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Graphite vs SSiC

Ceramic · grade comparison

Graphite and SSiC are both ceramic grades. SSiC is the stronger of the two: tensile strength 260 MPa (37.7 ksi) against 30 MPa (4.35 ksi) for Graphite, about 8.7 times as much. Graphite is lighter (1.78 g/cm³ vs 3.12 g/cm³ for SSiC) and SSiC is stiffer (410 GPa vs 11 GPa). On the shop floor, Graphite machines more easily (excellent vs not recommended).

GraphiteChoose it when weight is the constraint, or when the part is machined in volume.

SSiCChoose it when strength drives the design, or when the part sees heat.

Graphite vs SSiC: properties

GraphiteSSiC

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

11 GPa1.6 Msi
410 GPa59.5 Msi

Shear Modulus

4.5 GPa0.65 Msi
175 GPa25.4 Msi

Bulk Modulus

7 GPa0.94 Msi
205 GPa29.7 Msi

Poisson's Ratio

0.2
0.16

Tensile Strength (Ultimate)

30 MPa4.4 ksi
260 MPa37.7 ksi

Compressive Strength

90 MPa13.1 ksi
2,800 MPa406 ksi

Flexural Strength

50 MPa7.3 ksi
410 MPa59.5 ksi

Shear Strength

28 MPa4.1 ksi
—

Fracture Toughness (K_IC)

1 MPa·√m0.91 ksi·√in
3.5 MPa·√m3.2 ksi·√in

Hardness, Mohs

1.5
9.5

Hardness, Vickers

—
2,500 HV

Hardness, Knoop

—
2,400 HK

Physical

Density and transition temperatures.

Density

1.78 g/cm³0.06 lb/in³
3.12 g/cm³0.11 lb/in³

Melting Point (Solidus)

3,650°C6,602 °F
2,700°C4,892 °F

Porosity

12%
1%

Thermal

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

Thermal Conductivity

110 W/m·K63.6 BTU/hr·ft·°F
120 W/m·K69.3 BTU/hr·ft·°F

Specific Heat Capacity

710 J/kg·K0.17 BTU/lb·°F
700 J/kg·K0.17 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

4.5 µm/m·K2.5 µin/in·°F
4 µm/m·K2.2 µin/in·°F

Max Service Temperature (continuous)

450°C842 °F
1,600°C2,912 °F

Same in both: Min Service Temperature -200°C-328 °F

Electrical

Conductivity and insulation.

Electrical Resistivity

1.1×10⁻⁵ Ω·m433 µΩ·in
100 Ω·m3.94×10⁹ µΩ·in

Volume Resistivity

0 Ω·cm
10,000 Ω·cm

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

80 / 100
97 / 100

Manufacturability

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

Machinability

92 / 100
5 / 100

Polishability

35 / 100
92 / 100

Sintering / Firing Temperature

2,900°C5,252 °F
2,100°C3,812 °F

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

120 MJ/kg51,591 BTU/lb
110 MJ/kg47,292 BTU/lb

Embodied Carbon (primary production)

9 kg CO₂/kg
8 kg CO₂/kg

Embodied Water

90 L/kg10.8 gal/lb
200 L/kg24 gal/lb

Typical Recycled Content

10%
5%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

17 kN·m/kg
83 kN·m/kg

Specific Stiffness (E / density)

6.2 MN·m/kg
131.4 MN·m/kg

Thermal Diffusivity

87 mm²/s
54.9 mm²/s

Thermal Shock Resistance Index

67
19

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

CapabilityGraphiteSSiC
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Graphite vs SSiC — frequently asked

Is SSiC stronger than Graphite?

Yes. SSiC has a typical tensile strength of 260 MPa (37.7 ksi) against 30 MPa (4.35 ksi) for Graphite — about 8.7 times as much.

Which is cheaper, Graphite or SSiC?

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, Graphite or SSiC?

Graphite. Its machinability rates excellent (92/100) against not recommended (5/100) for SSiC.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Graphite and SSiC 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.