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.
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.
- 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
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.