Alpha-Quartz vs Fused Silica
Glass · grade comparison
Alpha-Quartz and Fused Silica are both glass grades. Alpha-Quartz is the stronger of the two: tensile strength 55 MPa (7.98 ksi) against 50 MPa (7.25 ksi) for Fused Silica, about 10% more. Alpha-Quartz is harder — 1,150 HV against 700 HV for Fused Silica — which matters for wear surfaces and threads. Fused Silica is lighter (2.2 g/cm³ vs 2.65 g/cm³ for Alpha-Quartz) and Alpha-Quartz is stiffer (87 GPa vs 72 GPa). On the shop floor, Fused Silica sits in a lower cost tier (standard, $$) than Alpha-Quartz (high, $$$$).
Alpha-QuartzChoose it when strength drives the design, or when surface hardness matters.
Fused SilicaChoose it when weight is the constraint, or when the part sees heat.
Alpha-Quartz vs Fused Silica: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all glass grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all glass grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Bulk Modulus
Tensile Strength (Ultimate)
Compressive Strength
Flexural Strength
Shear Strength
Fracture Toughness (K_IC)
Hardness, Vickers
Hardness, Knoop
Hardness, Mohs
Same in both: Shear Modulus 31 GPa4.5 Msi · Poisson's Ratio 0.17 · Elongation at Break 0%
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Refractive Index
Same in both: Light Transmission 92% · Porosity 0%
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Specific Heat Capacity 740 J/kg·K0.18 BTU/lb·°F
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Diffusivity
Thermal Shock Resistance Index
Strength versus weight
Yield strength against density for every glass grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Alpha-Quartz | Fused Silica |
|---|---|---|
| Default condition | — | Annealed Glass |
| Relative cost | $$$$ High | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Alpha-Quartz vs Fused Silica — frequently asked
Is Alpha-Quartz stronger than Fused Silica?
Yes. Alpha-Quartz has a typical tensile strength of 55 MPa (7.98 ksi) against 50 MPa (7.25 ksi) for Fused Silica — about 10% more.
Which is cheaper, Alpha-Quartz or Fused Silica?
Fused Silica is the lower-cost material: it sits in the standard tier ($$) while Alpha-Quartz is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose Alpha-Quartz over Fused Silica?
Pick Alpha-Quartz when strength drives the design, or when surface hardness matters. Pick Fused Silica when weight is the constraint, or when the part sees heat.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Alpha-Quartz and Fused Silica side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.