Mullite vs Steatite
Ceramic · grade comparison
Mullite and Steatite are both ceramic grades. Mullite is the stronger of the two: tensile strength 80 MPa (11.6 ksi) against 60 MPa (8.7 ksi) for Steatite, about 33% more. Mullite is harder — 1,100 HV against 650 HV for Steatite — which matters for wear surfaces and threads. Steatite is lighter (2.8 g/cm³ vs 2.9 g/cm³ for Mullite) and Mullite is stiffer (150 GPa vs 100 GPa). On the shop floor, Mullite sits in a lower cost tier (premium, $$$) than Steatite (high, $$$$).
MulliteChoose it when strength drives the design, or when surface hardness matters.
SteatiteChoose it when weight is the constraint.
Mullite vs Steatite: 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.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Tensile Strength (Ultimate)
Flexural Strength
Shear Strength
Fracture Toughness (K_IC)
Hardness, Vickers
Hardness, Knoop
Hardness, Mohs
Same in both: Poisson's Ratio 0.25 · Elongation at Break 0% · Compressive Strength 700 MPa102 ksi
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Refractive Index
Porosity
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Same in both: Min Service Temperature -200°C-328 °F
Electrical
Conductivity and insulation.
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Same in both: Electrical Resistivity 1×10¹² Ω·m3.94×10¹⁹ µΩ·in · Dielectric Strength 12 kV/mm305 V/mil · Volume Resistivity 1×10¹⁴ Ω·cm
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
Sintering / Firing Temperature
Same in both: Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
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 | Mullite | Steatite |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$ Premium | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Mullite vs Steatite — frequently asked
Is Mullite stronger than Steatite?
Yes. Mullite has a typical tensile strength of 80 MPa (11.6 ksi) against 60 MPa (8.7 ksi) for Steatite — about 33% more.
Which is cheaper, Mullite or Steatite?
Mullite is the lower-cost material: it sits in the premium tier ($$$) while Steatite is high ($$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose Mullite over Steatite?
Pick Mullite when strength drives the design, or when surface hardness matters. Pick Steatite when weight is the constraint.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Mullite and Steatite 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.