1. Applications of graphite electrodes

1.1 Definition of graphite electrode

It is a kind of fire resistant graphitic conducting material which is produced by means of tempering,molding,graphitization and mechanical processing with petroleum coke and pitch coke as granular, and coal pitch as adhesive. It is called artificial graphitic electrode, and graphite electrode for short.

1.2 Operating principle of graphite electrode

Graphite electrode is an important high-temperature conducting material used for smelting in electric furnace. Electric energy is introduced into electric furnace through graphite electrode and melt furnace material for smelting under high temperature which heat source comes from electric arc between ends of electrode and furnace material. Besides, graphite electrode is usually applicable as conducting material in such equipment as electric smelting device, electrolytic device.

2. Grade and detail application of electrode

It is divided into following five grades mainly.

Regular power graphite electrodes (RP)

Impregnated graphite electrodes (IP)

High power graphite electrodes (HP)

Super high power graphite electrodes (SHP)

Ultra high power graphite electrodes(UHP)

3. Characteristics of graphite electrode

As fine high-temperature conducting material, graphite electrode has such advantages as low resistivity, low content of ash, compact structure, good conducting performance, small coefficient of thermal expansion, strong antioxidation and corrosion resistance, especially higher strength under high temperature, so it is an important part among raw material industry at present.

4 . Performance of main indexes

The main indexes to judge the quality of graphite electrode include electric resistivity, bulk density, mechanical strength, thermal conductivity, coefficient of thermal expansion, elastic modulus etc. The precision of machining and reliability of connection are important factors to impact use performance of products also.

4.1 Volume density

It means material mass of test piece in unit volume. It is of great advantage to reduction of air porosity, enhancement of mechanical strength as well as improvement of a ntioxidation that increases volume density.

4.2 Mechanical strength: Generally, the mechanical strength for graphite electrode is measured with three indexes including resist compression, resist folding and tensile.

The ultimate resistibility in the moment when object is acted by foreign force to be bended before it is broken is called strength of folding strength.The mechanical strength for graphite electrode is measured with this folding strength mainly in carbon industry at present.Folding strength is a key index relating to breaking of graphite electrode in the use.

 4.3 Elastic modulus

It is the index to reflect rigidity and brittleness of product. Generally, Young's elastic modulus (vertical elastic modulus) is measured for graphite electrode. Namely, when material is compressed or pulled, it requires stress for unit elastic distortion. The elastic modulus of graphite electrode is relating to its thermal shock resistance directly, which is proportional to its volume density, and increases together with rising of temperature.

4.4 Electric resistivity

It is an important index of physical property for graphite electrode, generally it is measured with method of voltage drop.

The value of resistivity can reflect the extent of graphitization of graphite products. The more resistivity of graphite electrode is low, the more its thermal conductivity is high, and then a ntioxidation becomes better.

4.5 Thermal conductivity

It means that test piece transfers heat quantity per unit area in unit time in the grads of unit temperature.

4.6. Coefficient of thermal expansion

It is a parameter to reflect extent that material expands when it is heated. Namely, it means proportional constant that test piece of solid material at unit length is expanded in certain direction when the temperature rise 1 degree. It is called coefficient of linear expansion in this direction.Coefficient of thermal expansion of carbon product is divided into coefficient of linear expansion and coefficient of radial expansion mainly. And now, coefficient of linear expansion is tested in China among the temperature of 100-600 degree (in some foreign countries, test is carried out in the condition of 30-100 degree abroad).

4.7 Thermal Shock Resistance