The bearing is a sliding parts commonly used in machinery industry, material and metal, nonmetal, composite materials don't. Graphite bearing is the performance requirements of the mechanical equipment, in the metal bearing on the basis of the development and development of carbon bearings, graphite materials as the main substrate. Graphite bearing is different from the metal bearing characteristics, mainly in: self lubrication, high temperature resistance, corrosion resistance, light weight, etc..

　　Bearings are rolling bearings and plain bearings, and graphite bearings are used for sliding bearings. Used in food, beverage, textile, chemical and other industrial sectors of transport, dryers, textile machines, submersible pump motors and other bearings, such as the use of grease lubricant inevitably lead to pollution, and graphite bearing a strong self lubrication, corrosion resistance, can not make use of lubricants for long-term operation.

     China is the world's leading graphite producing areas, it has the most variety of graphite in the world ,and the production quantity accounted for more than 70% of the world's graphite production. There are 3 main types of graphite in China, namely natural flake graphite, amorphous graphite and artificial graphite.

　　Chinese flake graphite is very famous in the world with more reserves and big production and export volume. The flake graphite was characterized as hexagonal crystal structure, which was in layered structure distribution .The production areas of natural flake graphite mainly concentrated in Jixi, Luobei, Mishan and Muling of Heilongjiang Province, Pingdu, Laixi, Nanshu and Beishu of Shandong Province,Xinghe, Wuchuan and Hohhot of Inner Mongolia. The natural flake graphite production output of these 3 provinces accounted for more than 95% of the country.

　　The natural flake graphite from Heilongjiang ,Inner Mongolia and Shandong has a lot of similarity but they also have the characteristics of themselves . The flake graphite from Heilongjiang has thin slice , good toughness and low iron content, especially be suitable for the battery industry. Flake graphite from Shandong is in standard hexagonal structure,it has the bright appearance , big scales and low content of mica quartz, so the grinding float can make the carbon content more than 98%,reduce environmental pollution and the production cost is low. Flake graphite in Inner Mongolia, the quality of raw ore is slightly higher than it’s from Shandong, it has large and thick scales features, but relatively speaking, the mica content is high, it is not suitable for the crucible industry, but have no influence on the refractory industry, especially for the production and machining of expanded graphite.

　　Amorphous graphite is mainly distributed in LuTang, and Xinhua of Hunan Province, Panshi of Jilin Province, annual output is about 200000 tons, mainly be used as refractory materials.

　　The artificial graphite is a synthetic material that’s graphitized after petroleum coke sintering treatment, mainly be used for graphite electrode, its remaining material after machining or the waste motor has been used by steel plant used can be make into graphite powder, then be used as carburant in steel workses or casting factory.

　　Now,there are many excellent and professional manufacturers of graphite & carbon products in China who can produce and supply high quality graphite & carbon products such as graphite material, graphite rod/block/plate, graphite tube, graphite parts,cylinder of lubricant, graphite electrode, graphite crucible, quartz crucible, carbon felt/graphite felt,graphite foil/sheet and carbon/carbon composite.Chinese graphite has been exported to many countries in the world.

　The density of carbon carbon composite material can be adjust between 1.3~2.0g/m3,and it can be widely used for any parts of the nozzle. According to the different ablation environment,the middle and high density carbon carbon composite material can be used for the throat part,the low density C/C composite material can be used for the back expansion part and the middle and low density material can be used for the front expansion part and the head. In addition,the screw,pin which are also made from the carbon carbon composite material can be used in the nozzle,and the function is connection.

　　The carbon carbon composite material nozzle and expansion part was widely used in the SRM since 1990s, multilevel SRM, strategic missile SRM,rocket booster SRM etc.all use the 3D,4D C/C throat.

　　Carbon carbon composite material is made from the reinforced carbon fiber and carbon matrix,the property of the carbon decides that it can not be made of normal inorganic materials and carbon fiber/ epoxy resin,it needs carbon precursor decomposition then form the matrix carbon to make it. The three basic steps of the technology include:carbon fiber precursor,matrix carbon densifying and high temperature treatment(graphitization). And there are two methods of the densifying,one is liquid phase impregnation(thermosetting resin or pitch),and another one is chemical vapor phase method(CVD with C,H element),and the two methods can also be used together. The technical route:selection of carbon fiber, forming,the densifying of the carbon perform,high temperature treatment and the machining.

　　The function of carbon fiber is increasing the toughness and bearing load,it decides the strength and the rigidity, the direction of the perform carbon fiber also has an important influence on the property of the carbon carbon composite,even the porosity and the distribution,and the structure of the matrix carbon can influence the velocity of densitying, all the influence can influence the strength property and ablation performance.

　As the high tempterature and complexity of the throat environment and the polytrope during the ablation process,the carbon carbon composite material throat also show a complex process,and there are many effects of different degrees from the carbon fiber micro complexity,different technology etc.

　　The type and quality of the carbon fiber has a big influence to the strength and ablation properties of the carbon carbon composite material. There are many different carbon fiber,like PAN base carbon fiber,pitch base carbon fiber,and rayon base carbon fiber,and each kind of the carbon fiber can be divided into many series. The carbon carbon composite material is mainly desined according to the purpose and working environment,the main properties include strength, modulus,thermal property etc. Generally speaking,the high modulus carbon fiber is good at the ablation property,and it can provide the high thermal conductivity,high density,high carbon content and low coefficient of expansion. From the microstructure of carbon fiber,there are some micro pores and cracks inside,all this factors can influence the ablation property of the carbon carbon composite material. So it must chose the carbon fiber according to the different using and different working environment.

　　The structure of the perform can also influence the carbon carbon composite material ablation property and thermal shock resistance. It can influence the distribution and uniformity of carbon fiber in the C/C material. The thermal shock resistance and ablation property can be improved by different perform structure,decreasing the coefficient of expansion and increasing the isotropic degree. The fiber orientation and volume content of the C/C composite material have an apparent impact on the ablation property,more fiber content, uniform structure can increase the ablation property.

　　Besides from the factors above,the material density,porosity,the type of matrix carbon, degree of graphitization and the impurities content also have the influence in the carbon carbon composite material properties.

       Carbon brush is a device which conducts current between stationary wires and moving parts,most commonly in a rotating shaft. it's a sliding contact used to transmit electrical current from a static to a rotating part, in a motor or generator, and as regards DC machines, ensure a spark-free commutation. typical applications include electric motors, alternators and electric generators.

　　Carbon brushes are maintained by brush-holders to be in permanent contact with the slip ring assembly or with the commutator.

　　Carbon Brushes are used in general industrial such as DC motors, Electrical trains, Wind-generated power. industrial carbon brushes are used on large commutator machines, in which the current between the rotor and external circuit is periodically reversed. These include AC and DC motors, slipring rotors, traction motors, turbogenerators, windmills, hydro power stations and steel, cement and paper mills. Industrial carbon brushes also can be used to power battery-driven cars, cable cars and trolley buses, and they are often used in construction vehicles such as forklift trucks and cranes. Brushes connect the generator to the rotor through the commutator, which has copper segments, or lands. The brushes bear the brunt of wear and tear between the rotating rotor and the non-moving generator while conducting electricity between them. Industrial brushes are specially designed to withstand extreme temperatures.

　　The home application of carbon brushes as the power tools like washing machines and disk grinders.carbon brushes are a common component in household appliances such as power tools, gardening equipment and office equipment. Vacuum cleaner turbines, hair and hand dryers, and washing and drying machines are also common applications of this type of carbon brush, which is generally much smaller than its industrial or automotive counterparts. Micro-carbon brushes, for example, are precision parts designed for toys, electric razors, and audio and video equipment. In such small dimensions, carbon brushes are often placed inside tiny battery-operated mini-motors designed to transmit power silently and with the least amount of friction to moving parts such as wheels and razors.

　　As to automotive application of carbon brushes, we will think of automobiles and forklifts.cars generally use small and auxiliary carbon brushes for DC motors, starters and alternators. Alternators are devices that convert mechanical energy to electrical energy. They consist of a wire-coiled rotor that produces a magnetic field when a current runs through it. Automotive carbon brushes are used to supply the current to the wire coil in the alternator. Automotive carbon brushes can be found in most passenger vehicles, motorcycles, trucks and oil- and diesel-fueled cars. Even smaller, specially designed carbon brushes are used in steering wheels and contacts for airbags.

　　The performance and application of carbon brushes in the pulp and paper environment. direct current (DC) motors are used extensively throughout the pulp and paper industry. the motors are used in various applications such as fan pumps, press and winder motors. The maintenance requirements of the motors are different for each application. An important maintenance function regularly performed is the inspection of carbon brushes and commutators. Carbon brushes are critical to the operation of the paper machine with DC motors. Worn or failed brushes can make a paper machine inoperable and cost thousands of dollars per hour.

　　The ablation property of the carbon carbon composite material is the key factor of SRM.

　　The nozzle of the rocket or missile is under the situation of high speed air flow,and this kind of the material has the oxidization property,it will make the throat continuously in the ablation environment. The index of judging the material's erosion performance is mainly including: specific heat capacity,thermal conductivity,ablation rate,density etc. The good specific heat capacity can make the material absob much heat during the ablation process,and the low thermal conductivity can only make the high temperature gathered on the surface of the material,and can not transfer into the inside structure. The low density material can make the total weight lighter.

　　The ablation property of the material is related to many factors, first of all ,the different material has the different way to calculate the ablation rate. Secondly,except for the material ,the ablation rate is also related to the gas content and the tempterature of the environment,thirdly,the thermal conductivity of the gas flow also has an influence on the ablation property. In addition, the relationship between different factors is not isolated,they have the mutual influence. Nowadays,the ablation property of carbon cabon composite material is mainly thought as two parts,the thermal chemical ablation and the mechanical denuding.

　　Carbon carbon composite material still need to improve,and the main direction is below:

　　1、Increase the ablation property of the carbon carbon composite material. Some research show that make the C/C composite material impregnated with certain metal can reduce the ablation rate.

　　2、Optimization of process,the purpose of optimization of process is to “reduce the cost,improve the efficiency” .As is known to all,C/C composite material has many good properties,however,the technology is complex,and the production cycle is very long,and the cost of the processing is very high. So it limit the using on the SRM.

　　3、Strengthening mechanism research of the ablation process.

　Carbon carbon composite material is carbon fiber reinforced carbon composites, belong to the research and development in the field of high and new materials nomatter in China or abroad.

　　In 1958,in the American Chance Vought Airlines Laboratory,the carbon carbon composite material was found by chance, during the testing of carbon fiber content in organic matrix composites,due to the mistake of the experimentation,the organic matrix Pyrolysised,and got the matrix carbon,and the new composite material has many good comprehensive performance,and after that,the C/C composite material was widely used for many high-tech fields.

　　Carbon carbon composite material has the good high thermal resistance performance of carbon material, At the same time,it also has the good strength of the composite material,and it’s also easy to machine,because of so many good properties,it’s widely used for aerospace, atomic energy, metallurgy and other fields.

　　Now, the carbon carbon composite material products already have the mass production,with the cost reducing,the application of it will be wider.

　　The good performance of carbon carbon composite material mainly include:low density,good strength property under the high temperature,good friction performance, excellent ablation performance, high thermal conductivity etc.

　　The carbon carbon composite material product also has it’s disadvantage. Such as the strength property of XY direction is not so good, and the associativity of carbon fiber and carbon matrix is not good,the antioxidant capacity is bad,and the cost of C/C composite material is very high,the processing cycle is long, and the design method is very complex. So many disadvantage restricted the application of carbon carbon composite material.

　　The application fields of C/C material mainly include: 1)brake material field,the military aircraft, civil aircraft, high-speed car etc.2)high temperature structure field,the nozzle,throat of rocket engine etc.3) mechanical manufacture field,it can replace the Hi-Q isostatic graphite,make the crucible,heater, insulation liner etc.4) Biomedical field,it can be made for many artificial organ.5)the C/C material can also be used for sporting goods and daily necessities.

      Both of graphite foil and graphite sheets are flexible graphite products. graphite foil is usually in rolls and graphite sheets has the strengthed style.

　　Graphite foil and graphite sheets are made from compressed exfoliated mineral graphite, pure graphite carbon and without fillers and binders. Most of graphite foil and graphite sheets in the market have a carbon content ranging from 95% -98%. Some brand of flexible graphite foil has a high purity of ≥99% carbon content. The higher carbon content,the better chemical resistance, better thermal conductivity and better sealability.

　　Characteristics of graphite foil and graphite sheets: electrical conductive,thermal conductive;

　　heat and fire resistant; compressible, conformable, low creep relaxation;Chemical resistant, compatible with most chemicals;reinforced structure to handle high pressure applications.

　　Graphite foil and graphite sheets are used commonly in high temperature sealing applications.

　　Applications of graphite foil:

　　- Gaskets material in automotive, petroleum and chemical, paper, and nuclear industries.

　　- Excellent linings and protective layer for vessels containing hot or corrosive fluids.

　　- Excellent for sealing high temperature valves, shafts and flanges.

　　- Fuel cell industry for bipolar plates.

　　Flexible graphite foil is made with pure expanded mineral graphite. As gasket material, it is usually fabricated into Graphite Laminate, reinforced graphite sheet and widely used in fluid sealing applications: flange gasket, spiral wound gasket, heat exchanger gasket, etc. It can also be used as solid lubricant in metal stamping and forming applications, or as heat liner in industry furnaces and other heating devices

　　Graphite sheets typical applications :heat and chemical resistant gasket, seal, liner; thermal conductive seal; heat exchanger gasket.

Carbon carbon composite material is made of carbon fiber reinforced and carbon matrix. The carbon fiber is made from PAN,pitch, rayon etc. and after pre oxidation and carbonization process. The carbon content of carbon fiber is above 90%,and it has a high strength, high modulus and high temperature resistance.

　　PAN base carbon fiber has a good property of strength,and it can be widely used for many industrial field,the PAN carbon fiber is 90% of the world's carbon fiber total. Now,the total output of carbon around the world is amost forty thousand tons. And the production yield of Japan Toray ,Tenax and Mitsubishi will reach 75% of all.

　　The carbon fiber can be used in many field,such as bycicle structure,racing boat, automobile race, brassie etc. it also can be used for aerospace and weapon manufacturing etc.because of the low density of carbon fiber, the specific strength is 7~9 times of the steel and it’s 4 times than aluminum, and when it’s under the under anaerobic conditions,it can be resistant to 2000 degrees celsius temperature,the carbon fiber is the indispensable material of the carbon carbon composite material.

　　As one of the high performance fiber,carbon fiber has the inherent characteristics of carbon materials and is also has the machinability of textile fibers. It has an extensive application areas,especially in some special high-tech fields.

　　The quality of the carbon fiber is affected by the quality of the PAN fiber,and it also influence the production yield and cost. In general,the quality stable PAN fiber 2.2kg can produce the 1kg carbon fiber,but the low quality of the PAN fiber need more 2.5kg to produce 1kg carbon fiber,and the quality is also not stable.

The carbon carbon composite material is made of carbon matrix and reinforced carbon fiber,the whole system is consist of carbon element,the extremely strong attractive force make the material very stable. Under very high tempterature,it still can maintain solid,especially under the 2500 centigrade. And the mechanical strength will increase with the growing of the tempterature,and the chemical composition does not change. The carbon carbon composite material is the best high temperature resistant material.

　　The 3D and 4D structure of the C/C material has been successfully used for the nose cone and nozzle. Strategic missile and anti missile reentry nose cone are made from the C/C composite material,and the structure is 3D material. Because of the accuracy requirements,the missile need the material no loss even under the high tempterature,and the carbon carbon composite material has the property,so it can be widely used for this.

　　Now among the strategic weapon,3D carbon carbon composite material is the most commonly used,and the production and technology is also the most mature. And the second one is 4D carbon carbon composite material,in addition ,2D carbon carbon composite material is also widely used in the engine diffusion section. The carbon carbon composite material is a promising high temperature resistant material in the future.

　　The reentry environment of ballistic missile is very poor. So the 3D structure is mostly used to increase the property of Z axis,and it can improve the erosion,and to overcome the problem of mechanical erosion occurring frequently in the severe reentry environment.To the 3D reinforced composite material, there is no weak link in any direction.

　　The presence of carbon fiber composite material is since sixty time,as it can be used for missile and astronavigation, many scholars were interested in it very much.