Why can graphite replace copper as electrodes?

Graphite overview

Graphite is an allotrope of carbon. It is a gray-black opaque solid. It has stable chemical properties, corrosion resistance, and is not easy to react with acids and alkalis. It burns in oxygen to generate carbon dioxide. It can be strengthened by concentrated nitric acid, potassium permanganate, etc. The oxidant oxidizes and can be used as an anti-wear agent and lubricant. High-purity graphite is used as a neutron moderator in atomic reactors. It can also be used to make crucibles, electrodes, brushes, dry batteries, graphite fibers, heat exchangers, coolers, electric arc furnaces, arc lamps, pencil leads, etc.

Graphite applications

1. Used as a refractory material: Graphite and its products have the characteristics of high temperature resistance and high strength, and are mainly used for the manufacture of graphite crucibles in the metallurgical industry. In steelmaking, graphite is often used as a protective agent for steel ingots and steel ingots, as the lining of metallurgical furnaces.

2. As a conductive material: used in the electrical industry to manufacture electrodes, brushes, carbon rods, carbon tubes, positive electrodes of mercury positive current devices, graphite washers, telephone parts, coatings for television picture tubes, etc.

3. As a wear-resistant lubricating material: Graphite is often used as a lubricant in the machinery industry. Lubricating oil is often not used under high-speed, high-temperature, and high-pressure conditions, while graphite wear-resistant materials can work at high speed and slide at a temperature of (1) 200~2000 ℃ without lubricating oil. Many equipment that transports corrosive media widely use graphite materials to make piston cups, seals and bearings. They do not need to add lubricating oil during operation. Graphite emulsion is also a good lubricant for many metal processing (wire drawing, pipe drawing).

4. Graphite has good chemical stability. Specially processed graphite has the characteristics of corrosion resistance, good thermal conductivity, and low permeability. It is widely used in the production of heat exchangers, reaction tanks, condensers, combustion towers, absorption towers, coolers, heaters and filters.

Pump equipment. It is widely used in petrochemical industry, hydrometallurgy, acid-base production, synthetic fiber, papermaking and other industrial sectors, which can save a lot of metal materials.

5. Used for casting, sand hunting, pressing molds and high temperature metallurgical materials: Because graphite has a small thermal expansion coefficient, it can withstand rapid changes in cold and heat, and can be used as a mold for glassware. After using graphite, ferrous metals can obtain castings with accurate dimensions and smooth surfaces. High, can be used without processing or a small amount of processing, thereby saving a lot of metal. The production of cemented carbide and other powder metallurgy processes usually use graphite materials to make porcelain boats for pressing and sintering. The single crystal silicon crystal growth crucible, regional refining vessel, supporting fixture, induction heater, etc. are all made of high-purity graphite. In addition, graphite can also be used for vacuum smelting graphite insulation boards and substrates,

6. Used in the nuclear energy industry and national defense industry: Graphite has a good neutron moderator for nuclear reactors. Uranium-graphite reactor is currently the most widely used atomic reactor. The decelerating material in the nuclear reactor used as the power should have a high melting point, good stability and corrosion resistance. Graphite can fully meet the above requirements. The graphite used in nuclear reactors has a high purity, and the impurity content should not exceed tens of PPM, especially the boron content should be less than 0.5 PPM. In the defense industry, graphite is also used to manufacture solid fuel rocket nozzles, missile nose cones, aerospace equipment parts, thermal insulation materials and radiation protection materials.

7. Graphite can also prevent boiler fouling. Tests by relevant units have shown that adding a certain amount of graphite powder (approximately 4 to 5 grams per ton of water) can prevent scaling on the boiler surface. In addition, metal chimneys, graphite coatings on roofs, bridges and pipes can prevent corrosion and rust.

8. Graphite can be used as pencil lead, pigment and polishing agent. After special processing, graphite can be made into various special materials for use in related industrial sectors.

9. Electrode

Why can graphite replace copper as electrodes?

In the 1960s, copper was widely used as an electrode material, with a utilization rate of about 90%, while graphite was only about 10%. In the 21st century, more and more users began to choose graphite as the electrode material. In Europe, more than 90% of electrode materials are graphite. Compared with graphite electrodes, copper, the former dominant electrode material, has almost lost its advantages. What caused this huge change? Of course, graphite electrodes have many advantages.

(1) Faster processing speed: In general, the processing speed of graphite can be 2 to 5 times faster than that of copper; the electrical discharge processing speed is 2 to 3 times faster than that of copper;

The material is not easy to deform: it has obvious advantages in the processing of thin-rib electrodes; the softening point of copper is about 1000 degrees, and it is easy to deform when heated; the sublimation temperature of graphite is 3650 degrees; the thermal expansion coefficient is only 1/30 of copper.

(2) Lighter weight: The density of graphite is only 1/5 of copper. When large electrodes are used for EDM, it can effectively reduce the burden of machine tools (EDM); it is more suitable for large molds.

(3) Discharge consumption is small; because the spark oil also contains C atoms, during the electric discharge machining process, the high temperature decomposes the C atoms in the spark oil, and then forms a protective film on the surface of the graphite electrode, which compensates for the loss of the graphite electrode.

(4) No burrs. After the copper electrode is processed, it needs to be manually trimmed to remove the burrs. After the graphite is processed, there is no burr, which saves a lot of cost and makes it easier to realize automated production;

(5) Graphite is easier to grind and polish; since the cutting resistance of graphite is only 1/5 of copper, it is easier to grind and polish by hand;

(6) The cost of materials is lower and the price is more stable; due to the increase in copper prices in recent years, the price of isotropic graphite is now lower than that of copper. With the same volume, Toyo Tanso’s general-purpose graphite products are 30% to 60% lower than copper, the price is more stable, and short-term price fluctuations are small.

It is this unparalleled advantage that graphite has gradually replaced copper as the material of choice for EDM electrodes.

Graphite price

The price of graphite will vary with the production cost, transportation cost, international situation, exchange rate and graphite price.

The supply and demand situation varies randomly. Tanki New Materials Co., Ltd. aims to help various industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full set of customized services. If you are looking for graphite prices

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Graphite supplier

As a global graphite supplier, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced engineering materials. The company has successfully developed a series of powder materials (titanium nitride, silicon nitride, titanium nitride, etc.) high-purity targets, functional ceramics and structural devices, and provides OEM services.