PAN based plate felt as the material, the high temperature of graphite to make carbon felt, can be used as a variety of high temperature vacuum furnace insulation materials, but also can be used as carbon / carbon composite material.

　　Application case:

　　The products involved in the field of aerospace, vacuum metallurgy, photovoltaic solar new energy, new chemical materials, is the kinds of domestic products, research and development capabilities of the strongest specializing in the production of hard composite mat and batch production of high-temperature high purity graphite felt material manufacturers. Main production carbon felt, graphite felt, hard composite mat, ancillary products are mainly molybdenum wire, carbon cloth, carbon rope, etc., products widely used in all kinds of high temperature vacuum furnace equipment (such as: single crystal growth furnace, polycrystalline casting furnace, polycrystalline reduction furnace, vacuum sintering furnace, hot pressing furnace, heat balance of furnace, induction furnace, non oxidizing atmosphere high temperature equipment, high purity silicon hydrogenation furnace, etc.).

　　Features: high temperature resistance, corrosion resistance, small specific heat capacity, good thermal insulation, high purity, low ash, soft and soft properties, and a high degree of shape retention. In the high temperature environment of vacuum or inert gas, the performance of thermal insulation material is very good and stable, which is a good thermal insulation material of silicon and polycrystalline silicon.

　　The carbon/graphite felt have the characteristics of light weight, high tensile, abrasion resistance and excellent eletctrical and are widely used in semiconductor, energy , machinery and other inductrial fields as thermal insulation material.. Since these furnaces work at extremely high temperatures, it is necessary to have insulation material that can withstand such high temperatures. Moreover, for energy conserving purposes, quality heat insulation material is the best choice. We pride ourselves in the ability to offer first class technical backup to our customer base. we produce all of our own carbon and graphite thermal insulation materials under the strictest quality standards.Flat, board and cylindrical shapes of products are available, it’swidley used in high vacuum and furnace f inert gas..

　　The rayon based rigid graphite felt and pan based rigid graphite felt are processed for inert or vacuum furnaces up to 2500 D.C. Graphite foil or paint can be covered on surfaces to reduce dusting,out gassing,or applied as heat reflection.

　　The graphite felt is normally classified into asphaltic based graphite felt, PAN based graphite felt &rayon-based graphite felt. The mainly application is electric conduction in the photovoltaic industry, as the heat retaining material, thermal insulation material for the smelting furnace and vacuum furnace, and in chemical industry it could be the filtration material, it can be used for Vacuum Furnace, High Temperature Sintering Furnace, Solar Silicon Furnace, crystal growth furnace, inert atmosphere furnaces, semiconductor furnace, multicrystalline DSS, Directional Solidification System(DSS) furnaces.

　　Graphite rigid felt is a shaped machined insulating material made of graphite fiber or felt and carbon binding.It is new material based on PAN-Carbon and graphite felt and bonded with special binding agent. With properties of rigid, smooth surface, low specific gravity,good anti-bending and compression strength, it can be used in vacuum furnace for heat insulation,in order to prevent fluffing, the felt can be surface-treated by special coating, graphite paper/cloth liner,etc.

　　The pan based Graphite felt was treated by a special process high temperature graphitization, with light weight,high carbon content,ablation resistance,corrosion resistance,high purity,high temperature without volatile,small coefficient ofthermal conductivity,without any deformation.

　　The graphite felt is normally classified into asphaltic based graphite felt, PAN based graphite felt &rayon-based graphite felt.

　　The mainly application of the graphite felt is electric conduction in the photovoltaic industry, as the heat retaining material, thermal insulation material for the smelting furnace and vacuum furnace, and in chemical industry it could be the filtration material. it is used to vacuum furnace(especially suitable for the single crystal furnace) as insulation heat preservation material,also can be used as infrared heating wire and electrode materials.

　　The graphite felt is formed after above 2000℃ high temperature treatment under inert gas or vacuum. The polypropylene cyano is the major raw material. The polypropylene cyano carbon felt or rayon-based carbon feltis cuttd into the specific dimension, and loaded into the graphite vessel after rolled. The graphite vessel will be setted in the high temperature furnace, protected in vacuum or by high pure inert gas. It's heated up to 2200-2500℃with the heating rate 100-300℃/h, then get the final product after naturally cooled to 100℃ .

　　Our products involved in the field of aerospace, vacuum metallurgy, solar new energy, new chemical materials, we are the manufacturer which is specializing in the production of rigid composite graphite felt and high temperature and high purity graphite felt materials for domestic in China. The main products are carbon felt, graphite felt,rigid composite graphite felt and the auxiliary products such as carbon cloth, carbon rope and so on ,our products are widely used in all kinds of high temperature vacuum furnace equipments such as single crystal growth furnace, polycrystalline casting furnace, polycrystalline furnace, vacuum sintering furnace, hot pressing furnace, heat balance furnace and electric magnetic induction furnace ,non-oxidizing atmosphere high temperature equipment and high purity silicon hydrogenation furnace etc..

　　The graphite felt is normally classified into asphaltic based graphite felt, PAN based graphite felt &rayon-based graphite felt. The mainly application is electric conduction in the photovoltaic industry, as the heat retaining material, thermal insulation material for the smelting furnace and vacuum furnace, and in chemical industry it could be the filtration material.

　　The carbon/ graphite felt is made of oxidized PAN short cut fiber. And after opening, carding,

　　lapping, needling,it is made into a certain density and thickness. Some excellent performances such as high purity, soft texture, No dus and chemical corrosion resistance will be obtained by

　　special carbonization and graphitization process .The carbon/graphite felt can improve the current

　　density of the liquid flow battery, and it has the protective effect on the corrosion resistance of the bipolar plate and is mainly used as the electrode of the liquid flow battery industry.

　　The graphite felt is formed after above 2000℃ high temperature treatment under inert gas or vacuum.The polypropylene cyano is the major raw material. The polypropylene cyano carbon felt or rayon-based carbon feltis cuttd into the specific dimension, and loaded into the graphite vessel after rolled. The graphite vessel will be setted in the high temperature furnace, protected in vacuum or by high pure inert gas. It's heated up to 2200-2500℃ with the heating rate 100-300℃/h, then get the final product after naturally cooled to 100℃.

　　PAN Based Carbon Felt is used in high temperature insulation in resistance or induction heated vacuum furnaces and inert gas furnaces. Made of carbon or graphite fibers, these materials have low thermal conductivity and vapor pressure. it is considerably less expensive and more effective than metallic radiation shields and may be used to replace them, with power savings of up to 75%. The low specific heat and low density permit rapid heating and cooling of furnaces.

　　The electrode material is one of the key materials for vanadium redox flow battery. Due to the large surface area and good stability, the graphite felt is dominant. However, the graphite felt material has poor hydrophilicity, and its electrochemical activity is not good enough. This paper on the graphite felt electrode respectively chromic acid oxidation method, mixed acid electrochemical oxidation method and hydrothermal ammoniation method for processing vanadium redox flow battery to improve its activity, the main conclusions are as follows: after chromic acid oxidation, hydrophilicity and electrochemical activity of the Shi Mozhan electrode increased, the optimum processing time is 5 h. In the 10 to 70mA/cm2, the battery with the graphite felt after the treatment with the chromate has a good charge discharge performance.

　　The efficiency of the battery voltage is about 90.9% and the energy efficiency is up to 79.4% at mA/cm2. FT-IR and SEM show that the carbon fiber processing after the oxygen functional groups increased and the surface gully increased, the former increased the number of active sites on surface of carbon fiber in VO2+/VO2+ electrode reaction, which increases the contact area of vanadium ion and electrode. The hydrophilicity and electrochemical activity of the graphite felt electrode were obviously enhanced after the electrochemical anodization of sulfuric acid and phosphoric acid. The optimum treatment conditions were as follows: the current density was 50 mA/cm2 and the treatment time was 4min. The processing of graphite felt is loaded into the cell, showing good charge and discharge performance in 10 to 50 in mA/cm2, 20 in mA/cm2, the battery voltage efficiency of 88.2%, energy efficiency reached 79.6%. FT-IR and SEM tests showed that the oxygen functional groups on the surface of carbon fiber increased, and the surface roughness increased. The results of XRD show that the crystallite size and the space between the carbon fibers decrease, which indicates that the electrochemical oxidation etching the graphite crystallites in the outer layer, which is the reason for the increase of the surface roughness of the carbon fiber. For the first time put forward 180 degrees in the hydrothermal ammoniation of graphite felt electrode, hydrophilicity and electrochemical activity of treated graphite felt electrode increased, the optimum processing time is 15 H.

　　The processing of graphite felt is loaded into the battery, charge and discharge can be stabilized in 20 to 60 in the range of mA/cm2. In 20mA/cm2, the voltage efficiency can reach 83.7% and the energy efficiency is up to 85.3%. The reason lies in the improvement of electrode active carbon fiber surface increased nitrogen content of functional groups and nitrogen functional groups to enhance the positive charge density of the alkaline carbon fiber and its adjacent carbon atoms, to speed up the transfer speed of vanadium ions and electrons in the electrode / solution interface, improve the vanadium ion diffusion process, reduces the electron transfer resistance.

　　Graphite felt has good stability, the unit cost of large surface area, good permeability of the advantages of electrode materials used in direct methanol fuel cell flow, but because of its poor hydrophilicity, electrochemical activity is not high, which greatly limits its application. Therefore, we try to improve the electrochemical properties of carbon atoms by changing the electronic structure of carbon atoms. Although the nitrogen doped graphite felt has been reported sporadically, the research on the nitrogen doped graphite felt used as the cathode of direct flow methanol fuel cell is still in the blank.

　　With the energy and environmental problems become more and more prominent, the research and development of green, pollution-free new energy has been attached great importance by the enterprises and the government. Fuel cell is a kind of clean energy which can directly convert the chemical energy into electric energy.

　　The graphite felt has the advantages of good stability, large surface area per unit cost and good fluid permeability, but its application is limited because of its poor hydrophilicity and low electrochemical activity. Therefore, it is hoped that the surface treatment can improve its electrochemical performance. Commonly used acid treatment, heat treatment, electrochemical oxidation, rare earth ion modification methods.

　　The electrode material is one of the key factors to restrict the development of the liquid flow battery. It needs to meet the requirements of high conductivity, large surface area, high selectivity to a specific reaction, good electrochemical activity, good chemical stability and so on. The main researches are metal, composite and carbon. The metal electrode has good conductivity, excellent mechanical properties, high electrochemical activity, but the stability in the anode region is poor and expensive, it is not suitable for large-scale applications; composite electrode material is a polymer and conductive carbon mixing, drying and tabletting after prepared, while improving the conductivity, oxidation but the need to overcome the polymer at high temperature; carbon electrode mainly include carbon cloth, graphite, carbon fiber and graphite felt, good stability and low cost, but the graphite, carbon fiber and carbon cloth used as electrode, a few cycles, the electrode surface is damaged, only the graphite felt electrode is the present study is more and more widely used as electrode material.

　　At present, the domestic production of graphite felt is mainly used to make thermal insulation material, and its conductivity and electrochemical activity can not meet the requirements of the use of battery electrode materials, therefore, it needs surface treatment on the for graphite felt .Commonly used surface treatment methods include heat treatment, acid treatment and electrochemical oxidation treatment.

　　The operation of heat treatment in air atmosphere, and the heat treatment after carbon fiber conductive ability has been improved, but there is no deep research on revealing fiber structure changes and conductive ability of the report.

　　The surface morphology and structure of carbon fiber felt changed before and after heat treatment, and the conductivity of the carbon fiber felt was also affected. The mass loss of carbon fiber felt was slow at the beginning, and gradually increased when the temperature exceeded 450 degrees celsius.

　　This is because oxygen started contact with graphite felt when exposed to only the surface of some active substances, the reaction is slow; with the reaction, oxygen gradually exposed to the fiber body, which is also affected by the oxidation erosion, the integrity of the fiber was damaged.

　　In the heat treatment of graphite felt, if the temperature is too low, with active keys C-O and C=O activity were lower than the proportion of the surface area, leading to electrochemical active carbon fiber felt low, unable to meet the requirements of use as electrode materials; but if the heat treatment temperature is too high, it will cause the carbon fiber mat surface etching is serious, excessive oxidation, fiber breakage and breakage, resulting in the electrical conductivity and mechanical properties decreased sharply, seriously affecting their life.

　　There is no surface of carbon fiber graphite felt after heat treatment. The texture is clear, can be observed in some small, parallel to the fiber axis etching grooves and other defects, these defects are mainly due to the formation of polyacrylonitrile carbon fiber precursor phase is used in wet spinning caused by the storm.

　　Graphite felt comprehensive performance is the best of the electrode used in battery.but it still need to do some activation treatment to improve the activity.

　　The commonly used method:heat treatment,acid treatment, electrochemistry treatment etc.

　　The heat treatment of graphite felt is to put it into the heating equipment, like muffle furnace,to make it oxidation around the surface.

　　Some scholars have found that if put the un-modified graphite felt into the H2SO4 solution,the surface of the graphite felt is hydrophobic,and it need about 48h to be complete wetting.under 200℃ heating environment,and after that,the wetting time can be reduce to about 30h,and with the heating temperature increasing,the graphite felt is easier to be wetting.

　　Under the heating temperature at 400℃ in the air environment for 30h,then make the graphite felt used in the vanadium redox flow battery,we could found that,the heating treatment can apparently improve the electrochemistry property of the graphite felt,and can make the energy conversion efficiency of the battery increase from about 70% to 89%.

　　We could also have a comparation between the modified graphite felt and the un-modifified ones,we could found that the absorption rate of un-modified graphite felt is mearly about 3.2g/g,but the modifified ones,under 400 ℃ environment for 2h,can reach about 10g/g absorption rate.

　　The reason that heating treatment can improve the graphite felt activation is mainly the heating treatment can improve the directional arrangement of the graphitization,and make the electric resistance come down apparently.

　　after the experiment and testing,an appropriate condition can make the graphite felt with a minimum electric resistance,make it used in the vanadium battery pack,during the charging and discharging process,the coulomb efficiency can reach more than 90%.

　　Graphite felt is widely used as a composite conductive layer, suitable for the use of vacuum assisted resin transfer molding, infiltration resistance change process and the curing process of the system is small, in the design and forming the surface of the conductive layer, fiber layer can predict the electrical conductivity of composites. The electrical conductivity of the composite material can be changed to a specific circuit, and there is a layer sensitive area and a pressure sensitive area.

　　Due to the excellent mechanical properties and good electrical conductivity, graphite felt is widely used as conductive materials, electromagnetic shielding materials, fuel cell electrode materials and so on.

　　It can improve the connection between the resin and the fiber by using the surface felt with low surface density, and the vacuum assisted resin transfer molding can make the connection between the layers closer, which is beneficial to improve the performance of the products, with the different carbon fiber content, the trend of the current voltage curve is also different.

　　The graphite felt is composed of short carbon fiber and binder, which is an ordered planar structure on the macro. Because of the existence of overlapping and stacking of short cut fibers, and certain radial bending, the carbon fiber felt can be compressed. Can predict the multilayer overlap, compared with single-layer network more dense, under the pressure of (plane structure, not destroy the carbon fiber can prevent fiber breakage or fracture), network structure intensity will increase further.

　　The electrical conductivity of CFV/EP composites formed by VARTM is related to the density of CFV and the limit of resistivity.

　　All vanadium redox flow battery, using vanadium ion solution as positive and negative electrode active material, the cathode is V (IV) /V (V) of V cathode, (II) /V (III) on the electric potential difference, the standard is about 1.25 V. The battery has the advantages of large capacity, long service life, deep discharge and no damage to the battery, and can realize the instantaneous recharging. At present, the development of vanadium battery is hindered by the electrode material, and the electrode material target is PAN base felt.

　　At present, the production of PAN carbon felt is mainly used as thermal insulation material, the conductivity and electrochemical activity can not meet the requirements of the battery. The effect of heat treatment temperature on the graphitization of graphite felt was further studied.

　　In the heat treatment of graphite felt, the optimum temperature of heat treatment is about 550 DEG C, and the Shi Mozhan resistance is the lowest and the exchange current is the maximum. In the process of charging and discharging, the coulomb efficiency can reach more than 90% by using the graphite felt electrode prepared by the optimum temperature.

　　Electrode material is one of the key materials for all vanadium redox flow batteries. Due to the large surface area and good stability, the graphite felt is dominant. However, the graphite felt material has poor hydrophilicity, and its electrochemical activity is not good enough. This paper on the graphite felt electrode respectively chromic acid oxidation method, mixed acid electrochemical oxidation method and hydrothermal ammoniation method for processing vanadium redox flow battery to improve its activity.

　　The reason lies in the improvement of electrode active carbon fiber surface increased nitrogen content of functional groups and nitrogen functional groups to enhance the positive charge density of the alkaline carbon fiber and its adjacent carbon atoms, accelerate the electrode / solution interface of vanadium ion and electron transfer rate, improve the vanadium ion diffusion process, reduces the electron transfer resistance.