Sintered vitreous carbon crucible

Vitreous carbon is resistant to very high temperatures up to 3000°C in inert gas. Unlike many high temperature products, vitreous carbon increases in strength, peaking at 2400°C. It is twice as resistant at 2400°C than at room temperature. There is no weakening of the product at high temperatures and resistance to thermal shock is very high. Temperature increases followed by repeated cooling pose no problem.

Main proprieties

  • Vitreous carbon crucibles have none of the disadvantages of ceramic crucibles such as low heat conduction, adhesion to noble metals and the use of molten salt.

  • Heating and melting times are reduced so metals melt faster and more evenly. Vitreous carbon crucibles have a longer life than conventional ceramic and graphite crucibles.

  • Vitreous carbon crucibles have no porosity.

  • The high purity, low surface area and isotropic structure of vitreous carbon crucibles cause low oxidation, which generates a protective gas above the molten metal. This low oxidation prevents the formation of an oxide layer on the molten metal.

  • Casting has a uniform and clean appearance and can be done without wetting the crucible's surfaces. This property remains unchanged throughout the life of the product.

  • Thanks to their high resistance to thermal shock, vitreous carbon crucibles do not crack, even when placed on a cold surface.

  • Vitreous carbon crucibles can be used for induction heating.

  • Vitreous carbon crucibles are ideally suited to the fusion of palladium alloys and alloys containing a percentage of noble metals: they can be used, for example, to melt a ceramic alloy containing palladium with a percentage of noble metals around 1400°C.

  • Vitreous carbon crucibles can be used for rare metals and titanium alloys.

  • Vitreous carbon crucibles should not be used for melting steel or ferrous alloys.

Available products

  • Cylindrical crucibles
  • Evaporation capsules
  • Conical crucibles (wide and low angle)
  • Covers
  • Crystal growing crucibles
  • Crucibles with spout
  • Dishes

Vitreous carbon crucible (248.95k)

Data Sheet: Vitreous carbon crucible

Crucibles (597.06k)

Technical data sheet crucibles.

FAQs that can help you in this category

Alumina, zirconia or magnesia crucible: which material should I choose based on the thermal analysis?

To help you choose the crucible best suited for your needs Final Advanced Materials considers two criteria: the maximum attainable heating temperature and the material which is to be melted.

Alumina (Al2O3) is the best choice in terms of value for money. It is chemically very inert, and can be used up to 1,700°C.

Zirconia (ZrO2) is more resistant to thermal shock but chemically less stable. Depending on the type of zirconia, it can be used up to 1,800°C.

Magnesia (MgO) is even more inert, and is resistant up to 2,000°C, but it also has the lowest thermal shock resistance.

Up to what maximum temperature can a graphite and vitreous carbon crucible be used?

Graphite, and vitreous carbon, can be used up to 3,000°C in an inert atmosphere or vacuum. However, when used in air these materials oxidise, and can be used only up to approximately 450-500°C.

Final Advanced Materials recommends that you always work in an argon or nitrogen atmosphere, or a vacuum, to optimise use of these materials. In an oxidising atmosphere their use is very limited.

What type of crucible can be used to melt non-ferrous metals and special alloys?

To melt non-ferrous metals and special alloys, Final Advanced Materials recommends the use of graphite or ceramic crucibles.

Graphite and vitreous carbon are recommended for foundry applications due to their excellent thermal conductivity (between 90 and 180 W.m-1.K-1) and their low expansion (between 2 and 5 10-6.K-1). However, these types of crucibles can react with certain oxides and must be used in an inert atmosphere or vacuum.

Alumina (Al2O3) is chemically stable and suitable for less reactive alloys.

Zirconia (ZrO2) has excellent chemical inertia and is suitable for special alloys and reactive materials.

Silicon carbide (SiC) has great thermal conductivity (125 W.m-1.K-1) and low expansion (4.5 10-6.K-1). It is suitable for aluminium, copper and intensive production.

Magnesia (MgO) is resistant to basic environments and nickel-rich alloys.

What is the oxidisation and corrosion resistance of silicon carbide crucibles?

Silicon carbide (SiC) crucibles have limited oxidisation resistance in an oxygen-rich atmosphere. Silicon carbide starts forming a protective layer of silica (SiO2) at 800-1,000°C. At 1,200°C or above, in air, oxidation becomes more substantial, which can embrittle the crucible over the long term. In these cases, Final Advanced Materials recommends working in an inert atmosphere to prevent these problems from appearing, and to make the material remain stable up to 1,600-1,800°C.

Regarding chemical corrosion, silicon carbide (SiC) has excellent chemical resistance to non-ferrous metals. However, it is sensitive to strong acids and powerful oxidisers at high temperature.

How to prevent thermal shock when using ceramic crucibles?

To prevent thermal shock when using ceramic crucibles Final Advanced Materials recommends the following practices:

• control the temperature variations gradually, and limit mechanical stresses

• never heat crucibles, in particular MgO crucibles, at full power from the start (200°C/h)

• prevent thermal gradients, contact with cold surfaces and localised hot spots

• use an inert atmosphere for silicon carbide, graphite or vitreous carbon