C/SiC
also Cesic
A carbon-fiber-reinforced ceramic matrix composite with a SiC matrix (often via polymer infiltration/pyrolysis or LSI), offering high toughness and thermal shock resistance for aerospace hot structures and brake systems.
Reference datasheet — C/SiC is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the LSI condition
C/SiC grades and fills
C/SiC is supplied in 5 conditions, soft to hard. LSI is the default FabDigit quotes; the values on this page are for it.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Short/chopped fibre brake grade | Use the chopped-carbon-fibre, silicon-melt-infiltrated brake grade for carbon-ceramic discs and clutch plates: quasi-isotropic, 35 W/m·K and wear resistant, but only 40 MPa tensile. | 40 | 0.15 | ||
LSIDefault LSI / MI | Choose the liquid-silicon-infiltrated route for the lowest cost and highest density in brake discs, optical structures and mid-temperature hot structures; residual free silicon caps use near 1350 °C. | 150 | 0.3 | ||
3D woven / needled preform | Pick the 3D woven or needled preform for throat inserts, joints and other triaxially loaded parts, where through-thickness fibres markedly raise interlaminar shear and delamination resistance. | 180 | 0.5 | ||
Polymer infiltration & pyrolysis matrix | Use polymer infiltration and pyrolysis for large thin-wall complex parts such as radomes and nozzle extensions; repeated infiltration-pyrolysis cycles leave shrinkage cracks and lower density, 1.9 g/cm³. | 220 | 0.4 | ||
Chemical vapour infiltration matrix | Pick chemical vapour infiltration when matrix purity, mechanical performance (300 MPa) and minimal fibre damage matter for aero-engine and rocket hot sections; accept 10–15 % porosity, long cycles and highest cost. | 300 | 0.6 |
Supply forms, finishes and certifications
Ways C/SiC is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
2D | 2D woven / laminated fibre architecture | Surface finish |
SIC-CTD | SiC-coated | Surface finish |
What is C/SiC?
A carbon-fiber-reinforced ceramic matrix composite with a SiC matrix (often via polymer infiltration/pyrolysis or LSI), offering high toughness and thermal shock resistance for aerospace hot structures and brake systems. C/SiC has a density of 2.1 g/cm³ (0.0759 lb/in³), heavier than 78% of composite grades. C/SiC has a tensile strength of 150 MPa (21.8 ksi), weaker than 57% of composite grades. Elongation at break is 0.3% and the elastic modulus is 65 GPa (9.43 Msi).
What is C/SiC used for?
- rocket nozzle liners
- re-entry thermal protection panels
- high-performance brake discs
- turbine engine hot-section components
- furnace fixtures
Advantages
- High service temperature — 1,350°C (2,462 °F), better than 98% of composite grades
- Good UV / weathering resistance — 100/100, better than 93% of composite grades
- Polishes to a fine finish — 60/100, better than 90% of composite grades
- Conducts heat well — 20 W/m·K (11.6 BTU/hr·ft·°F), better than 78% of composite grades
Limitations
- Limited ductility — 0.3%, worse than 95% of composite grades
- Difficult to machine — 10/100, worse than 91% of composite grades
- High embodied carbon — 45 kg CO₂/kg, worse than 90% of composite grades
- Heavy — 2.1 g/cm³ (0.0759 lb/in³), worse than 78% of composite grades
C/SiC properties
Typical room-temperature values for C/SiC-LSI; bars are the position among composite grades.
Physical2
C/SiC has a density of 2.1 g/cm³ (0.0759 lb/in³), heavier than 78% of composite grades.
Mechanical10
C/SiC has a tensile strength of 150 MPa (21.8 ksi), weaker than 57% of composite grades. Elongation at break is 0.3% and the elastic modulus is 65 GPa (9.43 Msi).
Thermal6
C/SiC is rated for continuous service to 1,350°C (2,462 °F). It conducts heat at 20 W/m·K (11.6 BTU/hr·ft·°F), better than 78% of composite grades. Thermal expansion is 2.5 µm/m·K (1.39 µin/in·°F).
Electrical1
C/SiC has an electrical resistivity of 0.001 Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 54% of composite grades. UV resistance is excellent.
Sustainability3
Producing a kilogram of C/SiC takes about 700 MJ of energy and emits 45 kg of CO₂ — more than 90% of composite grades. Typical recycled content is 0%.
Manufacturability2
C/SiC's machinability is not recommended (10/100, worse than 91% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. C/SiC is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C/SiC
Is C/SiC easy to machine?
Near-net shaping is the rule. Once densified, only diamond grinding, ultrasonic machining or laser/waterjet cutting is practical; conventional carbide tooling must not be used because it severs fibers and initiates delamination.
Can C/SiC be welded?
Not fusion weldable. Join by silicide brazing, glass-ceramic adhesive bonding, or bolted/pinned attachment to metal parts, matching CTE to avoid thermal-stress cracking.
Can C/SiC be formed, bent or molded?
Form the fiber preform first (weaving, lay-up or needling) and trim it in the green state, then densify by CVI, PIP or LSI. The finished part cannot be reshaped.
C/SiC chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| carbon fiber (PAN/pitch)Volume fraction approx. equals weight fraction; 2D/3D preform | 35 – 55 | 45 |
| free SiResidual free Si only in LSI/melt-infiltration routes | 0 – 20 | 8 |
| residual C matrixUnconverted pyrolytic carbon from LSI/PIP | 0 – 15 | 5 |
| porosityvol%; highest for CVI, lowest for LSI | 1 – 15 | 5 |
| PyC/BN interphaseInterphase layer; determines non-brittle fracture | 0.1 – 2 | 0.5 |
| SiC matrixformed by CVI/PIP/LSI | ≥ 35 (balance) |
What surface finishes work on C/SiC?
CVD SiC coatings or Si-based pore sealing are used to improve oxidation resistance. Optical parts can be SiC-clad and polished to nanometre-level figure; phosphate or glass coatings are applied for emissivity control.
Equivalent designations
Standards and trade names that resolve to C/SiC in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Cesic
How much does C/SiC cost?
C/SiC is a high-cost composite ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C/SiC — frequently asked
What is C/SiC used for?
C/SiC is typically used for rocket nozzle liners, re-entry thermal protection panels, high-performance brake discs, turbine engine hot-section components and furnace fixtures. In short: lightest hot-structure CMC; high thermal-shock resistance; brake and nozzle grade.
What is the tensile strength of C/SiC?
C/SiC has a typical tensile strength of 150 MPa (21.8 ksi) — weaker than 57% of composite grades. Strength varies by condition: see the 5 listed tempers.
Is C/SiC easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 91% of composite grades). Near-net shaping is the rule. Once densified, only diamond grinding, ultrasonic machining or laser/waterjet cutting is practical; conventional carbide tooling must not be used because it severs fibers and initiates delamination.
Can C/SiC be welded?
Not fusion weldable. Join by silicide brazing, glass-ceramic adhesive bonding, or bolted/pinned attachment to metal parts, matching CTE to avoid thermal-stress cracking.
What surface finishes work on C/SiC?
CVD SiC coatings or Si-based pore sealing are used to improve oxidation resistance. Optical parts can be SiC-clad and polished to nanometre-level figure; phosphate or glass coatings are applied for emissivity control.
Can C/SiC be formed, bent or molded?
Form the fiber preform first (weaving, lay-up or needling) and trim it in the green state, then densify by CVI, PIP or LSI. The finished part cannot be reshaped.
What is the maximum service temperature of C/SiC?
C/SiC is rated for continuous use to about 1,350°C (2,462 °F), and briefly to 1,650°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does C/SiC cost?
C/SiC is a high-cost composite ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Ceramic Matrix Composites: Fiber Reinforced Ceramics and their Applications (W. Krenkel, ed.) — Wiley-VCH (2008)
- Engineered Materials Handbook Vol. 4: Ceramics and Glasses — ASM International (1991)
- C/C-SiC and Cesic CMC material data — Schunk / ECM (ECM Engineered Ceramic Materials) (2020)
- Cerasep CMC product information — Safran Ceramics (2021)
- SGL Carbon SIGRASIC C/SiC — SGL Carbon (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.