Impervious Graphite vs Pyrolytic Graphite
Ceramic · grade comparison
Impervious Graphite and Pyrolytic Graphite are both ceramic grades. Pyrolytic Graphite is the stronger of the two: tensile strength 100 MPa (14.5 ksi) against 25 MPa (3.63 ksi) for Impervious Graphite, about 4.0 times as much. Impervious Graphite is lighter (1.8 g/cm³ vs 2.2 g/cm³ for Pyrolytic Graphite) and Pyrolytic Graphite is stiffer (30 GPa vs 12 GPa). On the shop floor, Impervious Graphite machines more easily (very good vs good).
Impervious GraphiteChoose it when weight is the constraint, or when the part is machined in volume.
Pyrolytic GraphiteChoose it when strength drives the design, or when the part sees heat.
Impervious Graphite vs Pyrolytic 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.
Impervious GraphitePyrolytic Graphite
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Compressive Strength
Flexural Strength
Shear Strength
Fracture Toughness (K_IC)
Hardness, Vickers
Hardness, Mohs
Shear Modulus
Bulk Modulus
Same in both: Elongation at Break 0.3%
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Same in both: Porosity 0.5%
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)
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 | Impervious Graphite | Pyrolytic Graphite |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Impervious Graphite vs Pyrolytic Graphite — frequently asked
Is Pyrolytic Graphite stronger than Impervious Graphite?
Yes. Pyrolytic Graphite has a typical tensile strength of 100 MPa (14.5 ksi) against 25 MPa (3.63 ksi) for Impervious Graphite — about 4.0 times as much.
Which is cheaper, Impervious Graphite or Pyrolytic Graphite?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Impervious Graphite or Pyrolytic Graphite?
Impervious Graphite. Its machinability rates very good (80/100) against good (55/100) for Pyrolytic Graphite.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Impervious Graphite and Pyrolytic 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.