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

　　One way to decrease the ablation property of the carbon carbon composite material is add the coating which can be antioxidant and anti-scouring during the high temperature. Now the recognized method in the international community is HfC,TaC,ZrC and SiC etc. The technology mainly include CVI/CVD,CVR, liquid phase impregnation and coating. The C/C composite material throat made in Russia,using the Hf and Ta to dip into it,which can bear the 3800 centigrade and meet 8.0Mpa pressure,the ablation property is much lower than the normal carbon carbon composite throat.

　　The SiC coating C/C composite material can be made from two different kinds of the composite material matrix,one is needle felt reinforced material,using the CVD to densify to 1.3g/cm3 then using resin impregnant to meet density 1.8g/cm3 or even more than that,another way is puncturing reinforced matrix,the Si element is purity >99.3% and 300mesh Si powder,under the 1600centigrade high tempterature furnace,the Si steam has a chemical reaction with the C elecment,and meet the SiC coating on the surface of the C/C material.

　　During the ablation processing,the SiC coating reduce the ablation rate of carbon carbon composite material,and improve the ablation property,the SiC can have a protect fuction instantaneous.

　　Different working environment,the C/C composite material show different ablation morphologies,and meanwhile,it has the different ablation mechanism,generally speaking,the carbon carbon composite material used for SRM mainly affected by two aspects,one is thermal-chemical ablation and another one is mechanical denuding,the scouring of the grain can increase the changing of the thermal conductivity and strength and other strength,even break the structure of the material.when the different parts of the throat has the different ablation,then it will lead to the different ablation result.

　　Carbon carbon composite material can be used in the national defense industry and aerospace industry.

　　C/C composite material is made of PAN pre-oxidized fiber,use CVI and resin impregnation processing.it has a high specific strength,erosion resistance, thermal shock resistance,high temperature resistance,etc. After analogue simulation to the CVI processing of carbon carbon composite material and optimization of CVI processing,we could meet Computer automatic control of CVI processing and carbonization process,and reach the international advanced level.

　　In the early days,the solid rocket motor nozzle is made of graphite material and high strength steel or aluminium alloy,the weight of them increased costs and reduce the working efficienfy of the engine.with the rapid development of composite materials,the carbon carbon composite material replace the graphite material. The C/C composite material is light in weight and high strength,high temperature resistance,the developing trend in future is to make full carbon nozzle which means using carbon carbon composite material as integration structure material of the nozzle.

　　The throat is the main part of solid motor nozzle,the structure of it is sample,however,it’s the key parts. Among all the nozzle parts,the throat is in the worst environment,so the throat is easiest to be erosion. At present, high performance, large solid rocket motor nozzle general use carbon carbon composite material to make the throat.

　　The carbon carbon composite throat is now used in apogee kick rocket engine, medium range missile engine and II stage engine of long-range strategic missile,after the developing of multi direction weaving C/C composite throat,the I and III stage engine of long-range strategic missile can also made of it.

　　The failure behavior of carbon carbon composite throat is also important,the main factors include thermal contact resistance and ablation boundary, under the action of thermal stress, the fracture of the throat is broken.

　　Carbon/carbon composites is reinforced by carbon fiber and matrix carbon in two parts, according to the carbon fiber in the matrix form of carbon can be divided into the following three types:

　　The first: carbon fiber in the form of short fiber bundle randomly distributed in the matrix carbon.

　　The second: carbon fiber with continuous filament woven cloth, then composite laminated plates of forms exist in the matrix carbon.

　　The third: carbon fiber to between carbon cloth laminated plates and the transition between the two kinds of structure of 3 d braid structure, namely the form of a needled felt exist in the matrix carbon.

　　Carbon matrix according to its source and form can be divided into liquid phase method and gas phase method of two categories:

　　Such as liquid liquid phase method refers to use resin or asphalt. Carbon impregnated carbon fiber and solidification and carbonization, and organic matter removal of volatile organic matter composition, leaving the carbon composition, forming the matrix carbon composite material.

　　Gas phase method refers to the low molecular organic hydrocarbon through bake in a preheated in gas phase of carbon fiber reinforced body, and under the high temperature cracking and polymerization, forming the matrix carbon.

　　The distribution shape of carbon fiber reinforced, and the formation of the matrix carbon together, formed a variety of carbon/carbon composite material preparation pads, the actual use of the technology points of three categories:

　　The first category: short fibre moulded dipping carbonization process.

　　The process is first and foremost with resin impregnated carbon fiber filament formation of presoak belt, then cut short into a certain length of short fiber bundle, hot-pressing forming in the mold, after solidifying, carbonization treatment, reoccupy resin or pitch impregnation carbonization, and cycle times, until meet the requirements of material density. Finally after a certain processing to form carbon/carbon composites brake pads.

　　The process according to the coking pressure and other parameters can be divided into such as normal pressure, medium pressure and high pressure. The United States Honeywell and ABSC company mainly carbon brake was produced by the technology, its products are mainly applied in B767, MD11 aircraft, etc.

　　This process has the advantage of carbon fiber utilization ratio is high, the craft is simple, low production cost. The production of carbon/carbon composite material is isotropic state. Defect is low mechanical properties (see table 1), process in brake pad friction surface fracture phenomenon. The reason is for chopped carbon fiber reinforced body did not form a complete structure of the bundle. Another disadvantage is the wear rate is large, this is because the matrix carbon is ball, easy to form the abrasive abrasive wear.

　　The second category: carbon cloth laminated or needled felt precast body with chemical vapor deposition (CVD) process.

　　The process carbon fiber woven cloth first, then cut composite into prefabricated body or carbon fiber woven needle into needled felt kind of precast body, in the chemical vapor deposition in furnace using low molecular hydrocarbon deposits, until you reach the required density, finally after a certain processing to form carbon/carbon composites brake pads.

　　The process in the manner of precast body heat and air flow direction can be divided into isothermal constant pressure, differential pressure method, the temperature difference method, etc. Chinese bjgreatwall company can production

　　This process has the advantage of matrix carbon gradually grow along the carbon fiber surface and form, so closely matrix between carbon and carbon fiber structure. So the process of material mechanical properties of high (see chart 1). In addition, CVD carbon for the class of graphite layer structure, friction in the process of friction surface is easy to form a layer of graphite crystallite film, reduce material wear rate (see chart 1). The disadvantage is that the technology deposition efficiency is low, deposition time is long.

　　Third class: composite technology.

　　So-called composite process is the above two kinds of combination of preparation of carbon/carbon composites brake pads, such as the CVD process is the matrix of carbon fiber surface formed gradually grow. Suitable for smaller gap between the carbon fiber. Because big gap around small pore filling and block sedimentary gas source, formation of materials in the big hole, and dipping carbonization process, as a result of the impregnated resin or pitch carbonization is internal contraction form spherical matrix carbon, often out of contact with the surrounding carbon fibre, forming uniform small gaps. Big hole left by the CVD technology so easily be impregnated carbonized matrix carbon in small gaps formed between the fiber is suitable for CVD carbon offset. Can reduce the increase of the combination process time, improve production efficiency. The drawback is that process equipment complex, large investment. Adopting the technology producing carbon brake disc manufacturers have bjgreatwall company