Glassy Carbon
Glassy Carbon is a non-graphitizing, isotropic carbon made by slow controlled pyrolysis of a thermoset resin, giving a gas-impervious structure with no open porosity (GC-1000 and GC-2300 grades, plus reticulated RVC foam).
Reference datasheet — Glassy Carbon 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 GC-2300 condition
Glassy Carbon tempers and conditions
Glassy Carbon is supplied in 3 conditions, soft to hard. GC-2300 is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Low heat-treatment temperature glassy carbon | Pick for service at or below 1000 °C: the ~1000 °C heat treatment gives higher density and compressive strength at lower cost, but less purity and high-temperature stability than the 2300 °C type. | 110 | 230 HV | 5 W/m·K | ||
GC-2300Default High heat-treatment temperature glassy carbon | Choose this default high-purity, ~2300 °C heat-treated form for electrochemical electrodes, crucibles and semiconductor parts; usable to 3000 °C in an inert atmosphere. | 130 | 340 HV | 6 W/m·K | ||
Reticulated vitreous carbon foam | Use when a conductive open-cell skeleton with high specific surface area is needed — flow-through reactors, current collectors, filtration, high-temperature insulation; strength is very low, light loads only. | 0.1 W/m·K |
What is Glassy Carbon?
Glassy Carbon is a non-graphitizing, isotropic carbon made by slow controlled pyrolysis of a thermoset resin, giving a gas-impervious structure with no open porosity (GC-1000 and GC-2300 grades, plus reticulated RVC foam). It is chosen for near-total chemical inertness (corrosion score 95) and for a 130 MPa tensile strength and 35 GPa modulus well above molded graphite, in crucibles, plates, rods and electrodes with mirror-polishable surfaces. Thermal conductivity is only 6.3 W/m·K, air service is limited to about 600 °C, section thickness is restricted by 20–30 % pyrolysis shrinkage, and parts must be ground rather than machined (machinability 12). Glassy Carbon has a density of 1.42 g/cm³ (0.0513 lb/in³), lighter than 97% of ceramic grades. Glassy Carbon has a tensile strength of 130 MPa (18.9 ksi), stronger than 53% of ceramic grades. Elongation at break is 0.4% and the elastic modulus is 35 GPa (5.08 Msi).
What is Glassy Carbon used for?
- crucibles for metal melting
- electrochemistry electrodes
- high-temperature labware
- biomedical implants coatings
Advantages
- Lightweight — 1.42 g/cm³ (0.0513 lb/in³), better than 97% of ceramic grades
- Good corrosion resistance — 95/100, better than 97% of ceramic grades
- Polishes to a fine finish — 95/100, better than 97% of ceramic grades
- Ductile — tolerates forming and impact — 0.4%, better than 96% of ceramic grades
Limitations
- Low fracture toughness — 0.8 MPa·√m (0.728 ksi·√in), worse than 99% of ceramic grades
- Low stiffness — 35 GPa (5.08 Msi), worse than 86% of ceramic grades
Glassy Carbon properties
Typical room-temperature values for Glassy Carbon-GC-2300; bars are the position among ceramic grades.
Physical2
Glassy Carbon has a density of 1.42 g/cm³ (0.0513 lb/in³), lighter than 97% of ceramic grades.
Mechanical13
Glassy Carbon has a tensile strength of 130 MPa (18.9 ksi), stronger than 53% of ceramic grades. Elongation at break is 0.4% and the elastic modulus is 35 GPa (5.08 Msi).
Thermal5
Glassy Carbon is rated for continuous service to 600°C (1,112 °F). It conducts heat at 6.3 W/m·K (3.64 BTU/hr·ft·°F), worse than 61% of ceramic grades. Thermal expansion is 2.6 µm/m·K (1.44 µin/in·°F).
Electrical2
Glassy Carbon has an electrical resistivity of 4.5×10⁻⁵ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (95/100), better than 97% of ceramic grades.
Sustainability4
Producing a kilogram of Glassy Carbon takes about 300 MJ of energy and emits 22 kg of CO₂ — more than 74% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
Glassy Carbon's machinability is not recommended (12/100, better than 78% 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. Glassy Carbon is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Glassy Carbon
Is Glassy Carbon easy to machine?
Only diamond wheel grinding, wire sawing or laser cutting are practical; feed lightly and chamfer all edges. Do not turn, mill or tap — the material chips and cracks immediately.
Can Glassy Carbon be welded?
Not weldable; connections to metal or quartz rely on mechanical clamping, carbon cement or brazing to a metallized coating.
Can Glassy Carbon be formed, bent or molded?
Net-shape process: the resin is cured in a mold, then pyrolyzed extremely slowly, with roughly 20–30 % linear shrinkage compensated in the mold. Thickness is generally held to a few millimetres to avoid cracking.
Glassy Carbon 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 |
|---|---|---|
| Hhigher residual H in 1000 °C type; near zero in 2300 °C type | 0 – 0.1 | 0.02 |
| ashash typically <50 ppm (<20 ppm high-temperature type) | 0 – 0.01 | 0 |
| Cnon-graphitizing carbon from phenolic/furfuryl/polyfurfuryl resins | ≥ 99.9 (balance) |
What surface finishes work on Glassy Carbon?
Can be polished to a mirror finish (Ra < 10 nm) for electrochemical electrodes; surfaces are activated by plasma or thermal oxidation. Plating is not possible — an acid rinse before use is sufficient.
How much does Glassy Carbon cost?
Glassy Carbon is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Glassy Carbon — frequently asked
What is Glassy Carbon used for?
Glassy Carbon is typically used for crucibles for metal melting, electrochemistry electrodes, high-temperature labware and biomedical implants coatings. In short: most inert carbon form; grind-only, not machinable; thin sections only.
What is the tensile strength of Glassy Carbon?
Glassy Carbon has a typical tensile strength of 130 MPa (18.9 ksi) — stronger than 53% of ceramic grades. Strength varies by condition: see the 3 listed tempers.
Is Glassy Carbon easy to machine?
Not especially — machinability is rated not recommended (12/100, better than 78% of ceramic grades). Only diamond wheel grinding, wire sawing or laser cutting are practical; feed lightly and chamfer all edges. Do not turn, mill or tap — the material chips and cracks immediately.
Can Glassy Carbon be welded?
Not weldable; connections to metal or quartz rely on mechanical clamping, carbon cement or brazing to a metallized coating.
What surface finishes work on Glassy Carbon?
Can be polished to a mirror finish (Ra < 10 nm) for electrochemical electrodes; surfaces are activated by plasma or thermal oxidation. Plating is not possible — an acid rinse before use is sufficient.
Can Glassy Carbon be formed, bent or molded?
Net-shape process: the resin is cured in a mold, then pyrolyzed extremely slowly, with roughly 20–30 % linear shrinkage compensated in the mold. Thickness is generally held to a few millimetres to avoid cracking.
What is the maximum service temperature of Glassy Carbon?
Glassy Carbon is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Glassy Carbon cost?
Glassy Carbon is a high-cost ceramic ($$$$), 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
- SIGRADUR G / SIGRADUR K Glassy Carbon Material Data — HTW Hochtemperatur-Werkstoffe GmbH (2022)
- Engineered Materials Handbook Vol. 4: Ceramics and Glasses — Carbon and Graphite — ASM International (1991)
- Glassy Carbon Plates, Crucibles and Electrodes — Goodfellow / Alfa Aesar (2023)
- Carbon Materials for Advanced Technologies — vitreous carbon chapter — Elsevier (1999)
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.