Graphite can be divided into natural graphite and artif […]
Graphite can be divided into natural graphite and artificial graphite. Both have similar structures and similar physical and chemical properties, but their uses are quite different. In many studies, some researchers did not notice the difference between the two and call it graphite in general. The result of conflating the two has caused a lot of misleading and even decision-making errors, resulting in a great waste of resources and economic losses. This article discusses the characteristics and differences, important connections and application progress of natural graphite and artificial graphite from the perspective of the structural composition and performance of natural graphite and artificial graphite.
Graphite classification and characteristics
1. Natural graphite
Natural graphite is formed by the transformation of carbon-rich organic matter under the long-term action of high temperature and high pressure geological environment. It is the crystallization of nature. The process characteristics of natural graphite mainly depend on its crystal form. Minerals with different crystalline forms have different industrial values and uses. There are many types of natural graphite. According to different crystalline forms, the industry divides natural graphite into dense crystalline graphite, flake graphite and cryptocrystalline graphite. There are two main categories of flake graphite and cryptocrystalline graphite in my country.
Natural flake graphite has good high temperature resistance, electrical conductivity, thermal conductivity, lubrication, plasticity, acid and alkali resistance. Four categories are classified according to the fixed carbon content: high purity graphite (FC: 99.9%-99.99%), high carbon graphite (FC: 97-99.8%), medium carbon graphite (FC: 90-96%), low carbon graphite (FC :70-90%).
Natural flake graphite has a melting point above 3000°C, which is one of the most temperature-resistant minerals. The chemical properties are relatively stable at room temperature, with the characteristics of high temperature resistance, acid and alkali corrosion resistance, and high electrical conductivity. It can be used as refractory materials, conductive materials, and wear-resistant lubricating materials.
2. Artificial graphite
Artificial graphite is similar to polycrystals in crystallography. There are many kinds of artificial graphite, and the production process is very different. Broadly speaking, all graphite materials obtained through organic carbonization and graphitization high temperature treatment can be collectively referred to as artificial graphite, such as carbon (graphite) fiber, pyrolytic carbon (graphite), foam graphite, etc. In the narrow sense, artificial graphite usually refers to the use of carbonaceous raw materials (petroleum coke, pitch coke, etc.) with low impurity content as aggregates, coal pitch, etc. as binders, after batching, kneading, molding, and carbonization (industrially called It is a block solid material obtained by baking) and graphitization, such as graphite electrode, hot isostatic pressing graphite, etc.
(Synthetic) graphite powder is also called artificial graphite, usually to distinguish it from natural graphite powder. Artificial graphite powder is produced when graphite electrodes are processed and is a by-product. In addition, petroleum coke powder can also be obtained by calcining and graphitizing. Artificial graphite powder has high purity (98%-99.9% carbon content), excellent lubrication performance, and strong electrical conductivity. Therefore, graphite powder is used as a recarburizer in most cases to increase the carbon content of the product, such as: For steel, reducer, and casting, graphite powder is also widely used in the fire protection industry. Sometimes graphite powder is also used as a battery or brake lining.