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Quality Index of Graphite Electrode

Graphite electrodes are used primarily in the EAF steelmaking process for melting scrap steel. The electrode made from graphite is resistant to high temperatures. An electric arc furnace can heat the electrode to 3000 degrees Fahrenheit. That’s half the temperature of the earth. It can vary in size from 75 to 750 mm and up to 2800 mm long. These are key indicators for graphite electrode performance and quality: bulk density, electrical resistance r, bending force, elastic modulus e, thermal expansion coefficients a, and ash content %. These graphite-electrode indicators, as well as the differences among different manufacturing processes and standards in various countries, are what distinguish graphite electrodes into three types: ordinary power graphite (RP), ultra high power graphite (HP) and ultrahigh power (UHP). Following the production of graphite, the plant may add graphite-density electrodes (“HD”) and quasisuper-high graphite electros (“SHP”) depending on different functional needs.

National standards are the foundation of each company’s corporate standards. Customers will create their own quality standards. A relative volume density measures the proportion of graphite material samples that are quality managed to their volumes. The unit of measure is g/cm3. A working electrode’s volume density determines its strength and efficiency. It is generally true that the electrode’s resistivity will be lower if it has a greater volume density.

For measuring conductivity of electrodes, resistance is an indicator. The resistance of the conductor to current is measured when current passes through the conductor. The resistance value of a conductor of length 1m with cross-sectional area 1m2 at a temperature of certain reduces the consumption.

It is an indicator of how well the mechanical system in graphite structures material performs. Also known as the Flexural Strength, it is a measure of how strong the graphite structure material’s mechanical system performs. The object will bend to resist risk if the force exerted on it is parallel to its axis. MPa is the unit of capacity. When using the network, high-strength joint and electrodes are less likely break.

Modulus of Elasticity is an important part of mechanical property. The modulus of elastic is an indicator to determine the material’s elastic ability. This refers the strain-stress ratio within the elastic limit. Simply put, the larger the elastic modulus for brittle materials is, the more elastic deformation it will generate.

An important thermal performance parameter is graphite’s temperature expansion coefficient. Chinese products are more stable if their thermal expansion coefficient is lower than it is. Performance can be reflected in the lower consumption of the product and the reduced fractures.

The term ash refers to any other component in solid products than carbon graphite. The raw material used has a direct impact on graphite’s ash contents. Low ash levels are found in petroleum coke needle coalke. The electrode’s ash contents should be no more than 0.5%. A ash content below 1% will have little effect on steelmaking. The performance of the antioxidation system on the electrode will be affected by the presence of impurities.

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