PTFE-C25
A carbon-powder-filled PTFE compound offering improved wear resistance, thermal conductivity and reduced permeability compared with virgin PTFE, with good chemical resistance except to strong oxidizers.
Reference datasheet — PTFE-C25 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 C25 condition
PTFE-C25 grades and fills
PTFE-C25 is supplied in 5 conditions, soft to hard. C25 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 |
|---|---|---|---|---|---|
Conductive carbon black filled | Choose when only static dissipation is required and near-virgin mechanical properties must be kept. | 10 | 20 | 220 | 58 Shore D |
25% carbon + 5% graphite | Pick for dry-running oil-free compressor piston/rider rings: lowest friction and best PV of the carbon family. | 11 | 14 | 75 | 66 Shore D |
15% carbon powder filled | Lower filler loading when more ductility/sealability is needed and wear duty is moderate. | 12 | 17 | 130 | 62 Shore D |
C25Default 25% carbon powder filled | Default general-purpose carbon-filled PTFE for dry-running piston/guide rings, valve seats and hydraulic seals. | 12 | 15 | 90 | 65 Shore D |
20% carbon powder filled | Intermediate loading balancing wear resistance and elongation for dynamic seals. | 12 | 16 | 110 | 64 Shore D |
Supply forms, finishes and certifications
Ways PTFE-C25 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
MOLD | Compression-molded sheet / billet | Surface finish |
RAM | Ram-extruded rod / tube | Surface finish |
What is PTFE-C25?
A carbon-powder-filled PTFE compound offering improved wear resistance, thermal conductivity and reduced permeability compared with virgin PTFE, with good chemical resistance except to strong oxidizers. PTFE-C25 has a density of 2.08 g/cm³ (0.0751 lb/in³), heavier than 98% of polymer grades. Its glass-transition temperature is 120°C (248 °F). PTFE-C25 has a yield strength of 12 MPa (1.74 ksi) and a tensile strength of 15 MPa (2.18 ksi) — weaker than 88% of polymer grades. Elongation at break is 90% and the elastic modulus is 1 GPa (0.145 Msi).
What is PTFE-C25 used for?
- Compressor piston rings and rider bands
- Pump seals in oxidizer-free chemical service
- Bearings and bushings
- Valve packing
Advantages
- Good UV / weathering resistance — 98/100, better than 99% of polymer grades
- Conducts heat well — 0.5 W/m·K (0.289 BTU/hr·ft·°F), better than 98% of polymer grades
- High service temperature — 260°C (500 °F), better than 97% of polymer grades
- Low moisture uptake — 0.02%, better than 92% of polymer grades
- Good corrosion resistance — 90/100, better than 82% of polymer grades
Limitations
- Heavy — 2.08 g/cm³ (0.0751 lb/in³), worse than 98% of polymer grades
- High mold shrinkage — 2.5%, worse than 93% of polymer grades
- Hard to polish — 25/100, worse than 90% of polymer grades
- Difficult to weld — 5/100, worse than 89% of polymer grades
- Low strength — 12 MPa (1.74 ksi), worse than 88% of polymer grades
PTFE-C25 properties
Typical room-temperature values for PTFE-C25-C25; bars are the position among polymer grades.
Physical5
PTFE-C25 has a density of 2.08 g/cm³ (0.0751 lb/in³), heavier than 98% of polymer grades. Its glass-transition temperature is 120°C (248 °F).
Mechanical15
PTFE-C25 has a yield strength of 12 MPa (1.74 ksi) and a tensile strength of 15 MPa (2.18 ksi) — weaker than 88% of polymer grades. Elongation at break is 90% and the elastic modulus is 1 GPa (0.145 Msi).
Thermal10
PTFE-C25 is rated for continuous service to 260°C (500 °F). It conducts heat at 0.5 W/m·K (0.289 BTU/hr·ft·°F), better than 98% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical3
PTFE-C25 has an electrical resistivity of 10 Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 82% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of PTFE-C25 takes about 165 MJ of energy and emits 8.5 kg of CO₂ — more than 86% of polymer grades. Typical recycled content is 0%.
Manufacturability6
PTFE-C25's machinability is very good (70/100, better than 74% of polymer grades); weldability not recommended (5/100); formability poor (20/100).
Common Calculations5
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 polymer family
Yield strength against density for every polymer grade FabDigit runs. PTFE-C25 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with PTFE-C25
Is PTFE-C25 easy to machine?
Turns and mills easily with sharp positive-rake carbide or PCD tools and light clamping; the coke filler is abrasive so tools dull faster than on virgin PTFE, and fine conductive dust needs extraction.
Can PTFE-C25 be welded?
Cannot be fusion or solvent welded; join by mechanical clamping, bonding after sodium-etch/plasma surface activation, or by re-sintering in a mould.
Can PTFE-C25 be formed, bent or molded?
Not melt-processable — preform is cold compression-moulded then free-sintered at ~370–380 °C with slow cool; ram extrusion is used for rod and tube, allow ~2–3% sinter shrinkage.
PTFE-C25 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 powder (petroleum coke / carbon bwt%; some grades substitute 5% of it with graphite | 23 – 27 | 25 |
| PTFE (polytetrafluoroethylene)suspension/fine-cut PTFE moulding powder | ≥ 73 (balance) |
What surface finishes work on PTFE-C25?
Machined surfaces stay matte black and cannot be painted or plated without etching; deburr with sharp blades, and stress-relieve (annealing near 250 °C) before final finishing on precision rings.
Equivalent designations
Standards and trade names that resolve to PTFE-C25 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- PTFE + 25% Carbon
How much does PTFE-C25 cost?
PTFE-C25 is a high-cost polymer ($$$$), 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.
PTFE-C25 — frequently asked
What is PTFE-C25 used for?
PTFE-C25 is typically used for compressor piston rings and rider bands, pump seals in oxidizer-free chemical service, bearings and bushings and valve packing. In short: highest-conductivity PTFE compound; dry-running compressor ring grade; avoid strong oxidizers.
What is the yield strength of PTFE-C25?
PTFE-C25 has a typical yield strength of 12 MPa (1.74 ksi) and a tensile strength of 15 MPa (2.18 ksi) — weaker than 88% of polymer grades. Strength varies by condition: see the 5 listed tempers.
Is PTFE-C25 easy to machine?
Yes — machinability is rated very good (70/100, better than 74% of polymer grades). Turns and mills easily with sharp positive-rake carbide or PCD tools and light clamping; the coke filler is abrasive so tools dull faster than on virgin PTFE, and fine conductive dust needs extraction.
Can PTFE-C25 be welded?
Not readily — weldability is rated not recommended (5/100). Cannot be fusion or solvent welded; join by mechanical clamping, bonding after sodium-etch/plasma surface activation, or by re-sintering in a mould.
What surface finishes work on PTFE-C25?
Machined surfaces stay matte black and cannot be painted or plated without etching; deburr with sharp blades, and stress-relieve (annealing near 250 °C) before final finishing on precision rings.
Can PTFE-C25 be formed, bent or molded?
Not melt-processable — preform is cold compression-moulded then free-sintered at ~370–380 °C with slow cool; ram extrusion is used for rod and tube, allow ~2–3% sinter shrinkage.
What is the maximum service temperature of PTFE-C25?
PTFE-C25 is rated for continuous use to about 260°C (500 °F), and briefly to 300°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between PTFE-C25 C25 and PTFE-C25 CB-ESD?
C25 is the default condition — default general-purpose carbon-filled PTFE for dry-running piston/guide rings, valve seats and hydraulic seals. CB-ESD: choose when only static dissipation is required and near-virgin mechanical properties must be kept. Yield strength is 12 MPa in C25 versus 10 MPa in CB-ESD.
How much does PTFE-C25 cost?
PTFE-C25 is a high-cost polymer ($$$$), 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
- ASTM D4745 — Filled Compounds of PTFE Molding and Extrusion Materials — ASTM International (2021)
- ASTM D4894 — PTFE Granular Molding and Ram Extrusion Materials — ASTM International (2019)
- Filled PTFE compound datasheets (carbon, carbon/graphite grades) — Ensinger / Zeus / Chemours (Teflon design handbook) (2023)
- Engineered Materials Handbook Vol.2 — Engineering Plastics — ASM International (1988)
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.