Carbon materials have basic properties such as good electrical and thermal conductivity, electrical properties, lubricity, high temperature properties, chemical corrosion resistance, heat resistance, high temperature thermal peeling resistance, and electrochemical properties. Carbon, especially special graphite, has become an indispensable and important material and industrial material for modern industry. Relying on its inherent characteristics, it is often widely used in the manufacturing process of industrial products in various industries, environments, and production conditions in the form of basic raw materials, molds, appliances, components, and structural materials. The carbon industry is very diversified. It not only has the foundation of traditional industry, but also has opportunities and space for high-tech and high-tech development. The development prospects of the industry are good in the long term. At the same time, the carbon industry also deeply processes and reuses waste residues from the petrochemical and coal chemical industries. It is an industry that uses secondary energy and conforms to the concept of the circular economy.
1. The demand for special graphite in EDM is growing steadily.
The main advantage of EDM is that it is suitable for processing difficult-to-cut materials. The tool electrode does not contact the workpiece, and the force between the two is very small. It is suitable for processing parts with special and complex shapes. In the EDM process, the tool electrode used as the anode can be made of copper or graphite. Compared with copper electrodes, graphite electrodes are lighter than copper, with a density only 20% of copper. They are easy to process, are not prone to stress and thermal deformation during cutting, and have a small thermal expansion coefficient when the melting point is above 3,000°C.
In the demand structure of special graphite, electric discharge machining accounts for about 15% and is one of the downstream users with great demand. The use of high-grade graphite in EDM graphite products is about 25%, and the use of medium- and low-grade graphite is about 75%.
2. Nuclear safety accelerates the application of graphite materials in nuclear power
Nuclear safety has become a key factor in the future development of nuclear power. Some European countries have slowed down or stopped the construction of nuclear power plants. Germany even announced that it will close nuclear power plants in 2020. Our country is also re-examining its nuclear power development plan. But in the long term, nuclear power is still a more promising generating unit with higher power generation efficiency, and my country's long-term plan to vigorously develop nuclear power has not changed. In nuclear power construction, nuclear safety is the top priority. High-temperature gas-cooled reactors are recognized by the international nuclear energy community as a new type of nuclear reactor with higher safety and are the development trend of future nuclear power installations.
Graphite is a neutron moderator and an excellent reflector. It has many excellent properties that establish it as one of the key materials in the nuclear industry. In high-temperature gas-cooled reactors, carbon materials are indispensable deceleration materials, reflective materials, and structural materials. High-temperature gas-cooled reactors require a large amount of high-grade graphite materials. It can be said that without nuclear graphite materials, high-temperature gas-cooled reactors cannot be built. In high-temperature gas-cooled reactors, since helium is used as the coolant, carbon and ceramic materials are used as fuel coating materials, and graphite or carbonaceous materials are used as deceleration materials and furnace core structural materials. High-temperature gases close to 1,000°C can be exported out of the reactor for use as energy. Several high-temperature gas-cooled reactors for development and research have been established internationally. In addition, nuclear graphite can be used to make thermal structural parts, and isotropic carbon graphite materials are used to make nuclear graphite products such as graphite balls, core materials, and electrodes.
3. Other needs: The growth potential of molds, continuous casting, and artificial diamond graphite cannot be ignored
My country uses a large amount of graphite for manufacturing molds and continuous casting, and various types of graphite used for graphite molds and continuous casting account for about 26% of the total demand. The foundry industry in the machinery industry uses graphite materials extensively as processing molds for pressure casting, centrifugal casting, and hot extrusion of superhard alloys. The continuous casting method is mainly used to produce large-sized pure copper, bronze, brass, etc. Among them, the crystallizer, which plays a vital role in product quality, is made of isostatic graphite material. Because isostatically pressed graphite has good properties in terms of heat conduction, thermal stability, self-lubrication, anti-wetting, and chemical inertness, it has become an irreplaceable material for making crystallizers. Isostatic graphite is also used to make diamond tools and cemented carbide sintering molds, thermal field components of optical fiber drawing machines (heaters, insulation cylinders, etc.), thermal field components of vacuum heat treatment furnaces (heaters, load-bearing frames, etc.), as well as precision graphite heat exchangers, mechanical seal components, piston rings, bearings, rocket nozzles, etc.