Vitreous Carbon Crucibles are made from a ceramic carbon based material. It has the appearance of black glass and it is fragile. It has a closed micro-porosity and is impervious to gas. Vitreous Carbon has good resistance to thermal shock because of a relatively good thermal conductivity. Vitreous Carbon is sometimes referred to as Glassy Carbon.
Vitreous Carbon is related to graphite crystal but with a very large disorder and submicron voids. It has a low density of 1.51 gm/cc as compared with 2.25 gm/cc for theoretical density of graphite crystal. Vitreous Carbon is unusual in that when it is treated at 2500°C and over it very slightly modifies its crystallographic structure.
Almath Crucibles offers Vitreous Carbon in a Grade A quality only. The operating temperature, when heat treated, of Grade A Vitreous carbon is 2500°C. The normal operating temperature for it is 2000°C and it may be used up to 2800°C in a non-oxygen atmosphere but at this maximum temperature some of the properties of Vitreous Carbon may change.