Carbon carbon composite material is a new type of high temperature material, with light weight, high modulus, high specific strength, low thermal expansion coefficient, high temperature resistance, heat shock resistance, corrosion resistance, good vibration absorption and so on.

　　In the application, as an anti ablation, short time use of the material, carbon carbon composites have been successfully applied in the aerospace industry, such as rocket engine exhaust nozzle, throat lining, aerospace aircraft wing leading edge and so on. In the field of aerospace applications, the most successful example when the number of carbon carbon composite material brake disc, in this area has formed a mature market.

　　Carbon carbon composite brake disk advantages mainly due to its own density, high temperature resistant characteristics, because its density is small, the use of carbon / carbon disk and can greatly reduce the weight of each aircraft. An aircraft brake friction caused by the temperature rise of more than 500, at this time, the high temperature resistance of carbon carbon material shows great superiority.

　　In order to solve the oxidation of carbon / carbon materials, the effects of matrix modification on the oxidation resistance of SiO2, ZrO2, Al2O3 and so on.

　　Carbon carbon composite material is not used for rotating parts of the engine yet, the reason is mainly antioxidant problem, the traditional design will not be suitable for carbon carbon composite materials, must be based on the characteristics of the material to carry out a special, new structural design.

　　The application prospect of carbon carbon composites is very attractive, but it is still dependent on a series of key problems to solve the key components of the aircraft engine.V

The carbon carbon composite material mainly consists of carbon fiber and carbon matrix two parts. The rational design can control the strength,thermal and physical properties of the carbon carbon composite material etc. and make it meet the production requirement on the direction and dimension. The function of the carbon matrix is fix the structure and direction of the carbon perform, and make it into continuous phase,and when it is under load,the carbon matrix can transfer the load to the carbon fiber. In addition,the carbon matrix can increase the density of the carbon carbon composite material,and reduce the porosity, it can protect the perform under the ablation and oxidation environment. The carbon matrix not only can change the properties of the carbon carbon composite material,but even can control the properties of the material. So the research of carbon fiber and carbon matrix influence to the C/C composite material is very important.

As the carbon fiber arrangement and the structure of carbon matrix are different,so the carbon carbon composite has an apparent anisotropy. According to some research,the testing samples are needle felt and fine needle aspiration,the result about the ablation is: the ablation rate in the X-Y is lower than the Z direstion,it means the ablation from different direction of the C/C material is different. Under certain condition,the property of fine needle aspiration is worse than the needle felt,and the fiber density of Z axis decides the ablation ,the higher fiber content means the lower ablation,and the ablation property is better.

The different kinds of the carbon matrix also has an influence to the ablatioin property of the carbon carbon composite material. The carbon matrix kinds devide into resin base,pitch base,and pyrolytic base etc.and mixed base. With the density of pyrolytic carbon increasing, the thermal conductivity and the strength property will increase accordingly.

　Carbon carbon composite material has the similar properties as the graphite material,such as low density,high-thermal resistance,ablation resistance,high strength,good thermal shock resistance and easy designed etc. meanwhile it also has some other properties which graphite material doesn’t have,such as brittleness of polycrystalline graphite,and the easy layering property of the pyrolytic graphite. Now the carbon carbon composite material is the most appropriate material used for the throat,nozzle of the rocket engine.

　　The carbon carbon composite material consists of two parts: carbon fiber perform and the carbon matrix. The structure of material decides the property of it. To the C/C composite material,as for the anisotropy,the structure and the performance of the material is very complex.

　　The property of carbon carbon composite material is decided from the property of carbon fiber,carbon matrix,and the interfacial properties of the fiber and carbon matrix. The carbon fiber is the base of the carbon carbon composite perform. The thermal property,strength property and the physical property can be designed and controled according to the different structure parameter,the parameters mainly include:the direction of the carbon fiber,the content of the carbon fiber,the space of the arrangement,the density of the carbon matrix,the type of the carbon fiber etc. With the dimension of carbon fiber structure increasing,the anisotropic of C/C material will decrease,and the strength of the material will increase,and the ablation performance of different direction will be more and more symmetry. However,with the dimension of the fiber increasing,the cost of the perform will be much more expensive,and it will be harder to densify.

　　The multi dimensional braided or acupuncture is to improve the Z axis or other non X-Y axis strength and thermal property of the carbon perform. But the cost of multi dimensional is too much ,and the hole in the embryo is bigger,it’s not easy to use CVI to meet a higher density. This kind of the perform is mostly used for the throat of the missile and rocket engine.

　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.

　　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.

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.

Carbon carbon composite material(C/C) is highly valued by advanced technology research personnel,and till now,the carbon carbon composite material is still the main material of the strategic missile and solid rocket motor nozzle

　　The carbon carbon composite material is carbon fiber reinforced matrix,is make the carbon fiber as the reinforced material,and make the carbon as the matrix,and use the processing and carbonization process to meet all carbon composite material. The carbon content of the carbon carbon composite material can be above 99% after high thermal processing. And it has many good properties.

　　The density of carbon composite material is very low(<2.0 /cm3),it’s the 1/4 of Ni,1/2 of ceamic,it’s very important to some structure which has a light requirement. The high thermal performance of carbon carbon material is good,the strength of it can be stable under the 2200 centigrade,and even higher than this. This performance is good that other material can not meet.

　　The alation performance of carbon carbon composite material is the main property, and it’s the main reason of it to be used in the aerospace industry. If it’s in the situation of period of time ,the tempterature can meet 3000 centigrade.

　　The friction resistance of carbon carbon composite material is also good,the friction coefficient is low,and the property is stable,it’s the best material to be used for friction.

　　It also has some other property,such as high specific strength, specific stiffness and high specific modulus etc.

　　The development of the carbon carbon composite material experienced four stages,1, the basic research stage of carbon fiber and dense process,1961~1964,Japan and English produce the carbon fiber with PAN,reduce the cost of carbon fiber.2, C/C composite material has been a greatly developed during seventies,the multi direction knitting technology and high pressure liquid phase impregnation and CVI was published. And use these methods to make the high density C/C composite material. 3, the carbon carbon composite material was used in the space shuttle during eighties to be antioxidant. 4,and now, most researches are on how to reduce the cost and new technology.