News

• Graphite electrodes: from principle to application

  2024-03-09

  Graphite electrodes, with their unique physical and chemical properties, play a ···

• The application areas of graphite blocks.

  2023-12-22

  1、Smoothness: The smooth function of graphite is similar to molybdenum disulfid···

• Graphite Rotors in Aluminum Degassing: Use and Maintenance

  2023-11-12

  1、Definition:Graphite rotor is a component of aluminum alloy smelting equipment···

• Do you understand the process technology of the main parts of graphite mold processing?

  2023-08-09

  Graphite mold is a very important equipment in the electrical processing industr···

FAQ

• • Q :How to improve the service life of graphite molds?

    Molds can be mainly categorized into three types: cold work dies, plastic molds, and die-casting molds. Each type has its specific focus beyond some common practices. For plastic molds, the use of quenched steel is preferable to pre-hardened steel as it offers a higher lifespan, good polishing characteristics, and strong retention of the polished surface, which significantly enhances the life and quality of the plastic mold. Die-casting molds should be made from mold steel that balances toughness, hot hardness, and high surface strength. Controlling the temperature difference on the surface of the mold cavity during the die-casting process can greatly improve the lifespan of the mold. As for cold work dies, such as stamping dies, selecting the appropriate mold steel according to the material being stamped is crucial. Choosing the wrong steel can lead to short service life and early failure.

    
    

    To improve cold work dies, several aspects can be considered:

    1. Select the appropriate mold steel material. It's especially important to choose the right mold steel based on the thickness and wear pattern of the material being stamped.

    2. Improve the assembly precision of the punch and die.

    3. Enhance the concentricity of the tooling.

    4. Better the surface roughness of the punch and die.

    5. Utilize cryogenic processes with high-precision, multi-station progressive dies or high-speed stamping dies to increase dimensional stability.

    
    

    If toughness is not a consideration, the wear resistance of cold work tool steels can be ranked from high to low as follows: cemented carbide (tungsten carbide) is greater than powder metallurgical high-speed steel, which is greater than sprayed high-speed steel, which is greater than conventional smelted high-speed steel, which is greater than ordinary high-carbon, high-alloy cold work steel.

    
    

  • Q :What are the reasons for the wear of the graphite rotor in the aluminum liquid degasser?

    The wear of the graphite rotor in the aluminum degassing machine is mainly caused by the following two reasons:

    
    

    1. High-temperature Oxidation: Since the degassing chamber cannot be completely sealed, air is present inside. Graphite oxidizes at temperatures above 600°C in the presence of air, forming carbon monoxide and carbon dioxide gases, which gradually deplete the graphite rotor.

    
    

    2. Erosion by Molten Aluminum: The graphite rotor is immersed in the molten aluminum within the degassing chamber, rotating at a speed of 200 to 400 rpm. It stirs the molten aluminum vigorously, which causes erosion and friction against the rotor, gradually wearing away its surface graphite. Additionally, high-temperature oxidation accelerates the erosion caused by the molten aluminum.

    
    

  • Q :What factors affect the lifespan of a graphite crucible?

    The lifespan of a graphite crucible can be affected by several factors including the quality of the crucible, the operating environment, and the method of use.

    
    

    1. Crucible Quality:

    The quality of the graphite crucible is the most important factor affecting its lifespan. High-quality crucibles exhibit excellent purity, density, uniformity, and resistance to oxidation, which allows them to last longer.

    
    

    2. Operating Environment:

    During operation, graphite crucibles are subjected to erosive factors such as high temperatures, oxygen exposure, and slag corrosion. An aggressive environment, characterized by high pressure, high oxygen content, and strong corrosive slag, can significantly reduce the crucible's lifespan.

    
    

    3. Usage Method:

    How the graphite crucible is used also impacts its lifespan. Improper usage such as rapid heating or cooling, or physical impacts can lead to damage and a reduction in useful life.

    
    

    To extend the lifespan of a graphite crucible, the following practices should be considered:

    
    

    - Choose a high-quality graphite crucible.

    - If operating in a harsh environment, adopt appropriate protective measures. For instance, the use of oxidation-resistant coatings or slag-resistant coatings can be beneficial.

    - Use the crucible correctly. Follow the operating procedures strictly to avoid impact and collisions.

    
    

    By implementing the above measures, the lifespan of graphite crucibles can be extended, thereby reducing production costs.

    
    

  • Q :What are the precautions that need to be taken during the production process of graphite crucibles?

    When using a graphite crucible, which is primarily employed for heating experimental materials, particularly solids in a laboratory setting, adherence to stringent production standards is paramount to ensure product quality. Before use, it is important to inspect the crucible for any cracks. It should be preheated to 600°C and dried. The surrounding area must be free of water and extraneous items, and precautions must be taken to prevent the presence of any explosive substances.

    
    

    The materials to be added to the crucible should be preheated and introduced slowly and steadily. The choice of crucible is dependent upon the volume and type of material to be heated, along with its thermal expansion properties. It is critical not to overfill the crucible with the material being heated, as not only is this dangerous, but it can also negatively impact the longevity of the crucible. Additionally, crucibles are often subjected to temperatures up to 4500°C, hence they must be handled cautiously to avoid any hazardous incidents.

    
    

    The fire resistance, chemical stability, hardness, and toughness of the graphite crucible must be tested and considered to ensure its safe and effective use. Selecting the appropriate material is essential for maximizing performance capabilities.

    
    

  • Q :Precautions when using a graphite plate

    Graphite plates have excellent electrical conductivity, high temperature resistance, acid and corrosion resistance, and are easily machined, which is why they're widely used in industries such as metallurgy, chemical engineering, electrochemistry, and mechanical equipment.

    
    

    In industry, graphite is used to make high-temperature crucibles in smelting, protectants for steel ingots, lubricants in mechanical engineering, electrodes, and pencil leads. It's applied in advanced refractory materials and coatings in the metallurgical industry, stabilizers for explosive materials in the military industry, pencil leads in light industry, carbon brushes in the electrical industry, electrodes in the battery industry, and catalysts in the fertilizer industry. Processed flake graphite can be turned into high-tech products such as graphite emulsions, sealing materials, composites, and friction-reducing additives, making it an important non-metallic mineral raw material for various industries.

    
    

    As modern industry keeps advancing, the uses of graphite plates expand, and many manufacturers focus on the lifespan of their products. Several factors affecting the lifespan of graphite plates include:

    
    

    1. Reducing compression impacts, maintaining clean working environments, routinely checking circuits, organizing production under appropriate temperatures, and decreasing oxidation by air.

    
    

    2. Heating in air forms a protective silica layer on the surface that helps to extend the lifespan. To prevent cracking, various coatings have been developed and applied to furnaces operating with different gases.

    
    

    3. The temperature dispersion characteristic is such that newly shipped reflective specifications must be within a 60°C range to be effective. As the plates age, the temperature distribution can increase to 200°C. Specific changes in temperature distribution vary with furnace atmospheres and usage conditions, prompting the need for parallel electrical connections to prevent concentrated loads on high-resistance graphite plates, which can lead to a rapid increase in resistance and reduced lifespan.

    
    

    4. A good working environment is key to lifespan extension. This includes minimizing collisions, keeping the environment clean, scheduling circuit checks, reducing oxidation by air, etc.

    
    

    5. The quality of the processing is a fundamental factor affecting lifespan, so careful manufacturing to meet standards is essential. Uniform treatment, such as impregnation, ensures consistent resistivity and even electrical conductivity, preventing some parts from being intact while others corrode severely.

    
    

    6. Using high-quality graphite materials for manufacturing, such as isostatic graphite, molded graphite, or high-purity graphite, results in longer-lasting graphite plates with improved electroconductivity, bulk density, compression and flexural strength, and resistivity.

    
    

  • Q :flexible graphite material?

    Flexible graphite, also known as expanded graphite, is a non-fibrous material made from treated natural flake graphite. It is transformed into oxidized graphite through the removal of impurities and treatment with strong oxidizing agents such as mixed acid. Upon heating, the oxidized graphite decomposes, releasing carbon dioxide and expanding rapidly, forming a loose, soft, and tough material known as flexible graphite. This material is often pressed into sheet forms and then molded into fillers used for sealing. The main characteristics of flexible graphite include:

    
    

    1. Excellent thermal stability: It maintains its physical properties across an extreme temperature range from -270°C to 3650°C in a non-oxidizing environment and can withstand temperatures of about 600°C in ambient air.

    
    

    2. Superior chemical resistance: Besides being susceptible to corrosion in strongly oxidizing environments (such as concentrated sulfuric and nitric acids), flexible graphite has a high level of resistance to other acids, bases, and solvents.

    
    

    3. Exceptional self-lubricating properties: Due to the characteristic interlayer structure, flexible graphite can slide easily under applied force, similar to natural graphite, exhibiting good lubricity and reduced wear properties with a low coefficient of friction.

    
    

    4. High resilience: Flexible graphite can accommodate eccentricity and radial runout of shafts or bushings due to manufacturing and installation inconsistencies. It still fills gaps effectively even if minor cracks appear, ensuring a tight seal to prevent leakage.

    
    

  • Q :Graphite electrodes are used for what?

    Graphite is known for its low electrode loss and high discharge machining removal rate, making it an outstanding electrode material. It is gradually replacing copper electrodes, and some complex-shaped electrodes cannot be made of copper, hence the application of graphite electrodes is becoming more widespread. The processing of graphite electrodes often opts for CNC graphite engraving mills for rapid machining. However, graphite machining does come with its challenges:

    
    

    1. Long production cycles: The production cycle for ordinary power graphite electrodes is about 45 days. Ultra-high power graphite electrodes take over 70 days, and those that require multiple impregnations have even longer production cycles.

    
    

    2. High energy consumption: Producing 1 ton of ordinary power graphite electrodes consumes about 6000 kWh of electricity and thousands of cubic meters of gas or natural gas, as well as about 1 ton of metallurgical coke granules and coke powder.

    
    

    3. Numerous production steps: Production involves processes such as raw material calcination, crushing and grinding, batching, kneading, molding, baking, impregnation, graphitization, and machining. The production requires many specialized machines and kilns with special structures, resulting in large investment and a long pay-back period.

    
    

    4. Dust and harmful gases: A significant amount of dust and harmful gases are generated in the production process, necessitating effective ventilation, dust reduction, and measures to eliminate harmful gases for environmental protection.

    
    

    5. Raw material issues: The carbonaceous raw materials like petroleum coke and coal tar pitch, which are by-products from oil refining and coal chemical industries, do not always have guaranteed quality and stability. This is especially true for materials like needle coke and modified impregnating pitch required for high and ultra-high power graphite electrode manufacturing, urgently requiring the attention and cooperation of China's petroleum and coal chemical processing enterprises.

    
    

    As for CNC machines dedicated to graphite, even though graphite is a material that is relatively easy to machine, it causes significant tool wear, and the dust generated during the processing can not only wear out the internal components of the machine (such as ball screws and guideways) but can also pose health risks to operators. Therefore, machining of graphite materials requires equipment with good sealing performance. CNC graphite milling machines have excellent sealing, equipped with multiple protective measures tailored to the characteristics of graphite machining, including multi-layer protective shields installed on guideways to effectively protect ball screws and guideways. They are also equipped with high-efficiency dust collection systems to capture the graphite dust effectively. Additionally, the cast structures of these machines are stable, they offer high precision in machining, and have a long service life, meeting the demands of heavy-duty or high-speed machining.

    
    

  • Q :What is the role of graphite in graphite carbon rods?

    So what is the role of graphite in graphite rods? Next, will introduce you one by one.

    
    

    1、 Graphite can prevent boiler scaling, graphite can be coated on metal chimney, roof, bridge, pipeline can be anti-corrosion and rust proof.

    
    

    2、 As conductive materials: used in the electrical industry as the anode of electrode, brush, carbon rod, carbon tube, mercury positive current device, graphite washer, telephone parts, coating of television picture tube, etc.

    
    

    3、 As wear-resistant and smooth data: graphite is often used as a smooth agent in the mechanical industry. The smooth oil can not be used in high speed, high temperature and high pressure, while graphite wear-resistant data can be used at a high sliding speed at 200-2000 ℃ without smooth oil. Many equipment transporting corrosion media, graphite materials are widely used to make piston cup, sealing ring and bearing. They do not need to add smooth oil when they work. Graphite milk is also an outstanding smooth agent in many metal processing (drawing wire and drawing pipe).

    
    

    4、 As casting, sand turning, die pressing and high temperature metallurgy data: because of the small thermal expansion coefficient of graphite and the ability to withstand the change of rapid cold and rapid heat, it can be used as a mold for glass ware. After using graphite, ferrous metal can be used to obtain the casting scale accurately, and the surface finish rate is high, and it can be used without processing or processing, so many metals are saved. The powder metallurgy process such as hard alloy is produced. The ceramic boat for pressing and sintering is usually made from graphite materials. Crystal growth crucible, regional quintessence container, support fixture, induction heater, etc. of monocrystalline silicon are all processed with high purity graphite. In addition, graphite can be used as heat insulation plate and base of vacuum smelting, high temperature resistance furnace tube, rod, plate, lattice shed and other elements.

    
    

    5、 As fire resistant materials: graphite and its products have the properties of high temperature resistance and high strength. It is used to make graphite crucible in metallurgical industry. Graphite is used as the protective agent of ingot and lining of metallurgical furnace in steel making.

    
    

    6、 Graphite can be used as pencil core, pigment and polishing agent.

    
    

    7、 Electrode: why graphite can replace copper as electrode.

    
    

    8、 Graphite has excellent chemical stability. Through the special processing of graphite, with the characteristics of corrosion resistance, good heat conductivity and low permeability, many of them are used to make heat exchanger, reverberation tank, condenser, incinerator, absorption tower, cooler, heater, filter and pump equipment. It is widely used in petrochemical, hydrometallurgy, acid-base production, synthetic fiber, paper industry and other industries, which can save a lot of metal data.

    
    

    Because the carbon rod is used at high temperature, it is easy to conduct excellent chemical stability. It has been widely used in national defense, machinery, metallurgy, chemical industry, casting, non-ferrous alloy, light and other categories, especially black carbon rods, and also used as ceramics, semiconductors, medicine, environmental protection, laboratory analysis and other categories, and has become the most widely used non-metallic materials. When cutting steel, it is not necessary to use flammable and explosive gas like oxyacetylene flame cutting, which has low cost and safe operation. It can be used to process many kinds of metals which can not be processed by gas cutting, such as cast iron, stainless steel, copper, aluminum, etc. with high efficiency and ideal results.

  • Q :Under what circumstances do graphite parts need to be replaced?

    1. Strictly follow the operating procedures, such as heating, melting, remelting and furnace shutdown, to protect the graphite parts. After each furnace is disassembled, the graphite accessories should be carefully cleaned, the seed crystal and the graphite thermal field accessories should be carefully checked, and the specific records should be made.

    
    

    2. If part of the crucible is damaged (for example, three pieces are broken and one piece is broken) but it has not reached the life limit, it can be put together or replaced (if there are only a few heats of new three piece crucible, the workshop supervisor will decide whether to use it or not after judging it, make up a set of crucible that can be used and can be put together, and seal and keep the crucible that can be used but not used for the time being). It is suggested that the sealed storage should be used in the furnace of purification when it is used again.

    
    

    3. Every time the furnace is disassembled, the oxide in the thermal field shall be sorted out, and the siliconizing on the graphite parts shall be cleaned up. The guide tube and insulation cover shall be carefully cleaned to prevent impurities from polluting the raw materials. In addition to personal safety, take care to handle graphite parts with care.

    
    

    4. In principle, those whose lifespan has reached the replacement deadline need to be replaced (or let experienced people identify them and decide whether they can continue to use them). For those who are not used for the time being, they should be sealed in plastic bags, packed in cartons, marked with heat number, heat number, reason for replacement, source and date, and kept properly

    
    

    5. Check the graphite accessories for cracks, especially the graphite crucible, graphite tray and graphite crucible rod. If there are cracks, immediately report to the workshop supervisor and replace them. Judge or report to the workshop supervisor where there is silicon. Before the five heats are used to estimate the service life, the shift leader is responsible for checking and checking. After the five heats before the estimated service life are used, the workshop supervisor is responsible for checking and checking.

    
    

    6. After the service life of graphite accessories is expired, the graphite accessories (graphite tray, crucible rod, graphite crucible) that may cause heavy losses after overdue use shall be removed and replaced with new products. The replaced graphite accessories shall be sealed up, and then be handled after joint review by single crystal workshop, technology department and production department. Other accessories such as heater, heat preservation cylinder, guide cylinder, etc. shall be handled carefully Check to see if there are small cracks and defects. In principle, these graphite accessories can be used continuously without the above defects. It is necessary to make specific records about the graphite thermal field accessories that present the closed furnace.

    
    

    7. Record the details of the graphite thermal field accessories. The graphite accessories with problems should be recorded and put into the designated address to prevent mixing.

  • Q :Why is graphite device damaged during graphite processing?

    First, we can understand the relevant characteristics of graphite. 1. high temperature resistance, high melting point of graphite, 3850 ℃ in vacuum, increase at low pressure, and increase temperature of 2200 degrees. Unlike general data, when the temperature increases, graphite not only does not soften, but increases its strength, but increases its tensile strength by twice when it is 2500 ℃. 2. special thermal shock resistance, the thermal expansion of graphite is anisotropic, so the micro expansion coefficient is not large, and the volume of graphite is not changed under the condition of sudden temperature change. In addition, it has excellent thermal conductivity, so the thermal shock resistance of graphite is outstanding. As mentioned above, graphite parts should be able to work stably at high temperature for a long time.

    
    

    In general, compared with other graphite equipment such as heat preservation cover and heater, the flap pot is the same data, same manufacturer and same working environment. Why is the life of the pot far lower than that of the heat preservation cover and heater?

    
    

    The main reason for cracking of the triple pot is quartz crucible. 1. because the density of molten silicon is larger than solid silicon, the bottom material of the pot will break the quartz crucible during cooling, and the quartz crucible is attached to the triple valve pot. When the stress produced by the cracking of the quartz crucible is greater than the stress of the triple valve crucible, the triple valve crucible will crack. This is to say, if the bottom material of the pot is too much, the triple valve pot will be broken. This is to say, if the bottom material of the pot is too much, the triple valve crucible will be broken The cause of the pot. 2. if the heating time is too long, the quality of the quartz crucible is not over-standard and the raw material pH is not up to the requirements, silicon leakage and silicon permeability will be caused. After the gap between the fused silicon infiltrated into the three valve pot is cooled, one is to break the three-way pot, the other is to make the three-way pot bond with each other, and make it separate from each other during furnace cleaning, which can cause cracking. 3. in the heating process, only the heat source of the three-way pot comes from two aspects: one is the radiation of the heater, the other is from the conduction of the quartz crucible, which leads to the uneven heating of the three-way pot, which expands in some directions, shortens in other directions, and then causes the triple flap pot to crack.

    
    

    The components of the heat field, such as heater, three-way pot, graphite holder and thermal screen, are all made of graphite. In the process of production, often encounter the phenomenon of heating equipment damage, so what is the reason for the damage of graphite equipment, what measures should be taken to extend the life of graphite equipment? The damage of graphite equipment is mainly caused by human and deterioration. As long as the human side strengthens the management and strengthens the staff's defense awareness, the loss can be reduced to the lowest point. Deterioration is the first thing to discuss here.

  • Q :How does graphite mattress produce negative oxygen ion after heating?

    Graphite is a crystalline deposit of carbonaceous elements, and its crystal framework is hexagonal layered structure. The distance between each mesh layer is 340pm, and the distance between carbon atoms in the same mesh layer is 142pm;. It belongs to hexagonal crystal system with perfect lamellar cleavage. The cleavage surface is mainly composed of molecular bonds and has weak attraction to molecules, so it has good natural floatability.

    
    

    Graphite products maintain the original chemical characteristics of flake graphite, and also have strong self-lubricating properties. The specially processed graphite has the characteristics of corrosion resistance, good thermal conductivity and low permeability. It is widely used in making heat exchangers, reaction tanks, condensers, incinerators, absorption towers, coolers, heaters, filters, pumps and other equipment. These equipment are used in petrochemical, hydrometallurgy, acid and alkali production, synthetic fiber, paper and other industrial sectors, which can save a lot of metal materials. With the continuous development of science and technology, people have developed many new uses for graphite. Flexible graphite products, also known as expanded graphite, is a new kind of graphite products. In addition to the characteristics of natural graphite, it also has special flexibility and elasticity. Therefore, it is an ideal sealing material. It is widely used in petrochemical, atomic energy and other industrial fields. The world market demand is increasing year by year.

    
    

    Graphite products, especially graphite mattresses, can produce negative oxygen ions after heating, activate the surrounding articles, maintain human health, effectively prevent aging, and make skin full of luster and elasticity. The pan and pot made of graphite are heated quickly, and the cooked food is heated evenly from the inside to the outside. The heating time is short. It not only tastes pure, but also can lock the original nutrition of the food. Crucibles and related products are made of graphite. They are shaped and fire-resistant crucibles and related products. They have high fire resistance and low thermal expansion. In the process of melting metal, they are also stable when they are moistened and washed by metal. They have excellent thermal shock stability and excellent conductivity at high temperature. Therefore, graphite crucibles and related products are widely used in the process of direct melting metal.

    
    

    At room temperature, the chemical properties of carbon are relatively stable, insoluble in water, dilute acid, water, etc

    
    

    Dilute alkali and organic solvent; react with oxygen at high temperature to produce carbon dioxide or carbon monoxide; in halogen, as long as fluorine can react directly with elemental carbon; under heating, elemental carbon is easily oxidized by acid; at high temperature, carbon can react with many metals to form metal carbides. Carbon is reductive and can temper metals at high temperatures. In addition, recent studies have found that graphite can be dissolved by chlorosulfonic acid to form a chlorosulfonic acid "solution" of monolayer graphene.