Special Properties and Applications of High-purity Graphite

If the 20th century was the age of silicon, carbon will be one of the fastest-growing and most widely used materials of the 21st century. Advanced carbons such as anode materials for lithium batteries, graphene materials, isotropic nuclear graphite, synthetic diamond, and flexible graphite are playing an increasingly important role in people's life, production and military.

Ⅰ. Application of high-purity graphite

High-purity graphite refers to graphite powder containing more than 99.9% carbon, and high-purity graphite with high carbon content. This high-purity graphite has good electrical conductivity, lubricity, high temperature resistance, wear resistance, etc.

The use of high-purity graphite in industrial production has excellent performance. High-purity graphite is used in electrical conductivity, lubrication, metallurgy and other industrial production fields. In the production of high-purity graphite, starting from the raw material, the content of impurities should be strictly controlled, raw materials with low ash content should be selected, and the increase of pollutants should be prevented as much as possible during the production process. However, the reduction of contaminants to the desired level is primarily in the graphitic chemical sequence. Graphitization occurs at high temperatures, and oxides of many impurity elements decompose and evaporate at high temperatures. The higher the graphitization temperature, the more impurities are discharged, and the higher the purity of the high-purity graphite product produced. High-purity graphite is a kind of high purity and less impurities. It depends on the complete production process and production equipment.

Ⅱ. The special properties of high-purity graphite

1. High temperature resistance: the melting point of graphite is 3850±50℃, and the boiling point is 4250℃. Even after ultra-high temperature arc combustion, the weight loss is extremely small, and the thermal expansion coefficient is negligible. As the temperature increases, the strength of high-purity graphite increases. At 2000 °C, the power of graphite doubles.

2. Electrical conductivity and thermal conductivity: The electrical conductivity of high purity graphite block is 100 times higher than that of ordinary non-metallic ores. Thermal conductivity exceeds that of steel, iron, lead and other metallic materials. Thermal conductivity decreases with temperature, and even at very high temperatures, graphite becomes adiabatic. High-purity graphite conducts electricity because each carbon atom in graphite forms only three covalent bonds with other carbons, and each carbon atom retains a free electron to carry an electric charge.

3. Lubricity: The lubricating performance of high-purity graphite powder depends on the size of the graphite flakes. The larger the flakes, the smaller the friction coefficient and the better the lubricating performance.

4. Chemical stability: High-purity graphite has excellent chemical durability, acid resistance, alkali resistance and organic solvent corrosion resistance at room temperature.

5. Plasticity: High-purity graphite has good toughness and can be ground into fragile materials.

6. Thermal shock resistance: High-purity graphite can withstand severe changes in temperature without damage or sudden change in temperature when used at room temperature. The volume of graphite changes little and does not produce cracks.