In large-scale industrial production, it is difficult to reach the high temperature of 2000. However, in the process of high-temperature heat treatment and transformation, when the temperature reaches 2000 ℃, the thermal conductivity and conductivity of carbon change greatly. At this temperature, it has been able to achieve the good characteristics of graphite, with good thermal conductivity and conductivity. Therefore, at 2500 ℃, the heat-treated artificial graphite has 16 times higher thermal conductivity and 4 times higher electrical conductivity than the carbon material, and its structure is more lubricating and easier to process than the carbon material.
In this way, the main technical properties of the artificial graphite can be similar to that of the natural graphite artificial graphite. There are three methods, namely extrusion molding, ramming molding and balanced compression molding. Different molding methods affect the direction of mechanical properties of graphite. Therefore, different materials of graphite products with different forming methods should be used to make different purpose graphite equipment. One cubic meter of sand weighs more than one cubic meter of stone. Because the gap is smaller, the smaller the particle size, the higher the density of graphite products, and the better the strength and other indicators.
Graphite electrode is easy to process, and the processing speed is faster than copper electrode. For example, when using milling technology to process graphite, its processing speed is 2-3 times faster than that of other metals, and no additional manual treatment is needed, while copper electrode needs manual grinding. Similarly, if high-speed graphite products processing center is used to make electrodes, the speed will be faster, the efficiency will be higher, and there will be no dust problem. In these processes, choosing the right hardness tool and graphite can reduce the wear loss of the tool and the damage of the electrode. If the milling time of graphite electrode is compared with that of copper electrode, graphite is 67% faster than that of copper electrode. In general, the machining speed of graphite electrode is 58% faster than that of copper electrode. In this way, the processing time is greatly reduced, and the manufacturing cost is also reduced. Therefore, our purchasing personnel need to hold many models of graphite products in the market, look at the bumpy component, the color and other aspects to see good results, because now the technology is more advanced, which is also helpful to improve the performance of the products.
Graphite & Carbon Electrodes is mainly made of petroleum coke and needle coke as raw materials, coal tar pitch as binder, calcined, proportioned, kneaded, pressed, roasted, graphitized and machined. It is a conductor that releases electric energy in the form of electric arc to heat and melt the furnace charge. According to its quality index, it can be divided into ordinary power graphite electrode, high power graphite electrode and ultra-high power stone Ink electrode.
The main raw material of Graphite & Carbon Electrodes production is petroleum coke. A small amount of pitch coke can be added to ordinary power graphite electrode. The sulfur content of petroleum coke and pitch coke cannot exceed 0.5%. Needle coke is also needed to produce high power or ultra-high power graphite electrode. The main raw material for aluminum anode production is petroleum coke, and the sulfur content is controlled to be no more than 1.5% – 2%. Petroleum coke and asphalt coke shall meet the relevant national quality standards.
1.Problems of graphene dispersion
Graphene has a single complete six membered ring structure, so there is a strong intermolecular force between graphene molecules, and the layers are easy to stack together, resulting in agglomeration. The surface of graphene is stable and inert, which makes it difficult to dissolve in basic solvents, and it is very difficult to functionally composite with other materials, which has become a huge problem in the application of graphene.
2.Countermeasures to the problem of decentralization
In order to improve the dispersion effect of graphene, the material with better dispersion effect is selected, which is called surfactant. According to different surfactants and basic solvents, the optimal dispersion of graphene is also different. Fluorescence microscope and ultraviolet visible spectrophotometer were used to determine the optimal amount of graphene.
When the well dispersed graphene is mixed into the matrix asphalt, it is necessary to intercalate the graphene and asphalt to reflect the physical adsorption capacity brought by the huge specific surface area of graphene. The intercalation effect of the mixture of graphene and asphalt can only be produced under the cavitation effect of ultrasonic instrument, sound flow effect and uniform dispersion effect of emulsified asphalt high-speed shear, Comprehensively improve the performance of asphalt road.
3.Study on Preparation Technology
The mixture of matrix asphalt and graphene was treated by emulsified asphalt high-speed shear and ultrasonic cell crusher. Using uniform design method, the asphalt treatment capacity, shear time, rotation number, asphalt temperature during shear, time and power of high-intensity ultrasound, graphene content, surfactant and basic solvent content were taken as the main influencing factors, and the three indexes, anti rutting factor and creep recovery rate were taken as response values. The model was established by using DPS and 1stOpt mathematical statistics software, The mixture ratio and preparation process parameters of graphene modified asphalt were obtained.
Lithium ion battery is the most popular circulating battery because of its high voltage and high specific energy. Graphene is a unique nano material, with unique network structure, multi-stage pore structure and excellent electrical properties, which can greatly improve the battery capacity and has a broad economic prospect.
MIT has developed a new flexible and transparent solar cell, which is realized by depositing a single atom thick graphene layer on a solar cell, which will not damage nearby organic materials. Developers of transparent solar cells usually rely on expensive brittle electrodes, which break easily when devices bend. Graphene can make it possible to use a truly flexible, low-cost, transparent solar cell.
In order to meet the needs of intelligent power grid, mobile communication and electric vehicle, the power lithium battery Engineering Laboratory of Ningbo Institute of materials has developed a kilowatt grade aluminum air battery power generation system based on graphene air cathode. Its energy density is high, its capacity and output power are greatly improved, and graphene has great potential in the field of battery.
In coastal cities and industrial intensive areas, industrial waste gas and coastal air have a serious corrosion effect on the surface of transmission iron of national grid, which seriously endangers the power transmission safety. Graphene is used in corrosion resistant coating, and has achieved remarkable results. Graphene and organic materials are combined to form functional graphene polymer composites, which solve the problems:
(1) The conductivity of the conductor part of the cable is not consistent with the working strength;
(2) The outer layer of the cable is not conductive, which is easy to cause safety hazards and lead to power grid safety accidents;
(3) To improve the capacity and working intensity of DC energy storage equipment, and make contribution to the establishment of clean and efficient power industry.
1. Graphene raw materials: natural graphite, artificial graphite, expanded graphite, such as graphite raw materials finishing and equipment.
2. Graphene powder materials: oxidation and reduction of large-scale preparation of graphene powder, preparation of graphene nano-flakes or graphene flakes, graphene quantum dots, oxidized graphene solutions, graphene solutions, activated graphene, porous graphene, functional graphene, oxidized graphite sheets, graphene sponges, graphene aerogel, etc. by liquid phase stripping;
3. Graphite powder preparation equipment, graphite powder microwave processing equipment, graphite powder heat treatment equipment, graphene powder packaging equipment, coating equipment.
4. Graphene Film: copper/Nickel/Platinum surface CVD preparation of monolayer and multilayer graphene, graphene transfer technology, graphene electrochemical stripping, graphene film doping, graphene thin film growth CVD equipment, graphene membrane transfer equipment, graphene film low-temperature growth equipment.
5. Graphene testing standard equipment: Raman, OM, AFM, SEM, XPS, ICP, Vis, TEM, BET, laser-guided calorimeter, powder conductivity measurement equipment, laser particle size analyzer, electrochemical workstation, fluorescence spectrum, coating performance testing. Testing service agencies, graphene products standardization agency.
Graphene is one of the most important compounds in the world ² The hybrid connected carbon atoms are closely packed to form a single layer of two-dimensional honeycomb lattice structure. Graphene has excellent optical, electrical and mechanical properties. It has important application prospects in materials science, micro nano processing, energy, biomedicine and drug delivery. It is considered to be a revolutionary material in the future.
Andre Geim and Konstantin Novoselov, physicists at the University of Manchester in the UK, successfully separated graphene from graphite by micromechanical stripping method, so they jointly won the 2010 Nobel prize in physics. The common methods of graphene powder production are mechanical exfoliation, redox, SiC epitaxial growth, and the film production method is chemical vapor deposition (CVD).
On June 27, 2018, China graphene industry technology innovation strategic alliance released the new group standard named guide for products containing graphene materials. This standard specifies the nomenclature of new products related to graphene materials.
With the development of science and technology, human resources will be used less and such as oil, forests, all kinds of minerals, with a little less than a day. These resources are mined, mined, and much larger than the growth of resources, so resources will be used less and more expensive. The development and research of new energy is essential.
In the coming decades, graphite and water can also be used to generate electricity. The two common materials, the general part of the combination of large natural materials-“graphite + water” can create energy storage systems, produce comparable lithium-ion battery storage effect, and in a matter of seconds full of electricity, with almost infinite long service life. The principle of graphite + graphite water energy storage is to use charge to realize the mass of electric energy by the orderly accumulation of the surface of conductive carbon atoms in the whole interface. Ultra-fast storage and release of graphite, a new type of storage device based on “graphite + water” gels can be recharged in a matter of seconds. New science will be used in the human world to erect a new inner monument for the development of mankind.
The French researchers reported that the more irregular carbon materials used to make supercapacitor electrodes, the greater the capacitance of the supercapacitor is and the stronger the ability to withstand high pressure.
Supercapacitor is a new type of energy storage device, which has the advantages of short charging time, high output power, long life and so on, which can be used for braking energy recovery system of vehicles. Its working principle is based on the interaction between the electrode and the positive anion in the electrolyte, the greater the electrode surface area and the stronger the interaction between the positive and negative ions, the greater the capacitance.
The French National Research Center and the University of Orleans researchers used NMR spectroscopy to quantify the electrostatic effects of electrodes and positive negative ions, the results found that the more irregular structure of carbon electrode materials, the greater the capacitance of the super capacitor, the higher the withstanding capacity of high pressure.
The main raw material of graphite crucible is crystalline natural graphite. Because it retains all kinds of physical and chemical properties of natural graphite. It has good thermal conductivity and high temperature resistance, in the process of high-temperature use, the coefficient of thermal expansion is small, and it has a certain strain-resisting function for hot and cold. Acid, alkaline solution of strong erosion resistance, with excellent chemical instability. The type of crucible has more specifications, graphite powder in the application is not subject to production scale, batch size and smelting material varieties of restrictions, can be arbitrary choice, the combination of strong, and can guarantee the purity of the melted material.
First, after use to place dry place, avoid rainwater intrusion, before use must be slow bake to 500 degrees Celsius before use.
Second, should be fed according to the capacity of the crucible, avoid squeezing too tightly, so as to avoid the metal heat expansion cracking crucible.
Third, out of molten metal, it is best to scoop out with a spoon, as far as possible with a caliper, if the tool with calipers and other tools should be consistent with the shape of the crucible to avoid local force too large and shorten the service life.
Graphite has the following special properties because of its special structure:
1. High temperature resistance: Graphite Melting point is 3850±50℃, boiling point is 4,250 ℃, even after the ultra-high temperature arc burning, the loss of weight is very small, the coefficient of thermal expansion is also very small. The graphite strength increased with the increase of temperature, and the graphite strength was 1 time times when 2000 ℃.
2. Conductive, thermal conductivity: graphite conductivity than the general non-metallic ore 100 times times higher. Thermal conductivity of steel, iron, lead and other metal materials. The thermal conductivity decreases with increasing temperature, and even at very high temperatures, the graphite becomes an adiabatic body. Graphite can conduct electricity because each carbon atom in the graphite forms only 3 covalent bonds with other carbon atoms, and each carbon atom retains 1 free electrons to transmit the charge.
3. Lubrication: Graphite Lubrication performance depends on the size of the graphite scale, the larger the scale, the smaller the friction coefficient, the better the lubrication performance.
4. Chemical Stability: Graphite at room temperature has good chemical stability, acid, alkali and corrosion resistance to organic solvents.
5. Plasticity: Graphite Toughness is good, can grind into thin flakes.
6. Resistance to thermal shock: Graphite can withstand the drastic change of temperature when it is used at ambient temperature, but the volume of the graphite will not change when it is changed.