C/SiC vs Mullite/Mullite
Composite · grade comparison
C/SiC and Mullite/Mullite are both composite grades. C/SiC is the stronger of the two: tensile strength 150 MPa (21.8 ksi) against 130 MPa (18.9 ksi) for Mullite/Mullite, about 15% more. In exchange, Mullite/Mullite is the more ductile: elongation 0.35% versus 0.3% for C/SiC. C/SiC is lighter (2.1 g/cm³ vs 2.7 g/cm³ for Mullite/Mullite) and Mullite/Mullite is stiffer (70 GPa vs 65 GPa).
C/SiCChoose it when strength drives the design, or when weight is the constraint.
Mullite/MulliteChoose it when the part is bent, formed or impact-loaded.
C/SiC vs Mullite/Mullite: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all composite 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 composite 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
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Compressive Modulus
Same in both: Shear Modulus 25 GPa3.6 Msi
Physical
Density and transition temperatures.
Density
Water Absorption (24 h)
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)
Max Service Temperature (short-term)
Same in both: Min Service Temperature -200°C-328 °F
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: UV / Weathering Resistance 100 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Same in both: Typical Recycled Content 0%
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 composite grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | C/SiC | Mullite/Mullite |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
C/SiC vs Mullite/Mullite — frequently asked
Is C/SiC stronger than Mullite/Mullite?
Yes. C/SiC has a typical tensile strength of 150 MPa (21.8 ksi) against 130 MPa (18.9 ksi) for Mullite/Mullite — about 15% more.
Which is cheaper, C/SiC or Mullite/Mullite?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, C/SiC or Mullite/Mullite?
Mullite/Mullite. Its machinability rates poor (15/100) against not recommended (10/100) for C/SiC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in C/SiC and Mullite/Mullite 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.