How does the strength and temperature of artificial graphite change

Update:13-05-2020
Summary:

Artificial graphite electrode is not only widely used i […]

Artificial graphite electrode is not only widely used in industry, but also has important applications in the military field. One type of graphite bomb that can be used to destroy the enemy's power system is the use of graphite electrode conductivity.

 

Graphite bomb is a kind of "soft bomb" that contains graphite electrode powder or graphite wire into the bomb and contains explosives. It is named because it does not kill the enemy soldiers; it is also because of its powerful power supply system. The destructive power is called the power-off bomb, commonly known as the "power killer".

 

Graphite bombs are made of specially treated carbon filaments. The diameter of each carbon filament is quite small, only a few thousandths of a centimeter. Therefore, it can float in high altitude for a long time. Because the carbon filament is processed by fluid energy grinding It has been chemically cleaned, which greatly improves the conductivity of the carbon wire. Graphite bombs explode in the air, which will drop a large amount of graphite wire over the enemy. These carbon fiber clumps like a spider web densely fall to power transmission towers, transformers and other power facilities. When the current flows through the graphite filaments, the current flow accelerates and begins to discharge. If the current is further increased, it will burn the transmission line, causing a short circuit, and even causing a fire due to overheating or excessive current.

 

Graphite bombs are caused by the electrical conductivity of artificial graphite electrode after explosion, which will cause electrical short circuit, which will cause damage. The graphite electrode itself does not have the characteristics of explosion.

 

In the industrial use of graphite electrode, pay attention to whether the temperature of the environment is appropriate, because the temperature will affect the strength of the graphite electrode.

 

The strength of artificial graphite electrode is significantly increased at high temperatures. The tensile strength of graphite is increased by 20% at 1000 degrees than normal temperature, at 2000 degrees is increased by 75% from normal temperature, and some even double the strength at room temperature. The further increase, the intensity will decrease.

 

The relationship between the strength of graphite electrode and temperature is determined by the following two reasons:

 

 

1. Due to the large anisotropy of the thermal expansion coefficient of graphite crystals, after being cooled from high temperature, a large stress will be generated inside the crystal grains. At low temperature, the strength of  graphite electrode is low, which is caused by the superposition of external stress and internal stress, but when heated to a certain temperature, the internal stress gradually decreases, so the strength increases with increasing temperature.

 

 

2. Artificial graphite electrode will not produce local plastic deformation at low temperature, so even if a relatively low load is given, it will cause cracking due to the very concentrated stress. However, when the temperature rises to a certain degree, local deformation occurs near the stress concentration point due to the plastic relationship, and the stress is dispersed, even if a relatively large load is applied, it will not cause cracking.

 

 

The above is the relationship between the strength of artificial graphite electrode and temperature.

 

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