SIGRAFINE® isostatic graphites

What is isostatic graphite?

Isostatic graphite is an ultra-fine grain graphite used for applications where the mechanical properties of other fine grain graphites are inadequate.

The term "isostatic graphite" stands for isostatically molded graphite. This means that the raw material mixture is compressed into rectangular or round blocks in a so called Cold-Isostatic-Press (CIP).

Compared to other technologies such as extrusion or vibration molding, this technology can produce the most isotropic form of artificial graphite. In addition, isostatic graphite generally tends to have the smallest grain sizes of all artificial graphites.

The production of isostatic graphite started in the 1960s with SGL Carbon’s plant in Bonn (Germany) being one of the first in the world to manufacture material with a constant quality, suitable for applications in the nuclear and metallurgical industries.

Extremely high thermal and chemical resistance
Excellent thermal shock resistance
High electrical conductivity
High thermal conductivity
Increasing strength with rising temperature
Easy to machine
Can be produced with very high purity < 5 ppm

Nowadays isostatic graphite represents a large part of the fine-grain graphite market and has found applications in over 30 different industries, from nuclear and metallurgical applications to semiconductor, solar, continuous casting, EDM and many others.

SGL Carbon produces several isostatic graphite grades, each with distinct properties that make it ideally suited for specific application environments.

Please contact us for further information on any materials or technology-related advice.

Our Product Finder for SIGRAFINE Fine-Grain Graphite can help you pre-select the appropriate graphite grades for your application.

The production processes for synthetic carbon and synthetic graphite materials are equivalent to those applied in the ceramic industry. The solid raw materials coke and graphite are first milled and then mixed with binder pitch in mixers to form a homogeneous mass. Afterwards the shaping process such as isostatic pressing, extrusion, vibration molding, or die molding takes place.

The shaped bodies, called "green" material, are then carbonized in an oxygen free environment at about 1000°C . In this process, the binder bridges between the solid particles are formed. Graphitization – the second thermal processing step – will then transform the amorphous carbon into 3-D-ordered graphite at roughly 3000°C.

Afterwards, they can undergo further mechanical processing to be turned into complex shapes. Optional further refinements such as purification and coating e.g. with silicon carbide are possible.