Amorphous Graphite vs Impervious Graphite
Ceramic · grade comparison
Amorphous Graphite and Impervious Graphite are both ceramic grades. Impervious Graphite is the stronger of the two: tensile strength 25 MPa (3.63 ksi) against 5 MPa (0.725 ksi) for Amorphous Graphite, about 5.0 times as much. Impervious Graphite is the more ductile: elongation 0.3% versus 0.2% for Amorphous Graphite, and Impervious Graphite is harder (50 HV vs 15 HV). Impervious Graphite is lighter (1.8 g/cm³ vs 2.25 g/cm³ for Amorphous Graphite) and Impervious Graphite is stiffer (12 GPa vs 7 GPa). On the shop floor, Amorphous Graphite machines more easily (excellent vs very good) and Amorphous Graphite sits in a lower cost tier (budget, $) than Impervious Graphite (high, $$$$).
Amorphous GraphiteChoose it when the part sees heat, or when the part is machined in volume.
Impervious GraphiteChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
Amorphous Graphite vs Impervious Graphite: 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 GraphiteImpervious Graphite
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
Fracture Toughness (K_IC)
Hardness, Vickers
Hardness, Mohs
Poisson's Ratio
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 | Impervious Graphite |
|---|---|---|
| Default condition | — | — |
| Relative cost | $ Budget | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Amorphous Graphite vs Impervious Graphite — frequently asked
Is Impervious Graphite stronger than Amorphous Graphite?
Yes. Impervious Graphite has a typical tensile strength of 25 MPa (3.63 ksi) against 5 MPa (0.725 ksi) for Amorphous Graphite — about 5.0 times as much.
Which is cheaper, Amorphous Graphite or Impervious Graphite?
Amorphous Graphite is the lower-cost material: it sits in the budget tier ($) while Impervious Graphite is high ($$$$). 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 Impervious Graphite?
Amorphous Graphite. Its machinability rates excellent (90/100) against very good (80/100) for Impervious Graphite.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Amorphous Graphite and Impervious Graphite 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.