The main factors of the influence of the carbon carbon composite material include the type of carbon fiber, volume fraction and the type to reinforce,the type and structure of the matrix carbon,material density and the heating temperature(graphitization) etc.the mechanical property of the carbon carbon composite material will increase with the increasing of the density,but the heating will reduce the strength of the C/C composite material.

　　As to the densification process of embryo body is different,so the mechanical property of carbon composite material is usually different,different scolars will get different results.In general, we think that CVI carbon and the carbon fiber can form a good combination,so the CVI can make the carbon carbon composite with a better mechanical property than the liquid phase impregnation.

　　Actually ,no matter CVI or liquid phase impregnation to treat the carbon carbon composite material,the structure of the matrix carbon has a great influence on the mechanical property,so to the C/C composite material used aviation brake,the design of matrix carbon is very important to the mechanical property.And the processing of the matrix carbon also need to consider the cost of the raw material and other properties,like heating conductivity and the friction property.

　　The volume fraction of the the carbon fiber is also a very important parameter.if the content of the carbon fiber too short,the function of the carbon fiber is hardly to show up.the mechanical property of the C/C composite material will increase with the increasing of the carbon fiber content,when it reach to a certain limit,the property will reduce will the increasing of the carbon fiber.

　　To the carbon composite material with CVI processing,another influence is the structure of the CVI carbon.but the research on this part is short,especially for the 2D and 3D C/C composite material.the influence of the CVI carbon to the carbon carbon composite material need the further research.

　　The physical properties of carbon/carbon composite material are mainly included:density, degree of graphitization,hardness, thermal conductivity, electric conductivity, specific heat, coefficient of thermal expansion etc.Among these properties,the density,thermal conductivity and the graphitization are very important to the carbon carbon composite material which is used for aviation brake.

　　The density can be the direct response of the C/C material,and it’s the basis of other properties,and the density depends on the density of the carbon fiber and the matrix carbon and the porosity.

　　The degree of the graphitization is another important parameter of the C/C composite material,it has a close contact with the strength and friction property.now,there is no uniform method to test the graphitization degree,the ways to test it are mainly included XRD, laser Raman spectrometry, magnetic resistance method, electrical resistivity method etc.

　　The thermal conductivity is also important to the carbon carbon composite material,it’s a symptom during the heat absorption and heat release. In the brake process,the C/C material must have the ability to absorb and release much heat to make the brake device work well.the thermal conductivity of C/C material depends on the carbon fiber and matrix carbon,and the structure, density ,and the graphitization also have a contribution to the thermal conductivity. The volume fraction and the direction of the carbon fiber have a big effect on the thermal conductivity of the carbon carbon composite material.Some researches show that the larger density can lead to a higher thermal conductivity.

　　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

　　1.carbon/carbon composites, refers to in carbon fiber (or graphite) and its fabric as the reinforced material, carbon (or graphite) as matrix, through processing and handling all the carbon composite material made of carbide.

　　Carbon/carbon composite material is carbon fiber reinforced carbon composites, light quality, good erosion resistance, good thermal shock, high damage tolerance, high temperature and high strength, can be designed as a prominent feature, is used in aviation, spaceflight, circuit level and the production of solar energy silicon, high temperature furnace and other applications.

　　2. carbon - carbon composite material performance characteristics

　　(1) physical properties: C/C composites at high temperature after heat treatment, the chemical composition of carbon element is higher than 99%, low density, with strong affinity, high melting point, due to carbon with high temperature resistance, corrosion resistance and thermal shock performance good characteristic, acid, alkali, salt.

　　(2) mechanical properties: reflect the mechanical behavior of C/C composites is strength and modulus of elasticity, resistance to friction and wear performance is good.

　　(3) the high temperature stability: C/C composites at room temperature strength can keep up to 2500 ℃, is not sensitive to the thermal stress, ablation resistance performance is good.

　　(4) comprehensive performance evaluation: C/C composites at room temperature strength and elastic modulus, good production C/C composites link, saves materials and manufacturing cost, safety and high reliability.

　　3. carbon carbon composite material manufacturing technology

　　In the choice of technology to the preparation of C/C composites, should according to the requirements of the C/C application first choose to use what kind of fiber and matrix, and then determine the preparation of the fiber and matrix material to be used.

　　(1) carbon fiber preparation technology, the preparation of carbon fibers using different raw materials, the process is slightly different. If use polyacrylonitrile, acrylonitrile polymerization, spinning, used as flame treatment, carbonization, eventually forming products. If use asphalt, coarse asphalt refining, melt spinning, the final carbonization. The quality of C/C first depends on the quality of carbon fiber.

　　(2) weaving technology: weaving techniques can be divided into one-way weaving and knitting garment. Weaving for at least 2 to garment, to up to 11. Also can be divided into machine weaving and knitting. And subdivided into radial knitting machine and weft knitting. Machine knitting technology was unable to get their products fluff or break easily and widely used; Hand-woven technology because of its product does not exist the faults of knitwear and widely used at home and abroad. Currently use more is wound by hand woven and cross weaving, more advanced weaving is targeted.

　　(3) technology: the formation of woven textiles after for the densification process. Dense technology is divided into liquid impregnation, solid immersion and gas impregnation technology. The current application more is chemical vapor deposition technology.

　　(4) the development of the technology: chemical vapor infiltration process, computer simulation, the C/C composite material density technology, carbon/carbon technology.

　　TE. GW GROUP LTD focus on the production carbon carbon composite material, We have customers all over the world, we have very good reputation, product quality is proved by customers.

　　If you have any enquiry, please feel free to contact us