SPI-Glas™ Brand Glassy (Vitreous) Carbon Crucibles

Select from three standard shapes/sizes

SPI-Glas™ Brand glassy carbon, some times referred to as "vitreous" carbon, can be fashioned into crucibles and bowls which are universally used in laboratories worldwide for carrying out chemical analyses and also for the preparation of fluorophosphate and other glassy materials. Crucibles fabricated in SPI-Glas™ Brand glassy carbon are also used in the growing of single crystals and other ultra-high purity materials. The SPI-Glas™ Brand glassy carbon also exhibits excellent biological compatibility with live tissues and therefore has high potential for applications in life science research and medicine generally.

One of the wider applications for SPI-Glas™ Brand glassy carbon crucibles is for the melting of precious group metals.

How is SPI-Glas™ Brand glassy carbon different from graphite and "ordinary" carbon?
This glassy carbon should be thought of in perspective with regard to graphite, ordinary carbon, and diamond. Its hardness is close to that of diamond but its appearance (e.g. black) is reminescent of graphite. Quite predictably, the properties of the SPI-Glas™ Brand glassy carbon is considerably different from those of either diamond or graphite.

SPI-Glas™ Brand Glassy Carbon Crucibles exhibit some very unusual properties:

High thermal conductivity (maximum working temperature = 1500°C)
No adhesion of noble metal melts
Longer service life than graphite crucibles
Resistance to thermal shock
Suitability for palladium-containing alloys
Designed for use in induction-heated casting centrifuges

For example, the SPI-Glas™ Brand Glassy Carbon Crucibles, relative to ceramic crucibles, exhibit far higher thermal conductivity and show very little adhesion of precious group metals. Thermal cycling times are reduced, sometimes substantially. This also means that the heater coils can be operated at lower temperatures than would otherwise be mandated if ceramic crucibles were being used.

As a result of the above, the cycle time for a casting is greatly reduced and the useful life of the crucibles is greatly extended.

Useful lifetimes of SPI-Glas™ Brand Glassy Carbon Crucibles:
The useful lifetime of SPI-Glas™ Brand Glassy Carbon Crucibles is much longer than for graphite crucibles because of the much slower oxidation rate of glassy carbon at high temperatures in air. When a reducing atmosphere over the crucible is employed, the resulting virtually zero oxidation rate prevents the formation on the molten metal surface an oxide layer. The melting aids usually associated with the use of ceramic crucibles are normally not needed since the molten metal freely flows out without ever wetting the crucible walls and the casting that is obtained has a uniform and featureless surface. The metal-repelling characteristics of the SPI-Glas™ Brand Glassy Carbon Crucibles remain unchanged throughout the crucible's lifetime.

Resistance to thermal shock:
The SPI-Glas™ Brand Glassy Carbon Crucibles will not fracture when still red hot, are placed on a cold surface.

Application to induction-heating casting centrifuges:
The SPI-Glas™ Brand Glassy Carbon Crucibles are used widely in applications involving induction-heating casting centrifuges. Since glassy carbon crucibles couple in the inductive field (which is not true for ceramic crucibles), they read the desired operating temperature far more quickly, and the metal will melt more quickly, resulting in much shorter cycle times per run.

Applications in dental laboratories:
The SPI-Glas™ Brand Glassy Carbon Crucibles are used extensively in dental laboratories for use with the induction-heated casting centrifuges. They can also be used for the melting of high-Pd containing alloys which will not have defects and will not flake after ceramic veneering.

Precaution:
The SPI-Glas™ Brand Glassy Carbon Crucibles should never be used for the melting of chromium-cobalt-molybdenum alloys. Similarly, they should not be used for melting anything that easily carbides, for example silicon or tungsten.

Available grades:
The SPI-Glas™ Brand Glassy Carbon Crucibles are available in only one grade, SPI-Glas™ 20, which has the same identical properties as premium grade SPI-Glas™ 25, except that its maximum service temperature is 1500°C, not 2500°C

Available crucibles (all in Grade SPI-Glas™ 20):


"Box" Style:	SPI #	Each	In Stock
Volume: 0.3 ml
10 mm OD x 6 mm ID x 12 mm High	4187GC-AB	$41.42	Yes


Volume: 10 ml
26.5 mm OD x 21 mm ID x 32 mm High	4188GC-AB	77.66	Yes
48 mm OD x 27 mm High (45ml)	4189GC-AB *	40.00	Yes
* While Supplies Last


Round bottom:
30 mm OD x 27 mm High, (7 ml)	4190GC-AB	$67.29	Yes


Tapered bottom:
105 mm OD x 150 mm High (800 ml)	4191GC-AB	$414.14	Yes

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