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Cordierite vs Synthetic Sapphire

Ceramic · grade comparison

Cordierite and Synthetic Sapphire are both ceramic grades. Synthetic Sapphire is the stronger of the two: tensile strength 400 MPa (58 ksi) against 25 MPa (3.63 ksi) for Cordierite, about 16 times as much. Synthetic Sapphire is harder — 2,000 HV against 700 HV for Cordierite — which matters for wear surfaces and threads. Cordierite is lighter (2.3 g/cm³ vs 3.98 g/cm³ for Synthetic Sapphire) and Synthetic Sapphire is stiffer (400 GPa vs 70 GPa). On the shop floor, Cordierite machines more easily (poor vs not recommended).

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

Synthetic SapphireChoose it when strength drives the design, or when surface hardness matters.

Cordierite vs Synthetic Sapphire: properties

CordieriteSynthetic Sapphire

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

70 GPa10.2 Msi
400 GPa58 Msi

Shear Modulus

28 GPa4.1 Msi
165 GPa23.9 Msi

Bulk Modulus

47 GPa6.8 Msi
250 GPa36.3 Msi

Poisson's Ratio

0.25
0.28

Tensile Strength (Ultimate)

25 MPa3.6 ksi
400 MPa58 ksi

Compressive Strength

350 MPa50.8 ksi
2,000 MPa290 ksi

Flexural Strength

70 MPa10.2 ksi
700 MPa102 ksi

Fracture Toughness (K_IC)

1.5 MPa·√m1.4 ksi·√in
2.5 MPa·√m2.3 ksi·√in

Hardness, Vickers

700 HV
2,000 HV

Hardness, Mohs

7
9

Shear Strength

—
480 MPa69.6 ksi

Hardness, Knoop

—
1,900 HK

Physical

Density and transition temperatures.

Density

2.3 g/cm³0.08 lb/in³
3.98 g/cm³0.14 lb/in³

Melting Point (Solidus)

1,465°C2,669 °F
2,053°C3,727 °F

Porosity

8%
0%

Refractive Index

—
1.768

Light Transmission

—
86%

Thermal

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

Thermal Conductivity

2.5 W/m·K1.4 BTU/hr·ft·°F
35 W/m·K20.2 BTU/hr·ft·°F

Specific Heat Capacity

800 J/kg·K0.19 BTU/lb·°F
760 J/kg·K0.18 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

2 µm/m·K1.1 µin/in·°F
5.6 µm/m·K3.1 µin/in·°F

Max Service Temperature (continuous)

1,250°C2,282 °F
1,600°C2,912 °F

Min Service Temperature

-200°C-328 °F
-269°C-452 °F

Electrical

Conductivity and insulation.

Electrical Resistivity

1×10¹¹ Ω·m3.94×10¹⁸ µΩ·in
1×10¹⁴ Ω·m3.94×10²¹ µΩ·in

Dielectric Strength

10 kV/mm254 V/mil
48 kV/mm1,219 V/mil

Dielectric Constant (1 MHz)

5
9.4

Dissipation Factor (1 MHz)

0.004
1×10⁻⁴

Volume Resistivity

1×10¹³ Ω·cm
1×10¹⁶ Ω·cm

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

70 / 100
96 / 100

Manufacturability

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

Machinability

20 / 100
4 / 100

Polishability

35 / 100
98 / 100

Sintering / Firing Temperature

1,350°C2,462 °F
2,100°C3,812 °F

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

30 MJ/kg12,898 BTU/lb
950 MJ/kg408,427 BTU/lb

Embodied Carbon (primary production)

2.2 kg CO₂/kg
60 kg CO₂/kg

Embodied Water

20 L/kg2.4 gal/lb
400 L/kg47.9 gal/lb

Same in both: Typical Recycled Content 5%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

11 kN·m/kg
101 kN·m/kg

Specific Stiffness (E / density)

30.4 MN·m/kg
100.5 MN·m/kg

Thermal Diffusivity

1.4 mm²/s
11.6 mm²/s

Thermal Shock Resistance Index

0
6

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 scaleCordierite

Manufacturing and finishing

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

Cordierite vs Synthetic Sapphire — frequently asked

Is Synthetic Sapphire stronger than Cordierite?

Yes. Synthetic Sapphire has a typical tensile strength of 400 MPa (58 ksi) against 25 MPa (3.63 ksi) for Cordierite — about 16 times as much.

Which is cheaper, Cordierite or Synthetic Sapphire?

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, Cordierite or Synthetic Sapphire?

Cordierite. Its machinability rates poor (20/100) against not recommended (4/100) for Synthetic Sapphire.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Cordierite and Synthetic Sapphire 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.