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.

　　Carbon / carbon composite material are high temperature friction materials of excellent performance, as the brake materials have been successfully applied in aviation industry. But the friction and wear properties of carbon / carbon composite material strongly depends on the experimental conditions and preparation process.

　　Compared with other friction materials, carbon / carbon composite materials with low density, high temperature resistant, high strength, thermal shock resistance, corrosion resistance, good vibration resistance and suitable friction coefficient and friction performance, is a comprehensive performance excellent high temperature friction material.

　　Carbon / carbon composite material have become the preferred materials for aircraft brake discs. In France, for the civil aviation flying Airbus Company the machine brake system has been completely replaced by carbon / carbon plate steel plate; in the United States, many military aircraft have been using carbon / carbon brake disc, such as F-16, B-1 etc.

　　In addition to do the brake disc, carbon / carbon composite material can also be used as sliding bearing material and piston of internal combustion engine.Carbon / carbon composites as friction material will be used more widely.

　　Carbon / carbon composite material reinforced by carbon fiber and matrix for pyrolytic carbon, both of them are amorphous carbon.

　　The matrix type is one of the important factors affecting the friction and wear properties. In two different density of carbon / carbon composites, medium density of carbon / carbon composite has good friction performance, which has low coefficient of friction, the wear volume than low density and high density of carbon / carbon composite low one order of magnitude.

　　The carbon / carbon composite friction has a strong influence on Wear Properties of carbon fiber orientation. At low speeds, when the parallel fiber on friction surface, the wear rate is much lower than the fiber perpendicular to the direction of the friction surface to and friction coefficient fiber perpendicular to the direction of the friction surface is much higher than; at high speed, friction coefficient and wear rate are not big difference. Z to the fiber content increases, can improve the carbon / carbon composite thermal conductivity rate, reduce the friction surface temperature will also affect the friction and wear properties of carbon / Carbon Composites

　　Carbon carbon composite material is carbon fiber reinforced carbon matrix composites.

　　Carbon carbon composite material is derived from an unexpected discovery. In 1958, the United States VOUGHT CHANCE Laboratory,Carbon matrix was obtained from the carbon / phenolic experiment because of the failure of the operation. As a result, a new member of the composite family has been added.

　　The main preparation procedure of carbon carbon composite material is : preform molding, densifying and graphitization. Densification technology is the key technology of carbon carbon composite material. The densification methods of carbon carbon composite material are mainly divided into two categories: vapor deposition and liquid phase impregnation, liquid phase impregnation is divided into resin impregnation and asphalt impregnation.

　　The typical process of gas phase deposition: the prefabricated reinforcement is placed in a special gas-phase deposition furnace to be heated to the required temperature,through the pyrolysis of hydrocarbon gases, the carbon is deposited on the preformed carbon fibers and voids in the preform. The body is called the carbon.

　　In the gas phase deposition process, the main factors that influence the densification effect are the transmission speed and the change of the gaseous precursor.Learning reaction dynamics. The advantages of vapor deposition densification process is that the properties of the substrate are good, the degree of densification is easy to be controlled, the disadvantage is that the the production cycle is too long, the production efficiency is very low.

　　The typical process of resin impregnation process is that the prefabricated reinforcement is placed in the impregnation pot, and the resin immersion preform is used in the vacuum state,Then the resin is soaked through the whole preform, and then the prefabricated body is put into the curing tank to carry out the pressure solidification.

　　Carbonization under the protective atmosphere in the carbonization furnace. Due to the decomposition of non carbon elements in the carbonization process, the pre carbonization of the preformIn the formation of a lot of pores, therefore, the need for multiple impregnation, curing, carbonization, in order to achieve the desired effect of density.

　　Carbon carbon composite material due to its excellent thermodynamic properties has been widely used as solid rocket engine nozzle throat liner material, but graphite throat lining material due to the absence of carbon fiber reinforced, low strength, poor thermal shock resistance, low reliability; and multidimensional weaving and integrated felt carbon carbon throat lining, the complex production process, cycle is long, the production cost is higher.

　　Acupuncture has no weft fabric preform due to its internal alternating vertical layer straight pull carbon fiber, greatly improve material X - Y to the mechanical properties of, by paving layer between carbon fiber net fetal Z to acupuncture, improves the strength between layers of materials. The forming process of carbon carbon composite material with needle insertion without weft insertion is generally by impregnation of carbon precursor/ carbonation or CVI.

　　Thermal conductivity of carbon carbon composite material will determine its heat exchanging with the outside world and its own temperature change, its thermal expansion properties determine the size stability of its structure, which directly affects the stress distribution state and thermal shock resistance.

　　(1) before the pitch impregnation / carbonization of needled preform of CVI yejiyuzeng density, prepared by the method of carbon carbon composite material than not the forecasted and density of the specimens and the axial tensile strength improve 234% and interlaminar shear strength increased by 126%. At the same time, the material with higher thermal diffusivity and low axial linear expansion coefficient, showing a good comprehensive performance.

　　(2) compared to pure asphalt carbon based materials, CVI pretreatment of carbon carbon composite materials, the performance of non brittle fracture, fracture surface has a large number of fiber pull out, fiber play a toughening effect.

　　carbon/carbon composite material integrated carbon material of high temperature properties and composite materials with excellent mechanical properties, with high specific strength and high specific stiffness, excellent ablation resistance and friction performance, good thermal shock resistance, low creep, high temperature strength retention rate high and good biocompatibility and so on a series of excellent properties, it can be as functional materials, and can be used as high temperature structural materials, is currently the only composite material for high temperature of 2800.

　　So far, the carbon carbon composites have been successfully application in missile reentry nose cone, solid rocket motor nozzle, aerospace aircraft structure parts, brake disc, a heat exchanger, high power electronic device radiator and artificial bones, joints, teeth many fields, the development potential of large.

　　As the ideal candidates for high temperature structural materials, carbon carbon composite material in the service process inevitably relates to fatigue loading situation of fatigue damage of the gradual accumulation of will lead to a material in a certain number of cycles suddenly fracture, the fracture often no obvious signs, the harm is great, so the fatigue behavior research has very important significance, received extensive attention.

　　The fatigue behavior of carbon carbon composite material is not only related to the composition and structure of the material, but also with the test parameters, the different load and different loading frequency reflect the fatigue behavior.

　　The research on the fatigue behavior of carbon carbon composite material despite extensive attention, but still very limited, in order to promote carbon carbon composite material can as soon as possible from the laboratory into the practical application stage, a comprehensive understanding of the fatigue behavior is the focus of future research.

　　Carbon carbon composite material has a series of advantages under the high thermal condition,and it’s widely used in the aerospace field,however,the material will be oxidized rapidly in the aerobic conditions when the tempterature above 400 centigrade,and it will limit the using as the structure parts,protection material etc. And the coating technology is the good method to solve this problem.

　　SiC,ZrC material,as they have high melting point and good stable property under high tempterature, so they become the ideal material of protecting coating of carbon carbon composite material.

　　It can use the low pressure chemical vapor deposition(LPCVD) method to make the SiC coating and ZrC coating on the surface of carbon fiber and the inside C/C composite material. The different methods of this two material can be devide into SiC/ZrC mixed coating and SiC/ZrC/SiC multilayer coating, and it can improve the ablation property of the coating.

　　The mixed SiC/ZrC coating and the SiC/ZrC/SiC multilayer can improve thermal expansion mismatch between the ZrC layer and the carbon carbon composite material matrix,increase the ablation property of the carbon carbon composite material coating.

　　Missile, manned spaceship, space shuttle etc,most aerocrafts velocity is faster than the light speed,the tempterature around the aerocrafts will increase rapidly, and the tempterature on the surface of nozzle , aerofoil will above 2000 centigrade,except for these effects,there is the high speed particle flow on the surface, the normal material is hardly to bear all this bad environment. So the lighter weight material,high strength material and high thermal resistance material is needed.

　　Carbon carbon composite material is reinforced by the carbon fiber, and it’s made of the single element(carbon),low density,high strength,high modulus and good ablation property etc.meanwhile,the C/C material can bear the high tempterature, under the high tempterature,the material can still maintain the good properties.

　　The main method to increase carbon carbon composite material oxidation resistance are surface coating technology and carbon matrix modification. The traditional methods mainly include carbon fiber modification, liquid phase impregnation, additive agent, matrix replacement etc.

　　Carbon carbon composite material has low density, high strength,high modulus,high thermal conductivity,low coefficient of expansion and thermal shock resistance etc. These properties can maintain under the 2000 centigrade,can make the carbon carbon composite material to be the preferred material of high thermal structure material, and it’s widely used in the aerospace field. However,most of the properties can only maintain under the inert environment. Carbon carbon composite material will occure oxidation when the tempterature reach 400 centigrade,the oxidation can reduce the strength of the material,and will limit the using under the high thermal condition.

　　The surface coating technology now is the most widely used method,the coating can make the material work under 1600 centigrade,but the different coefficient of expansion of coating and the carbon carbon composite material make it will occur very small crack,and this make the coating will not work under the low tempterature.

　　The oxidation resistance technology of carbon carbon composite material mainly devide into carbon matrix modification and surface coating,the carbon matrix modification is different from the surface coating because of it will bring the oxygen barrier composition to the carbon perform,and make the carbon matrix with a oxidation resistance,and the oxygen barrier composition need a good chemical compatibility with the carbon matrix,and low penetration ability,and no influence to the properties of carbon carbon composite material.

　　Make the oxidation resistance on the carbon fiber surface can reduce the oxidation velocity and protect the C/C material. And there are two methods to modify the carbon fiber,one is making the coating on the surface of the carbon fiber ,and another one is gas phase treatment on carbon fiber surface.

　　Carbon carbon composite material used in the airplane is an advanced technology,and it’s already widely used in the aerospace field. The big difference between carbon Carbon brake disc and the other material is the material is used of carbon carbon composite material,it’s the heat reservoir,structure material and friction parts.

　　The advantage of carbon carbon composite material mainly includes: the light weight,high strength under the high thermal situation,and no distortion,good friction property and long service time,the density of C/C composite is 1/4 of the steel,it can make the Boeing-747-400 lose weight about 800kg. The carbon carbon composite material will not change on the surface and the structure under the 2000 centigrade,during the 3000 centigrade situation,the moudulus will increase with the temperature increasing,the working temperature can meet 2200 centigrade,the strength property of carbon carbon composite material is better than other material,and it has a high thermal conductivity and low C.T.E. the thermal shock resistance is better than other material.

　　The disadvantage of carbon carbon composite material is that the material is easy to be oxidized,and under the wet situation,the friction property is worse,the method to solve this problem is make the oxidation resistant coating on the surface of the C/C brake dics.

　　The way to manufacture the C/C composite material brake dics mainly devides into two methods,the difference between this two ways is the different carbon matrix,one is using the resin matrix, and another one is using the CVD pyrolytic carbon to make it. Both of this two methods have their disadvantage, to avoid this, the normal way is to using the mixed method.

　　The processing: carbon perform, liquid impregnation, carbonization+CVD,high thermal treatment,products.

　　Carbon carbon composite material is carbon fiber reinforced carbon matrix composite material,and it has a series of good properties,such as light weight,high specific strength,high specific modulus,high thermal resistance,low coefficient of thermal expansion,excellent friction property,and designable,the material now is already widely used for the nose cone and wing leading edge of space shuttle,nozzle throat and exit cone of SRM, nose-tip of missile,aircraft brake disc and high thermal mould etc.

　　Punctured structure carbon carbon composite material is one of the composite materials of C/C composite,the good properties includes:good isotropy property,strength property. And the strength property is mainly decided from the structure of carbon fiber perform. The X-Y direction of the punctured structure perform includes carbon fiber cloth and the carbon fiber net,make them composite laminate,and there are some punctured fasciculus along the Z direction.

　　Use the different gap,different quantity carbon fiber to make the carbon fiber perform,then CVI,pitch-impregnated and high pressure carbonization to densify,the tensile property testing result show that the different gap between puncture,different number of carbon fiber has an influence to the tensile strength,with the distance of the puncture reduce,the number of carbon fiber increase,the carbon fiber content along Z axis increase and all these influence can lead to the different tensile strength along the Z axis.

　　The tensile strength of the carbon carbon composite material is mainly decided from the carbon fiber,the densifying is the processing that carbon matrix filling the carbon perform,the porosity is because of the densifying processing,and this defect will lead to the destruction when there is a load on the products,the porosity will reduce the loaded area,and has an influence to the material.

　　The carbon carbon composite materials as excellent thermal structure, functional integration of Engineering materials, since its birth in 1958, it has been greatly developed in the military , the most important use is for the manufacture of missile warhead components. Due to its high temperature resistance, good wear. It has been widely used in solid rocket motor, aerospace structural parts of aircraft, aircraft and racing brake device, the heating element and mechanical fasteners, heat exchanger, aviation engine hot end components.

　　The properties of carbon carbon composites:

　　(1) The physical properties: the C / C composites after heat treatment in the chemical composition and elemental carbon higher than 99%, low density, has a strong affinity, due to the high melting point of elemental carbon, it has high temperature resistance, good corrosion resistance and thermal shock resistance, acid, alkali, salt.

　　(2) The mechanical properties: The strength, modulus of elasticity and friction and wear resistance performances are the mechanical properties of C/C composites.

　　(3)The high temperature stability: the room temperature strength of C/C composite can be maintained to 2500 C, the thermal stress of C/C composites is not sensitive, it has good resistance to erosion.

　　(4) The comprehensive performance evaluation: the strength and elastic modulus of C/C composite at room temperature is good, the production of C/C composite material is less, it can save material and manufacturing cost, it has high safety and reliability.

　　The research results show that the major factors which influences the thermal conductivity of carbon / carbon composites is the the microstructure of CVD pyrolytic carbon , in different CVD pyrolytic carbon , the CVD pyrolytic carbon which the main structure is the RL structure has the highest thermal conductivity; whether heat treatment of carbon / carbon composites thermal conductivity rate has considerable influence, but the heat treatment temperature increasing of carbon / carbon composite thermal conductivity is limited to improve.

　　The properties of carbon carbon composite not only has high specific strength, high specific modulus and other prominent structural material characteristics, but also has excellent friction and wear and thermal physical properties, it can well meet the high-speed jet aircraft brake materials. The carbon / carbon composite materials has become a new generation of prospects for the development of aeronautical materials. The air brake carbon / carbon composites on the microstructure is a heterogeneous mixture