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Density of Graphite Electrode

Release time:2019-11-04 From: Zhengnai Industry in China

True density definition

True density refers to the mass of material per unit volume of material excluding pores. Commonly used measurement methods are solvent replacement, gas replacement, and X-ray diffractometry.

Approximate value by solvent displacement method

The true density measured by solvent displacement is only an approximation because solvent molecules cannot enter all voids, and different solvents, different wetting conditions, and different particle size samples have different results.


More accurate vacuum density measured with nitrogen

Nitrogen is used to fill the voids in the aggregate particles of the carbon material, and the nitrogen gas can enter all the voids except the closed pores. Therefore, the volume of the sample obtained by the nitrogen displacement method is closer to the true volume, so that the true density measured is More precise.

Use of measuring true density

To determine the true density of different types of carbonaceous raw materials, roasted semi-finished products or graphite electrodes, it is possible to understand the degree of carbonization of the raw materials and the degree of heat treatment under different conditions, such as the degree of calcination, the degree of calcination, and the degree of graphitization.


Measuring true density is important for production

Determining the true density is important for guiding production. From the true density, other physical and chemical properties can be inferred. For example, the true density is inversely proportional to the resistivity of the raw material or the finished product, and the true density is proportional to the antioxidant capacity of the material.

Density definition

Density (bulk density) refers to the mass of a substance per unit volume of a raw material pellet or a finished sample.

Parameter of UHP/RP graphite electrode

Item Unit UHP RP
300-600mm 650-800mm 300-800mm
Electric resistivity Electrode μΩm 4.8-5.8 4.6-5.8 7.8-8.8
Nipple 3.8-4.5 3.8-4.5 5.0-6.5
Flexural strength Electrode Mpa 10.0-14.0 10.0-14.0 7.0-12.0
Nipple 20.0-26.0 22.0-26.0 15.0-20.0
Elastic modulus Electrode Gpa 9.0-13.0 10.0-14.0 7.1-9.3
Nipple 15.0-18.0 15.0-18.0 12.0-14.0
Bulk density Electrode ≥g/cm3 1.68-1.74 1.70-1.74 1.53-1.56
Nipple 1.77-1.82 1.78-1.84 1.70-1.74
CTE(100-600℃) Electrode x10-6/℃ 1.1-1.4 1.1-1.4 2.2-2.6
Nipple 0.9-1.2 0.9-1.2 2.0-2.5
Ash   0.3 0.3 0.5

Weighing method

The measurement density is mainly measured by weighing. The raw material or the semi-finished product of the graphite electrode and the finished product are cut into a cube or a cylinder of a certain size, dried in an oven at 105-110 ° C for 5 hours, taken out and cooled to room temperature, and the size is accurately measured and the volume is calculated. Weigh on the balance.

Graphitization process is related to density

The density of petroleum coke is increased after calcination, but it is generally reduced after graphitization, with the exception of some bituminous coke, which is related to the increase of true density and volume change of coke during graphitization.


Density affects mechanics and thermal properties

Density is an important quality indicator for carbon and graphite products. The density affects the mechanical and thermal properties of raw materials or finished products to some extent.

Factors affecting density

The density of the graphite electrode is related to the type of raw material used, and has a great relationship with the particle size composition of the compound and the amount of the binder, and is also related to the process parameters such as kneading quality, molding pressure, calcination or graphitization temperature.