Graphite is formed at high temperatures, is the most widespread graphite metamorphic deposit，By rich in organic matter or carbonaceous sink Indicates the regional metamorphism Graphite and graphite products in industry application is very wide, used for smelting.　The high temperature of crucible, mechanical industrial lubricants, making the electrodes and pencil lead

　　Graphite and graphite products are widely used in High-grade refractory material and coating of metallurgy industry, military industry, fire engineering materials stabilizer, light industry of pencil lead,The carbon brush of electrical industry, battery industry electrode catalyst, chemical fertilizer industry, etc.Flake graphite after deep processing,But also produce graphite,Graphite sealing material and composite material,，Graphite products,Graphite antifriction additives etc New technology of graphite products, graphite or graphite products become important nonmetallic mineral raw material of each industrial sector.most of world graphite or graphite products production consumption are concentrated in Japan,The United States,Germany and the UK, etc，Industry developed countries,Graphite has good corrosion resistance.

The property of graphite felt used in redox flow battery has a significance to the widely use of redox flow battery.and the Pan base material is the first choice to make the graphite/carbon felt because of the competitive price and good conductivity, chemical stability etc.

　　The electrode material is core component of the redox flow battery,the stability of the electrode material can decide the service time of the battery.now the PAN graphite/carbon felt is widely used as a commercial.

　　The PAN graphite/carbon felt still has a disadvantage,the chemical activity and hydrophilia is not enough,so it need a chemical modification before used in the battery.

　　The main way to modify the graphite/carbon felt as below:

　　1、Oxidation style

　　And it devides into air oxidation style,liquid oxidation style and the electrochemical oxidation.

　　The main purpose is to increase the number of oxygen containing functional groups,such as

　　—COH、—C=O、—COOH and —COOR etc.it can help increase the hydrophilia of the redox flow battery to enlarge the energy efficiency.

　　Currently used for commercial production way is air oxidation style,and it used for Vanadium redox flow battery and Fe/ Cr redox flow battery.The reaction conditions of liquid oxidation style is more calm,and the number of oxygen containing functional groups is more than the air oxidation style,but it need strongly acidic oxidant to modify the graphite/carbon felt,it has a badly corrosion to the equipments,so it’s not suitable for industrial production.

　　2、Other ways

　　Besides of the oxidation style,it also can use Oxygen plasma, γ ray method, hydrothermal method Surface deposition etc.

　　Redox flow battery is a novel kind of secondary batteries to achieve large-scale renewable energy application,and the research and the development on the graphite/carbon felt modification has an important significance.

　　Summary of graphite materials ore resource，Graphite is one of the carbon crystal mineral, lubricity, chemical stability, high temperature resistant, the thermal conductivity of the conductive, special and plasticity, coating and other excellent properties, its application field is very wide.The graphite in the metallurgical industry is mainly used as refractory materials;Used for mould in the casting industry and antirust coating;In the electrical industry for the production of carbon electrode, electrode carbon rods, batteries, made of graphite can be used as a television tube coating, made of carbon products can be used for generators, motors, communications equipment and so on many aspects;In the mechanical industry used as aircraft, ships, trains, and other high-speed operation of the machinery lubricants;In the chemical industry used in the manufacture of various corrosion vessels and equipment;Used in the nuclear industry in the atomic reactor neutron moderator and protective material, etc.;In the aerospace industry to do the rockets the engine tail nozzle throat lining, rocket, missile of insulation, heat resistant materials and satellite radio connection signal and the conductive structure material.In addition, graphite or light polishing agent and anti-rust agent, glass and paper in pencil, ink, black paint, printing ink and the raw material of synthetic diamond.With the development of modern science and technology and industry, the application field of graphite continues to widen, has become an important raw material in the field of high-tech new compound material, plays an important role in the national economy.

       The graphite products are divided into two major categories of flake graphite and microcrystalline ink: flake graphite refers to the natural crystal graphite, the shape of covered, by crystal, flaky graphite ore processed, ore dressing, sometimes by purification products;Microcrystalline graphite has called earthy graphite or amorphous graphite, refers to the tiny natural graphite crystals composed of dense aggregate, by implicit crystal, earthy graphite ore processed, some after the separation, purification products.

　　Flake graphite according to fixed carbon content is divided into high purity graphite, graphite in high carbon graphite, carbon and low carbon graphite four types, according to the product particle size, fixed carbon content is divided into 212 kinds of brands, various grades of graphite products technical requirements are shown in table 4.13.2.High purity graphite (fixed carbon content is greater than or equal to 99.9%) is mainly used in flexible graphite sealing material, instead of platinum crucible is used for chemical reagent melting and lubricant base, etc.;High carbon graphite fixed carbon content (94.0% ~ 99.9%) is mainly used for refractory material, lubricant basic material, brush materials, electrical carbon products, battery materials, pencil, filling material and coating raw materials, etc.;Carbon graphite fixed carbon content (80% ~ 94%) is mainly used in the crucible, refractory materials, casting materials, casting paint, pencil raw materials, battery materials and dye, etc.Low carbon graphite (fixed carbon content is greater than or equal to 50.0% ~ 80.0%) is mainly used in casting coating.

        Microcrystalline graphite divided into iron requirement and no iron requirement 2 class, according to the product of fixed carbon content, the maximum size is divided into 60 brands, various grades of graphite products the appearance requirements shall not be visible to the naked eye in the wood, iron, stone grain and other sundry, product is not contaminated with other impurities, its technical requirements are shown in table 4.13.3.Microcrystalline acid soluble iron content in the ink is not greater than 1%, mainly used in pencil, batteries, electrode, graphite emulsion, graphite bearing of ingredients and raw material of battery carbon rod;No iron requirements of microcrystalline ink is mainly used for casting materials, refractory materials, dyes, electrode paste material, etc.

           Using graphite as electronic conductor material of the electrode.Graphite chemical properties is stable, low overpotential of chlorine, good mechanical strength, easy processing, price moderate.Is widely used in industry, such as used in dry cells positive electrode collector body (graphite rod), industrial electrolytic cell anode, etc.Of chlor-alkali industry in the early, chloride with graphite electrode material, but the drop of slag after chlorine corrosion such as chip jams diaphragm is easy to cause short circuit, shorten the life of electrolyzer, is gradually replaced by titanium form stable anode.In the lab is also commonly used as a price lower inert electrodes.

　　The graphite used discharge loss smaller;Because the spark oil also contains C atoms, in electro discharge machining, the C atoms are deliquescence in low temperature lead to spark oil, instead of care for membrane, the outline of the graphite electrode made up for the loss of graphite electrode.

　　Other, graphite or light property of glass and paper polishing agent and anti-rust agent, is to build a pencil, ink, black paint, printing ink and natural diamond, diamond no shortage of raw materials.It is a very good energy conservation and environmental protection material, the United States has used it as a car battery.As the best contemporary science technology and industry, expand the application range of the graphite in endless, has become a high-tech new composite material demand to the scope of the raw material, in oh economy has the need to see.the lighter weight: the density of graphite only 1/5 of copper, large electrode in EDM, effective low machine tools (EDM) tired of falling;The use of more right in in the large mould.

　　Material is less simple deformation: in thin steel electrode processing on the upper hand clearly;The softening point of copper in 1000 degrees, simple deformation because of the heat;The sublimation of graphite temperature is 3650 degrees;1/30 of the thermal expansion coefficient of the copper. wear-resistant lubricating material: graphite as smooth agent in mechanical property.Smooth oil often means less than on the premise of high speed, low temperature, low pressure, and graphite can wear resistant materials in 200 ~ 2000 ℃ temperature under high sliding velocity, not oil.Many walks of oxidation medium equipment, throughout the adoption of graphite material made from the piston cup, seal and bearing, no need to join when they run smooth oil.Graphite is a lot of metal processing (wiredrawing, laguan) good lubricant.

　　New application of graphiteas a conductive material: on the electrical property is used as electrode, carbon brush, rods, tubes, the anode, to the mercury is graphite gaskets, mobile phone parts, television tube coating, etc. the processing speed faster: usually environment, graphite the machine rate of 2 ~ 5 times faster than copper.The discharge processing speed is faster than copper 2 ~ 3 times;

　　So, it is a kind of ambition sealing material.Popularity is used to heat the oil chemical industry, atomic energy and other belongings.The international market demand is increasing year by year.as refractory material: graphite and its products have the essence of the low temperature resistance, high strength, the first is used to produce graphite crucible in the metallurgical property, the graphite is commonly used in steelmaking for ingot protectant, metallurgical furnace lining. Graphite pencil lead, pigment, polishing agent.Graphite through special processing, can make all kinds of uncommon material used for the fortune some.

　　For atomic energy wealth and possessions of defense: graphite is good neutron moderator for atomic reaction in the heap, a uranium graphite feedback heap is used more of an atomic pile response.As power with slow data in a nuclear reactor should have high melting point, the stability, resistance to oxidation of defiance, graphite can completely meet the above requirement.As feedback atomic pile with graphite requires high purity, impurity content should not across dozens of PPM.Rated a boron content should be less than 0.5 parts per million.Also used in the defense of property of graphite produce solid rocket nozzle, missile nose cones, space travel is equipped with the machine, heat insulation material and the ray material.9, electrode, graphite can somehow replace copper as electrode?don't have a burr;Copper electrode in the processing is completed, still need to manually trim to remove burrs, and no burr after graphite processing, save a little ready cash, at the same time are easier to implement positive change production;graphite has good chemical stability.Graphite by uncommon processing, has the oxidation resistance, good thermal conductivity, seeping into the elementary characteristics of seepage rate, small amount used to produce heat interchanger, reaction tank, condensation, ignition, attract towers, cooler, heater, filter, pump facilities.Widely applied to heat the oil chemical industry, hydrometallurgy, acid and alkali production, synthetic fiber, paper and other part of fortune can be so much the amount of metal materials.

　　　Czochralski silicon single crystal thermal field in the pulling of monocrystalline silicon and polysilicon ingot furnace with heater in thermal field, isostatic pressing graphite parts have crucible crucible, heater, electrode, insulation shield, seed crystal holder, rotating with the base of the crucible, all kinds of round board, thermal baffle, about 30 kinds. Among them, 80% of the isostatic pressing graphite used in the manufacture of crucible and heater, etc. In recent years, the diameter of the requirements of single crystal silicon rod is more and more big, 300 mm wafer production has increasingly become the mainstream. Accordingly, the single crystal furnace heating zone, most of the 800 mm diameter, the graphite crucible furnace in order to protect the place of the quartz crucible, up to 860 mm in diameter, heater is about 960-1000 mm in diameter, the diameter of the other components in some maximum up to 1500 mm. Since 2003, the people of the earth's living environment protection consciousness gradually strengthened, people more and more favour not the natural energy of carbon dioxide. Under this trend, the solar cell production increase. In the process of solar cells, polycrystalline silicon chip manufacturing, must first to polysilicon pieces fused into polycrystalline silicon ingot. The ingot furnace isostatic pressing graphite heater needs to be used to make. 2.2 nuclear power industry in recent years, the global climate warming. People think that carbon dioxide produced by the use of fossil fuels is the leading cause of the problem.

　　In recent years, although the economic growth of developing countries have made remarkable achievements, but the problem of insufficient power deeply disturbed in these countries. In such cases, people's eyes turned to the energy flow density is much higher than solar and wind power, and do not emit carbon dioxide and sulfur oxide nuclear power generation. At present, the world has been put into use nuclear reactors are mostly is given priority to with light water reactor. This DuiXing working principle is to use nuclear cracking when the heat energy to the cold water gasification is 300 ℃ water vapor, drive a turbine to generate electricity. However, due to water reactor temperature is low, the power generation efficiency of light water reactor is not too high. Compared with high temperature gas cooled reactor has no such problem. It is coolant with inert gas (helium), not only the core outlet temperature can reach 1000 ℃, power generation efficiency is high, also suitable for manufacturing hydrogen. Can be said to be the power supply and environment protection. Graphite for this kind of high temperature gas cooled reactor core material, because of graphite not only high temperature resistant, and less to absorb neutrons, good heat transfer. Almost inexhaustible fusion fuel and material resources, the release of the reaction energy is very huge. To make a fusion of for a long time we have to maintain plasma at a certain temperature. Graphite is a fusion plasma maintain an indispensable material.

　　In order to shorten the production process, reduce the cost, improve the quality, reduce the labor intensity and pollution to the environment, the metal material production gradually to the continuous casting direction in 20 years.

　　So far, the basic realization of the copper, aluminum production, high purity graphite, steel production has reached more than 80% (but most of the mold is not using graphite).

　　Isostatic graphite is mainly used for large copper production line. Since 1985, our country from Austria, France, Switzerland, Japan and other countries has introduced more than 30 production lines, and to design our own manufacturing production line has reached more than 100, using graphite crystallizer.

Graphite for electrical discharge machining

　　Electric spark machining is a revolution in the die and mould industry. It not only simplifies the traditional process, but also makes it possible to make a shaped mould. Because of the isotropic, the graphite electrode is the best material for the manufacture of electric spark graphite electrode.

Graphite material for the production of quartz crystal silicon

　　The quartz crucible is a container of a single crystal silicon, and the graphite crucible is used as a molding material in the manufacture of quartz crucible.

　　In addition to the main purposes, such as static pressure graphite is widely used in the field of hard alloy (vacuum oven heater, sintered plate, etc.), mining (bit mould manufacturing), chemical (for heat exchanger and anticorrosive parts), metallurgy Qian Guo, machinery, mechanical seal), space (nozzle), graphite reactor (deceleration material and reflective material) etc..

          Isostatic pressing graphite is developed in the 1960 s a new type of graphite materials, has a series of excellent performance. Isostatic pressing graphite heat resistance good, for example, in an inert atmosphere, with its mechanical strength not only the rise of temperature, increase, in the 2500 ℃ maximum when left to the right; Compared with ordinary graphite, fine structure and uniformity; Low thermal expansion coefficient, excellent thermal shock resistance; Isotropic; Thermal conductivity and chemical corrosion resistance is strong, conductive good performance; Excellent machining performance. It is precisely because has a series of excellent performance, such as static pressure graphite in metallurgical, chemical, electrical, aerospace and atomic energy industry and other fields is widely used, and, with the development of science and technology, application field continues to expand.

　　1 the isostatic pressing graphite production process

　　Very apparently, production technology of isostatic pressing graphite and graphite electrodes. Isostatic pressing graphite need the structure of isotropic materials, you need to raw material grinding into a fine powder, need to apply cold isostatic pressing molding technology, roasting cycle is very long, in order to achieve the target density, need many times

　　Dip - roasting cycle, cycle of graphitization is much longer than ordinary graphite.

　　1.1 raw material to produce isostatic pressing graphite materials including aggregate and

　　Adhesives. Aggregate is usually with petroleum coke and pitch coke and pitch coke also have land, such as the POCO AXF series isostatic pressing graphite, pitch coke is land Gilsonitecoke production. In order to according to the different USES to adjust the product performance, also useful carbon black, artificial graphite additives. In general petroleum coke and pitch coke calcined under 1200 ~ 1400 ℃, to use to remove moisture and volatile matter. But in order to improve the mechanical properties and structure of the product density, also has a direct made of raw material to produce the isostatic pressing graphite raw coke. Raw coke is characterized by containing volatile, has since the sintering, and the binder coke synchronous expansion and contraction. Adhesives usually use coal tar, according to the different equipment condition and technical requirements of various enterprises, using the coal asphalt softening point from 50 ℃ to 250 ℃. Isostatic pressing performance of graphite under the influence of raw material is great, the selection of the raw material is needed to produce a key link in the process of the final product. Prior to feeding uniformity of material characteristics and strict inspection.

　　1.2 milling isostatic pressing graphite aggregate size usually require up to 20 microns below. At present, the most elaborate isostatic pressing graphite, maximum particle diameter of 1 mu m, it is very fine. The aggregate coke grinding into fine powder, so need to use superfine mill. Grinding of average particle size of 10 ~ 20 microns powder need to use the vertical roller mill, the grinding powder of average particle size less than 10 microns will need to use the airflow mill.

　　1.3 kneading will manufacture fine powder and coal asphalt binder in proportion into the mix and pinch machine heating type kneading, make coke powder particle surface evenly attached to a layer of asphalt. After kneading, paste, to make it cool. Compared with graphite electrode production, the production of the isostatic pressing graphite kneading asphalt quantity is more, when the temperature is higher, some time longer.

　　1.4 secondary flour paste after crushing, grinding, and the screen is divided into several dozens to hundreds of micron particle size of particles after mixing, used as a molding material, called pressed powder. Secondary grinding equipment is usually use vertical roller mill and ball mill.

　　1.5 molding is different from the ordinary and extrusion molding, such as static pressure is graphite by cold isostatic pressing technology molding (figure 2). Powdered materials will be filled to the rubber mold, high frequency electromagnetic vibration, pressure powder is close-grained, after sealing process of pumping air into vacuum state, discharge the air between powder particles, in the containing water or oil liquid medium, such as high pressure vessel, pressure to 100 ~ 200 mpa, compressed into cylindrical or rectangle products. According to PASCAL's principle, through the liquid medium such as water pressure to the rubber mold, pressure is equal in all directions. In this way, the pressure in the mold powder particles is not according to fill in the direction of orientation, but is compressed by the irregular arrangement, therefore, in spite of graphite on the crystallographic features is anisotropic, but overall, isostatic pressing graphite Is isotropic. After molding products in addition to the cylindrical, rectangular, including the shape of cylinder, crucible, etc. Isostatic pressing molding machine is mainly used in powder metallurgy industry. Due to the aerospace, nuclear industry, hard alloy, high voltage electromagnetic and other high-end industry demand, isostatic pressing technology is developing very fast, already have manufacturing work cylinder inner diameter 3000 mm, 5000 mm, maximum working pressure 600 MPa cold isostatic pressing machine. At present, the isostatic pressing graphite carbon industry used in the production of cold isostatic pressing machine specification is the largest Φ 2150 mm * 4700 mm, and maximum working pressure of 180 mpa.

　　1.6 roasting in the roasting process, complex chemical reaction taking place between aggregate and caking agent, adhesives, release a large number of volatile, at the same time polycondensation reaction. At low temperature preheating stage, raw products, because of the heat in the subsequent heating process, the volume contraction due to condensation reaction. The greater the volume of raw products, the release of volatile, the more difficult, and raw products surface and internal easy to produce temperature difference, thermal expansion, the phenomenon such as uneven contraction, which may lead to crack of raw products. Isostatic pressing graphite because of its fine structure, especially slow roasting process requires you to be, and have to be very uniform furnace temperature, especially in the asphalt volatile discharge temperature stage, sharply to caution, heating process, heating speed cannot be more than 1 ℃ / h, furnace temperature difference requires less than 20 ℃, the process need about 1 ~ 2 months.

　　1.7 dipping in the process of roasting, volatile bituminous coal is expelled. Gas discharge and volume shrinkage when leaving tiny pores in the products, and are almost open porosity. In order to improve the products of the volume density, mechanical strength, electrical conductivity, thermal conductivity, resistance to chemical reaction, can be treated with pressurized impregnation method, namely through opening stomatal coal tar dipping into the products. Products should be preheated, then in the macerate tank vacuum degassing, again good molten coal pitch to join the impregnating tank, pressure make impregnant pitch into the products inside. Usually, the isostatic pressing graphite to after many times of dipping - roasting cycle ring.

　　1.8 graphitization The products are heated to about 3000 ℃ after roasting, carbon atoms in crystal lattice ordered arrangement, completed by carbon to graphite, called graphitization. Graphitization method has acheson method, internal combination method, high frequency induction method, etc. Usually acheson method, products from furnace charging to emerge, needs to yellow four letters about isostatic pressing graphite production technology, main USES and the analysis of the domestic market 5, 34, 1-1.5 months. Each furnace can handle several tons to dozens of tons of calcined product. After graphitization, products of the volume density, conductivity, thermal conductivity and corrosion resistance have been improved greatly, machining performance is also improved. However, graphitization reduces flexural strength of products.

　　1.9 check after graphitization, also need to products of density, hardness, strength, resistivity, ash content, such as index to check, to determine whether meet the requirements of indicators. 1.10 purification isostatic pressing graphite when used in semiconductor, monocrystalline silicon, atomic energy, and other fields, has a high requirement on the purity and must be used a chemical method to remove impurities, can be used in these areas. To remove impurities in the graphite, usually put graphitization products in halogen gas heated to about 2000 ℃, the impurity was halide halide of low boiling point and volatile. Almost all of the products graphitization of the impurity elements can use chlorine gas halide. But exceptions boron element, it can only get rid of fluoride. Used for purification of halogen gas have chlorine, fluorine, or is that under the condition of high temperature decomposition of these halogenated hydrocarbon gas, for example, carbon tetrachloride (CCl4), dichlorodifluoromethane (CCl2F2). The purification method can make full use of the graphite in the heat does not react with halogen, and the unique properties of porous graphite.

       Graphite crucible can be widely applicable to smelting of gold and silver, copper, iron, aluminum, zinc, tin, and adapt to the coke, oil, natural gas, electric and other smelting various heating methods. Advanced crucible molding technology of static crucible forming method, this technique make the crucible: volume density, high temperature resistant, heat, acid alkali corrosion resistance, high temperature strength, oxidation resistance of high, save fuel at the same time and reduce the labor intensity of the workers. Products have been widely used in power, metallurgy, oil, fire, chemical, two network transformation and other basic industries and modern engineering facilities.

　　The below is the characteristics of graphite crucible:

　　1. The chemical graphite crucible is used for the natural graphite crucible, which has good thermal conductivity and saves fuel.;

　　2. The operation of the aluminum crucible is convenient, has a good mobility, the environment is very small;

　　3. Aluminum graphite crucible should use natural graphite, good retention of the characteristics of graphite, high temperature, alumina graphite crucible with good heat resistance, can be high temperature 1800 degrees;

　　4. Aluminum graphite crucible surface contains special coating, good corrosion resistance, oxidation resistance;

　　5. The aluminum material of the aluminum graphite crucible pollution is rarely, almost zero.

　　The graphite crucible is widely used in metallurgy, foundry, mechanical, chemical and other industrial departments. It is widely used in smelting and smelting of alloy tool steel and smelting of nonferrous metals and alloys. It has good technical and economic effect.. How are these features reflected?

　　1. The density of the graphite crucible makes the crucible have the best heat conduction, and its heat conduction effect is better than other imported crucible.

　　2. The graphite crucible has a special glaze layer and compact molding material, which greatly improves the corrosion resistance and prolongs its service life.

　　3. Graphite crucible graphite ingredients all of the natural graphite, thermal conductivity is very good. The graphite crucible can not be heated immediately after it is placed on the cold metal desktop, to avoid it caused by a sharp cooling and rupture. A variety of small number of the most suitable for alloy melting crucible. To change the type of the alloy, only the exchange of graphite crucible can be. Other fusion methods like reverberatory furnace and crucible induction furnace melting, suitable for in a large number of single alloy melting, if transform melting alloy type, if not replacing lining refractories, metal pollution.