Pistons for internal combustion engines have been made of such materials as cast iron, steel and aluminum. Most pistons manufactured today are made of aluminum. However, aluminum has low strength and stiffness at elevated temperatures, and aluminum has a large coefficient of thermal expansion. A new piston concept, made of carboncarbon refractory-composite material, has been developed that overcomes a number of the shortcomings of aluminum pistons. Carbon-carbon

　　material, developed in the early 1960's, is lighter weight than aluminum, has higher strength and stiffness than aluminum and maintains these properties at temperatures over 2500°F. In addition, a low coefficient of thermal expansion and a high thermal conductivity give carbon-carbon material excellent resistance to thermal shock. An effort, called the Advanced Carbon-Carbon Piston Program was started in 1986 to develop and test carboncarbon pistons for use in two-stroke-cycle and fourstroke-cycle engines. The carbon-carbon pistons developed under this program were designed to be replacements for existing aluminum pistons, use standard piston pin assemblies and use standard ring sets. The purpose of the engine tests was to show that pistons made of carbon-carbon material could be successfully operated in a two-stroke-cycle engine and a four-stroke-cycle engine.

　　Carbon-carbon pistons can potentially enable engines to be more reliable, to be more efficient (lower hydrocarbon emissions, greater fuel efficiency), and to have greater power output. By utilizing the unique characteristics of carbon-carbon material -- very low expansion rate, low weight, high strength and stiffness at elevated temperatures, and high thermal conductivity -- a carbon-carbon piston can (1) have greater resistance to structural damage caused by overheating, lean air-fuel mixture conditions and detonation, (2) be designed to be lighter-weight than an aluminum piston thus, reducing the reciprocating mass of an engine, and (3) be operated in a higher combustion temperature environment without failure.

　　Carbon fiber reinforced C-SiC composites have a series of excellent properties, such as high temperature resistance, high specific strength, high specific modulus, low thermal expansion coefficient, excellent high temperature thermodynamic stability and so on.

　　It also has the characteristics of high density, heat shock resistance, ablation resistance and thermal chemical stability. It is a new type of composite material with high temperature resistance and high temperature, and is also a new type of high temperature resistant material, such as aerospace, advanced energy system, high temperature heat exchange system, etc.

　　In the existing preparation process, molten silicon infiltration reaction method (liquid silicon infiltration, LSI) due to the short preparation period, low cost, can realize net shape forming advantages, has great potential for development, has been extensively researched at home and abroad.

　　It can be realized by adjusting the microstructure of the preform to control the performance of C/C-SiC composites.

　　By high temperature heat treatment to C fibers of may effectively, change the C / C preform pore distribution, pore size and porosity, the main reason is the surface structure of the fiber is changed by the heat treatment, surface functional groups changed, resulting in combining the strength change of the fiber / matrix interface.

　　Carbon fibers after heat treatment, surface containing oxygen functional groups decreased, resulting in CFRP precursor fiber / resin interface bonding strength becomes weaker, thereby increasing the porosity of C / C preform and cracks / holes were mainly distributed network, by liquid silicon infiltration of C / C-SiC composites prepared by the density increased, the increased of SiC matrix, wrapped around the carbon fiber, distribution is uniform.

　　Carbon carbon composite material is carbon fiber reinforced carbon matrix composites, with high strength, high modulus, high dimensional stability, high conductivity, high fracture toughness, low density, heat expansion coefficient is small, thermal shock resistance, ablation resistance, chemical inertness and a series of advantages, as a new type of resistance material for high temperature structural and functional integration engineering development rapidly.

　　At present, widely used in aerospace aircraft structural materials, solid motor nozzle, civil, military aircraft and racing friction brake materials, as well as biological engineering structural materials.

　　At first because of the relatively high price of C / C composites limits its application in the field of industrial, in recent years, with the carbon fiber raw material and manufacturing cost reduced, C / C composites manufacturing technology and high-tech industry demand, it by the aerospace field gradually into the industrial field, used to replace the other materials.

　　Now, the silicon furnace lining, lining board, heating body, heat insulation screen, flow guide tube, crucible and other important thermal field components are manufactured with high purity graphite. But the strength of graphite is low, the brittleness is big, and it is easy to crack under the action of alternating thermal stress and electromagnetic force.

　　Using C / C composite design and manufacturing of thermal field component has excellent mechanical properties, and is resistant to vibration, ablation resistance and comprehensive performance is much better than that of graphite. The wall thickness of the thermal field is much thinner than that of the graphite piece (C/C single crystal silicon furnace thermal insulation liner, the thickness is only 3 ~ 5 mm, and the corresponding graphite parts need 10 mm). The space occupied by the components is small, the quality of the heat field component is reduced, the thermal inertia of the equipment is reduced, and the service life of the parts is greatly improved due to the good performance of the C/C material. Therefore, it is necessary to make the C/C composite material instead of graphite.

　　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 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.

　　By changing the machining method of the carbon carbon composite material,the C/C nozzle can meet CNC machining,it can avoid the various defects made by manual processing,improve the qualified rate, increase the workshop processing ability.

　　Nowadays,carbon carbon composite material is the main development trend of tactical missile throat material,the high-property carbon carbon composite nozzle is mostly made of 4D C/C material.

　　The carbon carbon composite nozzle in the SRM has a high property requirement,mainly include ablation resistance property,high stability,machinable and can be mass production,now it need low cost.

　　The normal turning machine is low machining accuracy and influenced personaly too much,the machining surface is not uniform,to confirm the quality of the carbon carbon composite nozzle,it should be processed more accuract.

　　The first influence of machining is the different programming,in addition, the geometry of the tool also have an influence on the machining,the right way to choose the tool can reduce the influence of the material properties, as the low density of carbon carbon composite material(1.85~1.98g/cm3),the most suitable angle of the tool is from 18 degree to 20 degree.

　　As the multidimensional programming C/C composite material nozzle has particularity and complexity, the machining of the nozzle should consider about the structure of the Weaving.

　　The choosing of the tool should combine with the technology data,after improving the machining technology, different size of the nozzle can be qualified processing.

　　With the requirement of the nozzle material increasing,the nozzle need the material with higher properties,more stable,and the better ablation resistance. The Z axis carbon fiber content of acupuncture and puncture C/C composite material increase,the strength property of the material also increase,and the structure is better,the carbon perform can also meet mass production,it can make meet the low cost production.

　　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.