Amorphous Graphite vs Glassy Carbon
Ceramic · grade comparison
Amorphous Graphite and Glassy Carbon are both ceramic grades. Glassy Carbon is the stronger of the two: tensile strength 130 MPa (18.9 ksi) against 5 MPa (0.725 ksi) for Amorphous Graphite, about 26 times as much. Glassy Carbon is the more ductile: elongation 0.4% versus 0.2% for Amorphous Graphite, and Glassy Carbon is harder (340 HV vs 15 HV). Glassy Carbon is lighter (1.42 g/cm³ vs 2.25 g/cm³ for Amorphous Graphite) and Glassy Carbon is stiffer (35 GPa vs 7 GPa). On the shop floor, Amorphous Graphite machines more easily (excellent vs not recommended) and Amorphous Graphite sits in a lower cost tier (budget, $) than Glassy Carbon (high, $$$$).
Amorphous GraphiteChoose it when the part is machined in volume, or when cost is the deciding factor.
Glassy CarbonChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
Amorphous Graphite vs Glassy Carbon: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all ceramic 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 ceramic 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.
Amorphous GraphiteGlassy Carbon
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Flexural Strength
Shear Strength
Hardness, Vickers
Hardness, Mohs
Shear Modulus
Bulk Modulus
Poisson's Ratio
Hardness, Knoop
Same in both: Fracture Toughness (K_IC) 0.8 MPa·√m0.73 ksi·√in
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Porosity
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 710 J/kg·K0.17 BTU/lb·°F
Electrical
Conductivity and insulation.
Electrical Resistivity
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
Sintering / Firing Temperature
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 ceramic grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Amorphous Graphite | Glassy Carbon |
|---|---|---|
| Default condition | — | — |
| Relative cost | $ Budget | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Amorphous Graphite vs Glassy Carbon — frequently asked
Is Glassy Carbon stronger than Amorphous Graphite?
Yes. Glassy Carbon has a typical tensile strength of 130 MPa (18.9 ksi) against 5 MPa (0.725 ksi) for Amorphous Graphite — about 26 times as much.
Which is cheaper, Amorphous Graphite or Glassy Carbon?
Amorphous Graphite is the lower-cost material: it sits in the budget tier ($) while Glassy Carbon is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, Amorphous Graphite or Glassy Carbon?
Amorphous Graphite. Its machinability rates excellent (90/100) against not recommended (12/100) for Glassy Carbon.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Amorphous Graphite and Glassy Carbon 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.