Glassy carbon

Glassy carbon is high-temperature resistant in inert gas or vacuum environments up to 3000°C. Unlike all other ceramic and metallic high-temperature materials, glassy carbon increases in strength with a rise in temperature up to 2400°C. Glassy carbon is thus twice as strong at 2400°C as it is at room temperature.

The material does not become fragile at high temperatures and has a high degree of resistance to thermal shocks. Repeated high-level heating and cooling are not problematic.

Principal characteristics

  • Low heating and smelting times, as the metal melts faster and more homogeneously. Glassy carbon crucibles have a longer life-span than those made of ceramics or ordinary graphite.

  • Glassy carbon crucibles are not porous.

  • Its high degree of purity, the low specific surface area and the isotropic structure of a carbon crucible give rise to a slight oxidation which produces protective gas above the smelted metal helping to prevent the formation of oxide on the molten metal.

  • Uniform casting is possible without wetting the surfaces of the crucible. This property remains intact throughout the life-span of the product.

  • With their high resistance to thermal shocks, crucibles made of glassy carbon will not crack even when placed on cold surfaces when still hot.

  • Glassy carbon crucibles can be used in induction heating.

  • Glassy carbon crucibles are ideally suited for smelting palladium alloys and other alloys containing a percentage of noble metals: they can be used to smelt ceramic alloys containing a percentage of noble metals at approximately 1400°C. Glassy carbon crucibles are also used with rare metals and titanium alloys.

  • Glassy carbon crucibles are not to be used for the smelting of steel or ferrous alloys.

Available standard products

  • Cylindrical crucible
  • Evaporating dish
  • Conical crucible (high angle)
  • Conical crucible (low angle)
  • Lid
  • Crystal growth crucible
  • Crucible with dispensing spout
  • Boat, incinerating dish

Other types are also available

  • Bars, 1 to 10 mm diameter
  • Plates, 0.5 to 6 mm thickness
  • Films, 60 to 180 μm thickness
  • Tubes upon request
  • Powders

Technical data

References

Grade K

Grade G (crucibles)

Density

g/cm³

1.54

1.42

Open porosity

%

0

0

Max. temperature

(vacuum or inert gas)

°C

1000

3000

Electrical resistivity

Ohm.cm

50.10-4

45.10-4

Young’s modulus

GPa

35

35

Flexural strength

MPa

210

260

Compressive strength

MPa

580

480

Vickers hardness

HV

340

230

Thermal expansion (20/200°C)

10-6.K-1

3.5

2.6

Thermal conductivity

W/m.K

4.6

6.3

Permeability coefficient

%

1.10-11

1.10-9

We can machine parts out of glassy carbon from your plans. Contact us for more informations.

Graphite (1.11M)

Technical data sheet graphite.