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Impervious Graphite vs Nuclear Graphite

Ceramic · grade comparison

Impervious Graphite and Nuclear Graphite are both ceramic grades. Impervious Graphite is stiffer (12 GPa vs 9.8 GPa) and Nuclear Graphite runs hotter in service (2,500°C vs 170°C continuous). On the shop floor, Nuclear Graphite machines more easily (excellent vs very good).

Nuclear GraphiteChoose it when the part sees heat, or when the part is machined in volume.

Impervious Graphite vs Nuclear Graphite: properties

Impervious GraphiteNuclear Graphite

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

12 GPa1.7 Msi
9.8 GPa1.4 Msi

Poisson's Ratio

0.2
0.14

Elongation at Break

0.3%
—

Compressive Strength

95 MPa13.8 ksi
78 MPa11.3 ksi

Flexural Strength

50 MPa7.3 ksi
39 MPa5.7 ksi

Shear Strength

18 MPa2.6 ksi
22 MPa3.2 ksi

Fracture Toughness (K_IC)

1.2 MPa·√m1.1 ksi·√in
0.9 MPa·√m0.82 ksi·√in

Hardness, Vickers

50 HV
—

Hardness, Mohs

2
1.5

Shear Modulus

—
4.4 GPa0.64 Msi

Bulk Modulus

—
5 GPa0.67 Msi

Same in both: Tensile Strength (Ultimate) 25 MPa3.6 ksi

Physical

Density and transition temperatures.

Density

1.8 g/cm³0.07 lb/in³
1.78 g/cm³0.06 lb/in³

Porosity

0.5%
20%

Melting Point (Solidus)

—
3,650°C6,602 °F

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

125 W/m·K72.2 BTU/hr·ft·°F
120 W/m·K69.3 BTU/hr·ft·°F

Max Service Temperature (continuous)

170°C338 °F
2,500°C4,532 °F

Min Service Temperature

-50°C-58 °F
-200°C-328 °F

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

1.2×10⁻⁵ Ω·m472 µΩ·in
1.1×10⁻⁵ Ω·m433 µΩ·in

Volume Resistivity

0 Ω·cm
0 Ω·cm

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

88 / 100
75 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

80 / 100
93 / 100

Polishability

45 / 100
35 / 100

Sintering / Firing Temperature

2,800°C5,072 °F
2,900°C5,252 °F

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

190 MJ/kg81,685 BTU/lb
180 MJ/kg77,386 BTU/lb

Embodied Water

—
60 L/kg7.2 gal/lb

Same in both: Embodied Carbon (primary production) 14 kg CO₂/kg · Typical Recycled Content 0%

Common Calculations

Ratios derived from the values above.

Specific Stiffness (E / density)

6.7 MN·m/kg
5.5 MN·m/kg

Thermal Diffusivity

97.8 mm²/s
95 mm²/s

Thermal Shock Resistance Index

58
68

Same in both: Specific Strength (UTS / density) 14 kN·m/kg

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.

501002005001,000234567Density (g/cm³)Yield strength (MPa) — log scale

Manufacturing and finishing

CapabilityImpervious GraphiteNuclear Graphite
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Impervious Graphite vs Nuclear Graphite — frequently asked

What is the difference between Impervious Graphite and Nuclear Graphite?

Impervious Graphite and Nuclear Graphite are both ceramic grades. Impervious Graphite is stiffer (12 GPa vs 9.8 GPa) and Nuclear Graphite runs hotter in service (2,500°C vs 170°C continuous). On the shop floor, Nuclear Graphite machines more easily (excellent vs very good).

Which is cheaper, Impervious Graphite or Nuclear 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 Nuclear Graphite?

Nuclear Graphite. Its machinability rates excellent (93/100) 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 Nuclear 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.