English name: graphite Graphite crystals are in the form of scales; they are modified under high-intensity pressure and are divided into large scales and fine scales. This type of graphite ore is characterized by low grade, generally between 2 and 3%, or between 100 and 25%. It is one of the best floatable ores in nature, and high-grade graphite concentrate can be obtained through multiple grinding and multiple selection. The floatability, lubricity, and plasticity of this type of graphite are superior to other types of graphite; therefore, its industrial value is the largest. Hidden quality graphite is also called amorphous graphite or earthy graphite. The crystal diameter of this graphite is generally less than 1 micron, and the specific surface area ranges from 1-5m2 / g (automatic F-Sorb 2400 specific surface area meter BET method test), It is a collection of microcrystalline graphite, and the crystal form can only be seen under an electron microscope. This type of graphite is characterized by a soil-like surface, lack of gloss, and poor lubricity. High grade. Generally 60 ～ 80%. A few are over 90%. The selectivity of ore is poor. Wheel For Duffel Bag,Detachable Luggage Tag,Detachable Trolley Wheels,Plastic Trolley Wheels GUANGDONG SUNDES LUGGAGE ACCESSORY TECHNOLOGIES CO.,LTD , https://www.sundes-global.com
Molecular formula: C
Molecular weight: 12.01
CAS login number: 7782-42-5
EINECS login number: 231-955-3
Graphite is a crystalline mineral of carbonaceous elements, and its crystal lattice is a hexagonal layered structure. The distance between each mesh layer is 3.40 people, and the spacing of carbon atoms in the same mesh layer is 1.42A. It is a hexagonal crystal system with complete layered cleavage. The cleavage surface is dominated by molecular bonds and has a weak attraction to molecules, so its natural floatability is very good.
Graphite and diamond, carbon 60, carbon nanotubes, etc. are all simple elements of carbon, and they are allotropes.
Laixi City, Shandong Province, is one of the important graphite producing areas in China. The proven reserves of graphite are 6.811 million tons, and the reserves are now 639.93 million tons.
Graphite is soft, black and gray; greasy, can pollute paper. The hardness is 1 ~ 2, and the hardness can increase to 3 ~ 5 with the increase of impurities in the vertical direction. The specific gravity is 1.9 ～ 2.3. The specific surface area range is concentrated in 1-20m2 / g (automatic F-Sorb 2400 specific surface area instrument BET method test). Under the condition of oxygen isolation, its melting point is above 3000 ℃, which is one of the most temperature-resistant minerals.
There is no pure graphite in nature, which often contains impurities such as SiO2, Al2O3, FeO, CaO, P2O5, CuO and so on. These impurities often appear in the form of quartz, pyrite, carbonate and other minerals. In addition, there are water, asphalt, CO2, H2, CH4, N2 and other gas parts. Therefore, in addition to the fixed carbon content, the analysis of graphite must also determine the content of volatile matter and ash.
The technological characteristics of graphite mainly depend on its crystalline form. Graphite minerals with different crystalline forms have different industrial values ​​and uses. In industry, natural graphite is divided into three types according to different crystal forms.
1. Dense crystalline graphite Dense crystalline graphite is also called massive graphite. This type of graphite crystal is clearly visible to the naked eye. The particle diameter is greater than 0.1 mm, the specific surface area range is concentrated in 0.1-1m2 / g (automatic F-Sorb 2400 specific surface area instrument BET method test), the crystal arrangement is disordered, showing a dense block structure. This type: graphite is characterized by a high grade, with a general carbon content of 60 to 65%, and sometimes 80 to 98%, but its plasticity and greasiness are not as good as flake graphite. The study of the specific surface area of ​​graphite is very important. Only the results of the detection of the specific surface area of ​​graphite are real and reliable when the results are detected by the BET method. There are many instruments in China that can only be tested by the direct comparison method. Now it has been eliminated in China. At present, the multi-point BET method is used uniformly for the specific surface area testing at home and abroad. The specific surface area measurement standards developed at home and abroad are based on the BET test method. Please refer to China's national standard (GB / T 19587-2004)-Gas adsorption BET principle Method for determining the specific surface area of ​​solid materials. The measurement of specific surface area is actually a time-consuming task. Due to the different adsorption capacity of the sample, the test of some samples may take a whole day. If the test process is not fully automated, then the tester ca n’t leave at all times. A high degree of concentration, observing the instrument panel, manipulating the knob, and a little inattention will lead to the failure of the test process, which will waste a lot of precious time of the tester. Only truly fully automated intelligent specific surface area tester products can meet the international standards of the test instrument industry. All similar international products are fully automated. Manually operated instruments have long been eliminated abroad. A truly fully automated intelligent specific surface area analyzer product frees testers from repeated mechanical operations, greatly reducing their work intensity, training is simple, and working efficiency is improved. The truly fully automated intelligent specific surface area analyzer product greatly reduces errors caused by human operations and improves test accuracy. Among several domestic manufacturers of specific surface area analyzers, only the F-Sorb 2400 specific surface area analyzer of Beijing Jinyi Spectrum Technology Co., Ltd. is an instrument that can truly realize the detection function of the BET method (both with direct comparison method), and the more important Beijing Gold F-Sorb 2400 specific surface area analyzer is the only fully automated and intelligent specific surface area detection equipment in China. Its test results are highly consistent with international standards, and its stability is also very good. At the same time, it reduces human errors. Improve the accuracy of test results.
2. Flake graphite
Flake graphite
3. Cryptocrystalline graphite
Cryptocrystalline graphite
Graphite is widely used in industry, and it is used in almost every industry. Artificial graphite is commonly used in industry, that is, special graphite. According to its molding method, it can be divided into the following types.
1. Isostatic graphite. That is what many people call the three-high graphite, but not the three-high graphite is equal static pressure.
2. Molded graphite
3. Extruded graphite, mostly electrode material.
According to the particle size of graphite, it can also be divided into: detailed graphite, medium and coarse graphite (the general particle size is about 0.8mm), and electrode graphite (2-4mm).
Due to its special structure, graphite has the following special properties:
1) High temperature resistant type: The melting point of graphite is 3850 ± 50 ℃, and the boiling point is 4250 ℃. Even if it is burned by ultra-high temperature arc, the weight loss is very small and the coefficient of thermal expansion is also very small. The strength of graphite strengthens with increasing temperature. At 2000 ℃, the strength of graphite doubles.
2) Electrical and thermal conductivity: The electrical conductivity of graphite is one hundred times higher than that of ordinary non-metallic ores. Thermal conductivity exceeds metal materials such as steel, iron, and lead. The thermal conductivity decreases with increasing temperature. Even at extremely high temperatures, graphite becomes an insulator. Graphite can conduct electricity because each carbon atom in graphite only forms 3 covalent bonds with other carbon atoms, and each carbon atom still retains 1 free electron to transfer charge.
3) Lubricity: The lubricating performance of graphite depends on the size of graphite flakes. The larger the flakes, the smaller the friction coefficient and the better the lubricating performance.
4) Chemical stability: Graphite has good chemical stability at normal temperature, and is resistant to acid, alkali and organic solvents.
5) Plasticity: Graphite has good toughness and can be rolled into a very thin sheet.
6) Thermal shock resistance: When used at room temperature, graphite can withstand the drastic change of temperature without damage. When the temperature changes suddenly, the volume of graphite does not change much and there will be no cracks.
Name origin: derived from the Greek "graphein", meaning "to write". Named by German chemist and mineralogist AG Werner in 1789;
Chemical composition: those with pure ingredients are few and often contain various impurities;
Category: natural elements-non-metallic elements-carbon family crystal system and space group: hexagonal crystal system, P63 / mmm;
Cell parameters: a0 = 0.246nm, c0 = 0.670nm;
Morphology: Single crystals are often in the form of sheets or plates, but intact are rare. The aggregate is usually scaly, massive and earthy;
Color: iron black;
Streak: bright black Transparency: opaque gloss: semi-metallic gloss Hardness: 1-2
Cleavage and fracture: parallel cleavage is very complete;
Specific gravity: 2.21-2.26g / cm3
Specific surface area: 5-10m2 / g (automatic F-Sorb 2400 specific surface area instrument BET method test),
Other properties: The sheet is flexible, slippery, easy to stain hands, and has good conductivity;
Appraisal characteristics: Iron black, low hardness, a group of extremely cleaved, slippery and dyed hands;
Causes and occurrence: Graphite is formed at high temperatures. The most widely distributed is graphite metamorphic deposits, which are formed by sedimentary rocks rich in organic matter or carbonaceous through regional metamorphism;
Main uses: Graphite is widely used in industry. It is used to make high-temperature crucibles for smelting, lubricants for the mechanical industry, electrodes and pencil cores; it is widely used for the stabilization of high-grade refractory materials and coatings in the metallurgical industry, and military industrial pyrotechnic materials Agent, pencil lead for light industry, carbon brush for electrical industry, electrode for battery industry, catalyst for fertilizer industry, etc. After deep processing, flake graphite can produce high-tech products such as graphite emulsion, graphite sealing materials and composite materials, graphite products, and graphite friction-reducing additives. It has become an important new non-metallic mineral raw material graphite in various industrial sectors:
With the continuous development of science and technology, people have developed many new uses for graphite.
Flexible graphite products. Flexible graphite, also known as expanded graphite, is a new graphite product developed in the 1980s.
In the United States, it successfully researched flexible graphite sealing materials and solved the leakage problem of atomic energy valves. Subsequently, Germany, Japan and France also began to develop and produce. In addition to the characteristics of natural graphite, this product also has special flexibility and elasticity.
Therefore, it is an ideal sealing material. Widely used in petrochemical industry, atomic energy and other industrial fields. The demand in the international market is increasing year by year.
Famous places of origin: New York Ticonderoga, Madagascar and Ceylon, China's largest place of origin is Liu Mao in Jixi City, Heilongjiang.
Diamonds are "flying" out of graphite powder. When people mention diamonds, people will associate with the dazzling and dazzling scene, which shines with the owner's activities. But because of its expensive price, most people can only be discouraged. Nonetheless, people still yearn for diamonds. Do you know what a diamond is? Its chemical composition is carbon (C), and natural diamonds are called diamonds after being polished by diamonds. Natural diamonds are very scarce. There are only two diamonds weighing more than 1,000 carats (1 gram = 5 carats) in the world, and more than 400 carats. There are only 158.786 carats in China. "Changlin Diamond". Things are rare, because natural diamonds that can be used as "diamonds" are very rare, people want to replace them with "artificial" diamonds, which naturally comes to mind the diamond's "twin" brother-graphite.
The chemical composition of diamond and graphite are both carbon (C), called "allotropes". From this name, we can know that they have the same "quality", but the "form" or "sex" is different, and there is a world difference. Diamond is currently the hardest substance, while graphite is one of the softest substances.
The hardness of graphite and diamond is so different, but people still hope to obtain diamond by artificial synthesis, because the graphite (carbon) reserves in nature are very rich. But it is not so easy to change the carbon in graphite into carbon arranged like diamonds. Graphite can be converted into diamond by using metal iron, cobalt, nickel, etc. as catalysts at 50,000 to 60,000 atmospheres ((5-6) × 103MPa) and high temperature of 1000 to 2000 degrees Celsius.
At present, more than a dozen countries in the world (including China) have synthesized diamonds. However, because of its fine particles, this diamond is mainly used as an abrasive, as a drill bit for cutting and drilling in geology and petroleum. At present, 80% of the world's diamond consumption is mainly used in industry, and its output far exceeds that of natural diamond.
The initially synthesized diamond particles are black, 0.5 mm in size, and weigh about 0.1 carat (diamonds used for gemstones generally cannot be smaller than 0.1 carat). At present, the large-grain diamonds developed by our country are more than 3mm, and the United States, Japan, etc. have made more than 6.1 carats of diamonds. We say that diamonds have "flyed" out of graphite, and gem-quality synthetic diamonds will also be supplied to the market in the near future.
How can graphite replace copper?
In the 1960s, copper was widely used as an electrode material, with a utilization rate of about 90% and graphite of only about 10%. In the 21st century, more and more users began to choose graphite as an electrode material. The electrode material is graphite. Copper, the electrode material that once dominated, its advantages almost disappeared compared to graphite electrodes. What caused this dramatic change? Of course, the many advantages of graphite electrodes.
(1) Faster processing speed: under normal circumstances, the mechanical processing speed of graphite can be 2 to 5 times faster than copper; and the discharge processing speed is 2 to 3 times faster than copper;
The material is less likely to deform: it has obvious advantages in the processing of thin rib electrodes; the softening point of copper is about 1000 degrees, which is easy to deform due to heat; the sublimation temperature of graphite is 3650 degrees; the coefficient of thermal expansion is only 1/30 of copper.
(2) Lighter weight: The density of graphite is only 1/5 of that of copper. When large electrodes are used for electrical discharge machining, the burden of machine tools (EDM) can be effectively reduced; it is more suitable for applications on large molds.
(3) The discharge consumption is smaller; because the spark oil also contains C atoms, during discharge machining, the high temperature causes the C atoms in the spark oil to be decomposed, which in turn forms a protective film on the surface of the graphite electrode, which compensates for the graphite electrode ’s loss.
(4) No burrs; copper electrodes need to be manually trimmed to remove burrs after the processing is completed, and graphite processing has no burrs, which saves a lot of costs, and it is easier to realize automated production;
(5) Graphite is easier to grind and polish; because the cutting resistance of graphite is only 1/5 of copper, it is easier to grind and polish by hand;
(6) The material cost 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. Under the same volume, the price of Toyo Carbon's universal graphite products is 30% lower than that of copper. % ～ 60%, and the price is more stable, the short-term price fluctuation is very small.
It is this unparalleled advantage that graphite gradually replaces copper as the material of choice for EDM electrodes