Amorphous Graphite
Amorphous Graphite is a low-crystallinity natural graphite with lower fixed carbon than flake grades, offered as C75, C85, C90 and C95 by carbon content.
Reference datasheet — Amorphous Graphite 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 C85 condition
Amorphous Graphite tempers and conditions
Amorphous Graphite is supplied in 4 conditions, soft to hard. C85 is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Fixed carbon 70–80 %, run-of-mine / low grade | Cheapest grade for foundry coatings, refractory ramming mixes and low-spec carbon raising where ash is tolerated. | 4 | 0.15 | 25 HV | 10 W/m·K | |
C85Default Fixed carbon 80–85 %, standard commercial grade | Default workhorse grade: steel/iron carbon raiser, refractory and friction-material filler at lowest cost per unit carbon. | 5 | 0.2 | 15 HV | 20 W/m·K | |
Fixed carbon 88–92 %, beneficiated grade | Beneficiated grade for pencil leads, lubricant/conductive fillers and carbon brushes where lower ash is required. | 6 | 0.2 | 12 HV | 30 W/m·K | |
Fixed carbon ≥94 %, chemically purified | Acid/alkali-purified high-carbon grade for battery, conductive-coating and high-grade refractory use where ash must be minimal. | 7 | 0.25 | 10 HV | 40 W/m·K |
What is Amorphous Graphite?
Amorphous Graphite is a low-crystallinity natural graphite with lower fixed carbon than flake grades, offered as C75, C85, C90 and C95 by carbon content. It is chosen mainly on cost as a carbon raiser in foundry and steel practice and as a lubricant or friction-material filler, and is supplied as milled powder to a specified mesh. Thermal conductivity is only about 20 W/m·K against roughly 250 W/m·K for flake graphite, green bodies pressed from it are weak, and air service is limited to about 450 °C. Use natural flake graphite where conductivity, purity or foil-forming capability is required. Amorphous Graphite has a density of 2.25 g/cm³ (0.0813 lb/in³), lighter than 86% of ceramic grades. It melts at 3,650°C (6,602 °F). Amorphous Graphite has a tensile strength of 5 MPa (0.725 ksi), weaker than 97% of ceramic grades. Elongation at break is 0.2% and the elastic modulus is 7 GPa (1.02 Msi).
What is Amorphous Graphite used for?
- foundry carbon raiser
- lubricant filler
- brake linings
- pencil lead
Advantages
- Low embodied carbon — 1.2 kg CO₂/kg, better than 99% of ceramic grades
- Easy to machine — 90/100, better than 94% of ceramic grades
- Lightweight — 2.25 g/cm³ (0.0813 lb/in³), better than 86% of ceramic grades
- Ductile — tolerates forming and impact — 0.2%, better than 81% of ceramic grades
Limitations
- Low fracture toughness — 0.8 MPa·√m (0.728 ksi·√in), worse than 99% of ceramic grades
- Low stiffness — 7 GPa (1.02 Msi), worse than 96% of ceramic grades
- Limited service temperature — 450°C (842 °F), worse than 77% of ceramic grades
Amorphous Graphite properties
Typical room-temperature values for Amorphous Graphite-C85; bars are the position among ceramic grades.
Physical2
Amorphous Graphite has a density of 2.25 g/cm³ (0.0813 lb/in³), lighter than 86% of ceramic grades. It melts at 3,650°C (6,602 °F).
Mechanical9
Amorphous Graphite has a tensile strength of 5 MPa (0.725 ksi), weaker than 97% of ceramic grades. Elongation at break is 0.2% and the elastic modulus is 7 GPa (1.02 Msi).
Thermal5
Amorphous Graphite is rated for continuous service to 450°C (842 °F). It conducts heat at 20 W/m·K (11.6 BTU/hr·ft·°F), worse than 55% of ceramic grades. Thermal expansion is 5.5 µm/m·K (3.06 µin/in·°F).
Electrical2
Amorphous Graphite has an electrical resistivity of 0.001 Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (85/100), better than 69% of ceramic grades.
Sustainability4
Producing a kilogram of Amorphous Graphite takes about 15 MJ of energy and emits 1.2 kg of CO₂ — less than 99% of ceramic grades. Typical recycled content is 0%.
Manufacturability1
Amorphous Graphite's machinability is excellent (90/100, better than 94% of ceramic 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 ceramic family
Yield strength against density for every ceramic grade FabDigit runs. Amorphous Graphite is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Amorphous Graphite
Is Amorphous Graphite easy to machine?
Supplied as powder, not machined; pressed/binder-bonded shapes cut easily but produce abrasive, conductive dust requiring extraction.
Can Amorphous Graphite be welded?
Not weldable — joined only by carbonaceous cements or resin/pitch binders in bonded articles.
Can Amorphous Graphite be formed, bent or molded?
Compacted, extruded or isostatically pressed with clay, pitch or resin binder; fine particle size aids packing but low crystallinity gives weak green bodies.
Amorphous Graphite 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 |
|---|---|---|
| Cfixed carbon, default C85 grade | 80 – 85 | 83 |
| volatile matter | 0.5 – 2.5 | 1.5 |
| moisture | 0 – 1 | 0.5 |
| Simportant for carbon-raiser use | 0 – 0.3 | 0.1 |
| ash (SiO2+Al2O3+Fe2O3)mainly silicate gangue | ≥ 12 (balance) |
What surface finishes work on Amorphous Graphite?
Used as-milled to specified mesh (typically 200–800 mesh); surface treatment limited to drying, air classification or acid/alkali purification.
How much does Amorphous Graphite cost?
Amorphous Graphite is a budget-cost ceramic ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Amorphous Graphite — frequently asked
What is Amorphous Graphite used for?
Amorphous Graphite is typically used for foundry carbon raiser, lubricant filler, brake linings and pencil lead. In short: lowest-cost natural graphite; low crystallinity, low conductivity; bulk carbon-raiser powder.
What is the tensile strength of Amorphous Graphite?
Amorphous Graphite has a typical tensile strength of 5 MPa (0.725 ksi) — weaker than 97% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is Amorphous Graphite easy to machine?
Yes — machinability is rated excellent (90/100, better than 94% of ceramic grades). Supplied as powder, not machined; pressed/binder-bonded shapes cut easily but produce abrasive, conductive dust requiring extraction.
Can Amorphous Graphite be welded?
Not weldable — joined only by carbonaceous cements or resin/pitch binders in bonded articles.
What surface finishes work on Amorphous Graphite?
Used as-milled to specified mesh (typically 200–800 mesh); surface treatment limited to drying, air classification or acid/alkali purification.
Can Amorphous Graphite be formed, bent or molded?
Compacted, extruded or isostatically pressed with clay, pitch or resin binder; fine particle size aids packing but low crystallinity gives weak green bodies.
What is the maximum service temperature of Amorphous Graphite?
Amorphous Graphite is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Amorphous Graphite cost?
Amorphous Graphite is a budget-cost ceramic ($), cheaper than about 90% 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
- GB/T 3519 (Microcrystalline graphite) — SAC (2008)
- Industrial Minerals & Rocks — Graphite — SME (2006)
- ASM Handbook, Engineered Materials — Carbon and Graphite — ASM International (1991)
- Mineral Commodity Summaries — Graphite (Natural) — USGS (2024)
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.