica temper. Each bar shows where the value sits among the glass grades in FabDigit's library — further right is higher.
Physical5
Fused Silica Opaque has a density of 2.05 g/cm³ (0.0741 lb/in³), lighter than 98% of glass grades. It melts at 1,713°C (3,115 °F).
Mechanical12
Fused Silica Opaque has a tensile strength of 50 MPa (7.25 ksi), stronger than 57% of glass grades. Elongation at break is 0% and the elastic modulus is 62 GPa (8.99 Msi).
Thermal5
Fused Silica Opaque is rated for continuous service to 1,150°C (2,102 °F). It conducts heat at 1.1 W/m·K (0.636 BTU/hr·ft·°F), worse than 70% of glass grades. Thermal expansion is 0.55 µm/m·K (0.306 µin/in·°F).
Electrical5
Fused Silica Opaque 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 90% of glass grades.
Sustainability4
Producing a kilogram of Fused Silica Opaque takes about 55 MJ of energy and emits 4 kg of CO₂ — less than 52% of glass grades. Typical recycled content is 0%.
Manufacturability2
Fused Silica Opaque's machinability is not recommended (10/100, worse than 76% of glass grades).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Fused Silica tempers and conditions
Fused Silica is also supplied in 4 other conditions. The full side-by-side table is on the Fused Silica overview.
- Annealed GlassDefaultDefault choice for windows, tubes, crucibles and fixtures where low CTE and thermal shock resistance matter and stress birefringence is not critical.700 HV
- JGS1Pick 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 MPa tensile
- OpaqueUse for furnace liners, diffusion-furnace ware and heat shields where IR opacity and low cost matter more than optical clarity.8 properties
Working with Fused Silica Opaque
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.
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.
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) | — |
Fused Silica Opaque — frequently asked
What is Fused Silica Opaque used for?
Fused Silica Opaque 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 Opaque?
Fused Silica Opaque has a typical tensile strength of 50 MPa (7.25 ksi) — stronger than 57% of glass grades. Strength varies by condition: see the 5 listed tempers.
Is Fused Silica Opaque easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 76% 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 Opaque 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 Opaque?
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 Opaque 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 Opaque?
Fused Silica Opaque is rated for continuous use to about 1,150°C (2,102 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in Fused Silica Opaque?
Yes — Fused Silica Opaque is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.