What is the effect of graphite purity in carbon rods on conductivity and high temperature resistance?

What is the effect of graphite purity in carbon rods on conductivity and high temperature resistance?

The purity of graphite in carbon rods has an important influence on its conductivity and high temperature resistance, as follows:

Effect on conductivity

Graphite has good conductivity because there are free electrons in its crystal structure. In graphite crystals, carbon atoms are arranged in layers, and each layer of carbon atoms forms a hexagonal planar structure through covalent bonds, while the binding force between layers is weak, and there are electrons that can move freely. These free electrons can move in a directional manner under the action of an external electric field, thereby forming an electric current, which makes graphite have good conductivity.

The higher the purity of graphite in carbon rods, the less impurities there are, and the less obstacles there are to the movement of free electrons. In this way, the current passes through the carbon rod more smoothly, the resistance is lower, and the conductivity is better. On the contrary, if the graphite purity is low and there are more impurities, the impurities will interfere with the movement of free electrons, increase the probability of electron scattering, increase the resistance of the carbon rod, and reduce the conductivity.

Effect on high temperature resistance

Graphite has a high melting point and thermal stability. At high temperatures, the covalent bonds between carbon atoms in graphite can remain relatively stable, allowing graphite to withstand high temperatures without melting or decomposition. At the same time, the layered structure of graphite also helps it maintain a certain degree of flexibility and strength at high temperatures, and is not easily broken by thermal stress.

When the purity of graphite in carbon rods is high, its high temperature resistance will also increase accordingly. This is because the structure of high-purity graphite is more regular, and the bond between carbon atoms is tighter and more stable. Under high temperature conditions, high-purity graphite can better maintain the integrity of its crystal structure, reduce defects and weak links that may be caused by the presence of impurities, and thus withstand higher temperatures without performance degradation or damage. If the purity of graphite is not high, the presence of impurities may reduce the melting point of graphite, or react chemically with graphite at high temperatures, destroying the crystal structure of graphite, resulting in a decrease in the high temperature resistance of carbon rods. For example, some metal impurities may oxidize at high temperatures or form low-melting-point compounds with graphite, causing carbon rods to soften and deform at lower temperatures.