Manufaturing technique of refractory products is similar with that of common graphtie prodcut. The basic process are as follows:

　　Selecting Raw Material → Heating Raw Material → Smashing → Compounding → Molding Biscuit → Drying →Presintering Biscuit →Rough Machining →Sintering → Final Machining → Inspecting→ Finished Product.

　　1. Selecting Raw Material

　　When peolple are selecting raw material, they should take application into consideration. Most raw material is chemical material, only a few raw material is raw mineral materials. Usually, we can get raw material from market. And some special raw material should be compound by people themselves.

　　In general，the purity of raw material is very high. For example, when people produce magnesia carbon brick, content of magnesium oxide should exceed 95% and content of flake graphite should exceed 92%. From a material point then, the purity of raw material should be as high as possible. However, nothing is evidable. High purity means high cost.Like producing magnesia carbon brick, If people ensure the impurity of iron trioxide below 0.35%, the final product must will be qualified.

　　2. Heating Raw Material

　　The material which is applied to manufacturing graphite refractory products, especially oxidised raw material, need to be heated previously. Heating process can be divided into two aspects: the one aspect s calcine, which means burning raw material under a lower temperature that below final maching temperature, which aims at removing volatile impurities and inclusions, reducing contraction of briquettes, and promoting the transformation of allomorphic crystal form; the other aspect is electric smelting, the procedure of which is melting raw material with electric-arc furnace, smashing raw material after cooling, which can improve control on Dimension

　　3. Smashing

　　Smashing is a really important procedure in the course of producing refractory products, whose objective is to change granularity of raw material. As for benefit of smashing procedure， it can sactter raw material so evenly that biscuit can be molded more easyly. What ‘s more, it can make solid-phase reaction ,which avail sintering under a high temperature circumstance and decreace firing temperature, become more throughly. Furthermore, it can expose more impurity, which increase the purity of raw material.

　　(To be continued)

　　Carbon Fiber Composite is a new kind of structual material which developed obviously in recent ten years. Carbon fiber can be composited with resin, plastic, glass, ceramic, metal and other material, after which the material become high in strength, light in weight and good in rigidity.

　　All in all development prospect of carbon fiber composite material is really wide.

　　Carbon fiber composite material can reduce the weight of aircraft, missiles, spacecraft in a large extent, which is a very nice way to improve payload of those craft. For example, some foreign aircraft and missiles reduce 20% to 30% weight by replace its material by carbon fiber composite. When intercontinental missiles and satellites are flying at a high speed, high temperature of thousand degree was generated by the frictioncraft between skin of craft and air. In order to ensure those craft run in good condition, special protective layer was invented. In fact most of those protective layer was machined by carbon fiber composite material.

　　Those protective layer made by carbon fiber composite have been used widely. At present, carbon fiber material have been used in following fields: fan blade of aircraft engine, floor of aircraft cabin and floor beam, landing gear of aircratf, brake pads, and etc. By the way, carbon fiber composite also can be applied in human body.

　　Activated carbon fiber felt is a kind of high efficient adsorption material which is made of man-made fiber by low temperature carbonization, high temperature carbonization and activation. The product has abundant micropores and high specific surface area, low acid, alkali and ash content, good conductivity and chemical stability; the product has not only excellent adsorption performance, but also has good ability of reduction, adsorption and desorption speed, it can be used repeatedly. This product is mainly used for organic solvent recovery, air purification, sewage treatment, medical care, protective clothing, electronic and energy field, corrosion resistance and high temperature resistance environment.

　　The material can be used for making air filter, activated carbon fiber felt can adsorb the O3 ,SO2 and NO2 in the air and other harmful gases, such as odor, toxic gas, and smoke, etc., and it can be used for cleaning indoor air, kitchen utensils and other polluted indoor air.

　　The features of the activated carbon fiber are as follows:1). 800-1600m2 specific surface area, with abundant neatly arranged adsorption micropore (micropore volume accounted for about 80% of the total pore volume) pore diameter is 10-40A. 2). It contain abundant organic functional groups and has good redox properties and excellent adsorption function of organic substances and inorganic impurities in both gas phase and liquid phase. It has good performance of desorption and regeneration, and can be reused. 3). High strength, low consumption, good filling performance and adaptability, winding equipment.it will not produce loose and excessive packing phenomenon under the vibration.4).It has the property such as acid and alkali resistance, corrosion resistance, high and low temperature resistance and good conductivity.

　　We also can produce the fiber-type activated carbon filtration net or cell foam activated carbon filtration net products.the high quality activated carbon powder is adhered on the fiber filter cotton substrate by the high molecular material. The product not only has the function of filtration, but also it can remove the harmful substances such as benzene,formaldehyde and others in the air effectively,and the absorption rate of the benzene is about 95%. It’s mainly used in air conditioning, air cleaners, water purification and gas adsorption, etc..

　　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%.

　　Almost all impermeable graphite that be applied in chemical industry are manufactured via impregnation . Impregnant is not only applied to filling hole but also to improving mechanical strength of impregnated graphite. But while different impregnat is used, different mechanical strength appear, such as chemical stability, thermal ability, hardness, etc. So when you are choosing impregnant, it should conform to following characteristics:

　　Good chemical stability

　　Good mechanical ability

　　Steady Volume which can suffer impregnation

　　Low water content

　　Low viscosity

　　Peopley usually choose phenolic resin, modified phenolic resin, furfural acetone resin, furfuryl alcohol resin and coal pitch. However, sometimes, people choose organic silicon resin, sodium silicate, molten sulfur, paraffin as impregnant.

　　Impregnated impermeable graphite is simmilar with other graphite material, which have better chemical ability than other non-metallic corrosion resistant materials.

　　There are several tips should be noticed：

　　① Graphite pieces should not contain dust, oil, moisture.

　　② In order to Impregnate thoroughly, and in case of graphite expending, Vacuum degree should be as high as possible.

　　③ The quality of impregnant needs special care. If shrinkage process of resin is incomplete or dehydration is incomplete, the quality of impregnant will change.

　　④ Residual resin on the surface of graphite should be wiped.

　　⑤ Vacuum degree, pressure, time and temperature can decide whether the qualit of first impregnation is good enough.

　　The Graphite crucible has good thermal conductivity and high temperature resistance. It has the resistance property to strain for quick heating and cooling and its thermal expansion coefficient is small in the process of high temperature. It has good corrosion resistance to acid and alkaline solution and good chemical stability. the graphite crucible is widely used in the melting of alloy tool steel and non-ferrous metal and its alloy smelting, and has a good technical and economic effects in metallurgy, casting, machinery, chemical and other industrial sectors.

　　At present, there are two kinds of production processes of graphite crucible in China: plastic forming process and cold isostatic pressing forming process. the plastic forming process which as the clay the adhesive has a long production cycle, high labor intensity, low efficiency, coal burning, severe pollution, many Chinese manufacturers use this process because of less investment now, and the isostatic pressing technology equipment using clean energy natural gas sintering, it solves the problem of pollution fundamentally and reduce the the production process of nearly 10, short cycle, high efficiency.

　　Our company can supply the following types of crucible at present:

　　The main components of graphite crucible are natural flake graphite and adhesive, so it has the advantages such as fast heat conduction, high temperature resistance, good thermal stability and no reaction with the melt, it’s the non-ferrous metal casting container. it is ideal for the melting of aluminum, copper and other metals.

　　Quartz crucible has the advantages of high purity ,high temperature resistance, with big size ,good thermal insulation, economization on energy ,quality stability etc.

　　Fused quartz crucibles are used in the manufacture of silicon metal for semiconductor wafer applications and polysilicon.

　　Silicon carbide crucible, we make it from putting the silicon carbide particles which in different content inside the raw material of the graphite crucible, such as the content is 50%, there are 24%, there are other different content, of course, it can also be customized according to the different requirements of customers.

　　Porcelain/Ceramics/Corundum crucibles are used in laboratory testing.

　　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.

　　Also known as quartz ceramic fused silica ceramics, quartz glass, quartz glass ceramic sintered products, fused silica sintered products (fused silica or fused silica ceramic) is the use of fused quartz or quartz glass as raw material, crushing, molding, sintering and a series of ceramic production process for preparation of products. Quartz ceramic was first developed in 1963 by the United States, and the first to achieve industrial production. In 1972, China Refractory Material Research Institute of China began to develop the new material, which was put into production in refractory material factory. The quartz ceramic not only has many good properties, such as quartz glass thermal expansion coefficient, good thermal shock resistance, good electrical properties, good performance, nuclear chemical resistant characteristics of a good, but also has some excellent properties, such as quartz glass do not have low thermal conductivity; even the crystallization of quartz ceramics it can still be used, and the quartz glass devitrification occurs when using the discarded damage; drying and firing shrinkage, easy molding complex and big products. Therefore, it has a good application prospect in glass, metallurgy, electric power and national defense industry. The application of quartz ceramics in China is mainly concentrated in the glass and steel industry

　　Along with the development of green energy has been paid more attention and developed as a green energy, solar energy popular around the world, has been widely developed and utilized, which makes for the polycrystalline silicon solar energy conversion industry has been developing rapidly. Quartz ceramic crucible for melting polysilicon is square, large size (length can be more than 1000mm), thin wall (10 ~ 20mm), making more difficult. Requirements of high purity, no pollution to polysilicon, the use of temperature can reach 1450 degrees celsius.

　　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.

　　Flexible graphite, which is really flexible and resilient, is called expanded graphite and vermicular graphite, who is pure graphite material not containing any binder or adhesive substances, and which owns features of corrosion resistance, high temperature resistance, low temperature resistance, radiation resistance and anisotropic resistance, and which also can be applied in lubricating. Flexible graphite particles can be produced into mechanical sealing product, such as, graphite sheet foil, graphite packing ring, stainless steel graphite spiral-wound gasket. By the way, flexible graphite product can produced in different shape to meet different shape demands.

　　As for property, in crystral structure aspect, there is no difference existing between flexible graphite and ordinary graphite. However, because of different produce flow, flexible graphite has its unique edge, such as, advanced thermal stability(high temperature resistant, low temperature, high heat conductivity and low thermal expansion rate), chemical corrosion resistance, radiation resistance, self-lubrication, excellent mechanical ability.

　　As for application, flexible graphite product has been appllied in petroleum, chemical, fertilizer, chemical, pesticide, thermal power, metallurgy, aviation, machinery, nuclear industry and so on, which definately is an outstanding sealing material for pumps, valves, piping and other equipment. In 1980s, an American announced that his experiment shows the perfmance of graphite equipment made by flexible graphite is far better than that made by impregnated graphite.

　　After my introduction, you must have your own comprehension on flexible graphite product. Our company—BeiJing Great Wall Co. ltd—are professional suppiler for graphite product with 13 years’s experience. If you are in the market of graphite product, welcome to our website:www.bjgreatwall.com.