Definition - What does Isostatic Graphite mean?
Isostatic graphite is a type of graphite with an ultra-fine grain that is used for specific purposes where the mechanical properties found in other fine-grained graphites are insufficient. Among it's other desirable properties, isostatic graphite is corrosion resistant.
Isostatic graphite is also known as isostatically molded graphite, which is a reference to the means by which the raw material mixture is compressed into rectangular or round shaped blocks in a system called cold isostatic pressing (CIP). Cold isostatic pressing is a material processing method where a change in pressure of an enclosed incompressible fluid is conveyed unchanged to every part of the fluid including to the surface of its container.
Compared to other technologies like extrusion and vibration molding, CIP technology produces artificial graphite of the most isotropic form. Isostatic graphite also generally tends to have the smallest grain sizes (on the order of 20 microns) that can be found in artificial graphites.
Isostatic graphite production started in the 1960s at the SGL Carbon plant in Bonn, Germany as one of the very first in the world to manufacture materials that had a constant quality and were also suitable for applications in the nuclear and metallurgical industries.
Corrosionpedia explains Isostatic Graphite
Properties of Isostatic Graphite
Isostatic graphite is a different type of graphite material that differs from the other types of artificial graphite and has better physical properties with isotropy in the whole structure. Some properties of isostatic graphite that make it the best graphite with fine grains include:
- High thermal conductivity
- High electrical conductivity
- Structural balance
- High purity
- High density
- High mechanical strength
- Superior thermal shock resistance
- High temperature resistance
- Chemical resistance
- Resistance to both oxidation and corrosion
All of the aforementioned properties make isostatic graphite a premium choice for precision machining. Therefore, graphite materials are widely used in various industries due to its unique combination of thermal, mechanical, chemical and physical properties. It also sees use in metallurgy, energetics, the manufacturing of fire-resistant materials, electrical machines and facilities.
Both natural and artificial graphite materials are often used in these industries. Artificial graphite is highly regarded due to its clearness and is classified based on the method by which it was manufactured and the application conditions for which it is intended.
Composites made from this material are similar to the strength parameters of steel while possessing high electrical and thermal conductivity.
There are some industries that would be hard-pressed to operate without graphite. For example, the isostatic graphite electrodes found in electrical discharge machines makes it possible to achieve a significant increase in the accuracy of metal processing.
Isostatic graphite is used to manufacture products with complex shapes that have a high surface finish. In the steel industry, isostatic graphite is used to making permanent molds, continuous cast dyes, chutes, etc.
In the electrical field isostatic graphite is used for electronic tubes and semiconductor containers, among others. It is also an essential material for nuclear power reactors and solar photovoltaic cells.