Impervious Graphite vs Isostatic Graphite
Ceramic · grade comparison
Impervious Graphite and Isostatic Graphite are both ceramic grades. Isostatic Graphite is the stronger of the two: tensile strength 27 MPa (3.92 ksi) against 25 MPa (3.63 ksi) for Impervious Graphite, about 8% more. Impervious Graphite is stiffer (12 GPa vs 11 GPa) and Isostatic Graphite runs hotter in service (450°C vs 170°C continuous). On the shop floor, Isostatic Graphite machines more easily (excellent vs very good).
Isostatic GraphiteChoose it when strength drives the design, or when the part sees heat.
Impervious Graphite vs Isostatic 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 GraphiteIsostatic Graphite
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Flexural Strength
Shear Strength
Fracture Toughness (K_IC)
Hardness, Vickers
Hardness, Mohs
Shear Modulus
Bulk Modulus
Physical
Density and transition temperatures.
Density
Porosity
Melting Point (Solidus)
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Specific Heat Capacity 710 J/kg·K0.17 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 4.5 µm/m·K2.5 µin/in·°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
Same in both: Polishability 45 / 100 · Sintering / Firing Temperature 2,800°C5,072 °F
Sustainability
Primary-production footprint per kilogram.
Embodied Carbon (primary production)
Typical Recycled Content
Embodied Water
Same in both: Embodied Energy (primary production) 190 MJ/kg81,685 BTU/lb
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 | Isostatic Graphite |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Impervious Graphite vs Isostatic Graphite — frequently asked
Is Isostatic Graphite stronger than Impervious Graphite?
Yes. Isostatic Graphite has a typical tensile strength of 27 MPa (3.92 ksi) against 25 MPa (3.63 ksi) for Impervious Graphite — about 8% more.
Which is cheaper, Impervious Graphite or Isostatic Graphite?
Both sit in the same relative cost tier ($$$$, 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 Isostatic Graphite?
Isostatic 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 Impervious Graphite and Isostatic 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.