Graphite Felt CF (Carbon felt, carbonised only)
Reinforced grade
Lower-cost, higher-resistivity felt for service below ~1600 °C and for redox-flow-battery / filtration electrodes.
Values for the CF condition
Other Graphite Felt tempers and conditions
Graphite Felt is listed in 4 conditions; see the grade overview at Graphite Felt.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Rayon (viscose)-based, halogen-purified high-purity graphite felt | Use in single-crystal silicon, sapphire and semiconductor furnaces where ash/metal contamination and out-gassing must be minimal. | — | 0.2 | 12 | — | 0.08 W/m·K |
SGFDefault Soft graphite felt, PAN-based, needled | Default flexible insulation blanket/roll for vacuum and inert-gas hot zones; cheapest and easiest to wrap around cylindrical chambers. | — | 0.3 | 10 | — | 0.09 W/m·K |
CFThis page Carbon felt, carbonised only | Lower-cost, higher-resistivity felt for service below ~1600 °C and for redox-flow-battery / filtration electrodes. | — | 0.4 | 8 | — | 0.08 W/m·K |
Rigid graphite felt board | Pick when the insulation must be self-supporting, machinable to shape, or must resist gas erosion in a vacuum furnace hot zone. | — | 0.8 | — | — | 0.2 W/m·K |
What is Graphite Felt CF?
Graphite Felt CF is Graphite Felt in the CF grade — lower-cost, higher-resistivity felt for service below ~1600 °C and for redox-flow-battery / filtration electrodes. Graphite Felt CF has a tensile strength of 0.4 MPa (0.058 ksi), weaker than 98% of ceramic grades. Elongation at break is 8% and the elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi). Graphite Felt CF has a density of 0.09 g/cm³ (0.0033 lb/in³), lighter than 99% of ceramic grades. It melts at 3,650°C (6,602 °F). SGF is the default condition FabDigit quotes; CF is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 8%, better than 100% of ceramic grades
- Lightweight — 0.09 g/cm³ (0.0033 lb/in³), better than 99% of ceramic grades
- Easy to machine — 95/100, better than 99% of ceramic grades
- High service temperature — 1,600°C (2,912 °F), better than 86% of ceramic grades
Limitations
- Low stiffness — 0.01 GPa (7.25×10⁻⁴ Msi), worse than 99% of ceramic grades
- Poor heat conductor — 0.08 W/m·K (0.0462 BTU/hr·ft·°F), worse than 99% of ceramic grades
- High embodied carbon — 25 kg CO₂/kg, worse than 78% of ceramic grades
Graphite Felt CF properties
Typical room-temperature values for Graphite Felt CF; 14 are specific to this condition. Other listed values are Graphite Felt reference data and may not represent this condition. Bars are the position among ceramic grades.
Physical3
Graphite Felt CF has a density of 0.09 g/cm³ (0.0033 lb/in³), lighter than 99% of ceramic grades. It melts at 3,650°C (6,602 °F).
Mechanical6
Graphite Felt CF has a tensile strength of 0.4 MPa (0.058 ksi), weaker than 98% of ceramic grades. Elongation at break is 8% and the elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi).
Thermal4
Graphite Felt CF is rated for continuous service to 1,600°C (2,912 °F). It conducts heat at 0.08 W/m·K (0.0462 BTU/hr·ft·°F), worse than 99% of ceramic grades.
Electrical2
Graphite Felt CF has an electrical resistivity of 0.03 Ω·m.
Chemical & Environmental2
Corrosion resistance is good (65/100), worse than 67% of ceramic grades.
Sustainability3
Producing a kilogram of Graphite Felt CF takes about 300 MJ of energy and emits 25 kg of CO₂ — more than 74% of ceramic grades. Typical recycled content is 5%.
Manufacturability2
Graphite Felt CF's machinability is excellent (95/100, better than 99% of ceramic grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Graphite Felt CF
Is Graphite Felt easy to machine?
Soft felt is cut with a razor blade, die or waterjet; rigid board is sawn/milled dry with carbide tools — always use HEPA dust extraction and avoid coolant absorption.
Can Graphite Felt be welded?
Not weldable; joined mechanically with graphite pins, CFC screws, graphite foil clamps or carbonising cement.
Can Graphite Felt be formed, bent or molded?
Supplied as needled roll or press-moulded rigid board; soft felt drapes and wraps to small radii and can be layered/compressed to tune conductivity.
What surface finishes work on Graphite Felt?
Optionally faced with graphite foil, CFC skin or SiC/pyrocarbon CVD coating to stop erosion and dusting; halogen purification at ~2000 °C removes metallic ash.
Graphite Felt 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 |
|---|---|---|
| ash≤500 ppm standard; ≤50 ppm for halogen-purified high-purity grade | 0.01 – 0.5 | 0.05 |
| Nresidual nitrogen in PAN-based, carbonised (non-graphitised) felt only | ≤ 0.5 | 0.2 |
| Cgraphitised carbon fibre; purified grades ≥99.99 % | ≥ 99 (balance) | — |
Graphite Felt CF — frequently asked
What is Graphite Felt CF used for?
Graphite Felt CF is typically used for furnace hot-zone insulation, crystal-growth furnace lining and electrode felt for redox-flow batteries. In short: lowest-conductivity graphite insulation; 2200 °C in inert atmosphere; no load-bearing capability.
What is the tensile strength of Graphite Felt CF?
Graphite Felt CF has a typical tensile strength of 0.4 MPa (0.058 ksi) — weaker than 98% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is Graphite Felt CF easy to machine?
Yes — machinability is rated excellent (95/100, better than 99% of ceramic grades). Soft felt is cut with a razor blade, die or waterjet; rigid board is sawn/milled dry with carbide tools — always use HEPA dust extraction and avoid coolant absorption.
Can Graphite Felt CF be welded?
Not weldable; joined mechanically with graphite pins, CFC screws, graphite foil clamps or carbonising cement.
What surface finishes work on Graphite Felt CF?
Optionally faced with graphite foil, CFC skin or SiC/pyrocarbon CVD coating to stop erosion and dusting; halogen purification at ~2000 °C removes metallic ash.
Can Graphite Felt CF be formed, bent or molded?
Supplied as needled roll or press-moulded rigid board; soft felt drapes and wraps to small radii and can be layered/compressed to tune conductivity.
What is the maximum service temperature of Graphite Felt CF?
Graphite Felt CF is rated for continuous use to about 1,600°C (2,912 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- SIGRATHERM soft and rigid graphite felt insulation data sheets — SGL Carbon (2022)
- Carbon and graphite felt / rigid board hot-zone insulation — Kureha / Mersen (2021)
- ASM Handbook Vol. 4 — Heat Treating (furnace insulation materials) — ASM International (1991)
- GB/T 32545 / (industry practice) — SAC (2016)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.