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History of carbon composite brake pad
来源:隆宝山墓园   浏览时间:2014-12-29   浏览次数:2996次

  History of carbon composite brake pad

  Characteristics of 1 carbon / carbon composite brake pad

  Because of a series of unique mechanical, thermal and friction and wear properties, carbon / carbon composites have become a new generation of brake materials instead of metal matrix composites:

  Density is small, the density of the material in 1.8g/cm3 or so, is the metal matrix composites 1/3 to 1/4. Compared with the brake components produced by the material, the weight loss is about 40%. This military aircraft, the aircraft can improve the payload and technical indicators of war; for commercial aircraft, the 1Kg equivalent to the equivalent of a year to save 3000 liters of fuel. Therefore, its cost saving effect is remarkable.

  Good thermal stability, when the aircraft stopped after takeoff, the surface temperature of brake more than 2000 DEG C, carbon / carbon composites can not melt adhesive, no warping deformation, after cooling can continue to use; and the metal base composite material temperature exceeding 660 DEG C above will produce warping deformation, lead to melt adhesive, need to overhaul the brake assembly. Therefore, the use of carbon / carbon composite brake pads not only improve the design margin of the brake components, but also improve the safety of the use of the brake components.

  The specific heat capacity of the material is 2.5 times that of the metal matrix composite material, which has good heat absorption function, improves the heat storage capacity of the heat storage tank, and reduces the working temperature of the heat storage tank.

  The friction coefficient is stable, the material has a stable friction coefficient in a large temperature range, the aircraft braking process is soft, improve the aircraft braking comfort.

  Low wear rate, long service life. Up to 2 times more than metal matrix composites, reducing the number of maintenance of the brake components.

  High strength, especially high strength steel [1] is more than 2 times, compared with the metal matrix composites, the material itself can be used as structural elements, do not need other materials to make the frame support structure, simplifies the structure of brake assembly, brake assembly to improve reliability and maintainability.

  Because the material has the characteristics, especially suitable for the use of aircraft brake materials, so since the last century since 90s, carbon brake has become the standard configuration of the new aircraft and a wide range of applications.

  Basic production process of 2 carbon / carbon composite brake pad

  Carbon / carbon composites are made up of two parts: carbon fiber reinforcement and matrix carbon, which can be divided into three kinds according to the form of carbon fiber in carbon fiber:

  The first one: carbon fiber to short fiber bundle randomly distributed in the matrix in carbon. (currently mainly represented by the European and American brands such as Brembo)

  Second kinds of carbon fiber with continuous filament woven into cloth, and then form superimposed laminates in carbon matrix.

  The third kind of carbon fiber is the transition structure between two kinds of structures, which is a kind of carbon cloth laminate and three dimensional fabric. (a carbon ceramic, carbon carbon brake disc adopt this kind of Technology)

  The matrix carbon is divided into two types by liquid phase method and gas phase method according to its origin and form:

  Liquid phase method is used to refer to the liquid phase, such as resin or asphalt. Carbon impregnated carbon fiber and curing and carbonization, volatile components in organic matter removal, leaving the carbonaceous component, forming carbon matrix in composite materials.

  Gas phase method refers to the low molecular organic hydrocarbons in the form of gas through the preheating of carbon fiber reinforcement, and at high temperature cracking and polymerization, the formation of carbon matrix.

  The distribution shape of the carbon fiber reinforced body is combined with the formation of the basal body, and a variety of carbon / carbon composite materials are formed in the preparation process, the actual use of the process is divided into three types:

  The first kind: short fiber molding impregnation carbonization process.

  The first is the process with resin impregnated carbon fiber filament to form a prepreg tape, then cut into short staple tows a certain length, die in hot forming, after curing and carbonization treatment, using resin or pitch impregnation, and cycle times, until it reaches the required material density. Finally, the carbon / carbon composite brake pad is formed through a certain process.

  According to the parameters such as pressure, the process can be divided into normal pressure, medium pressure, high pressure and so on. The United States Honeywell company and ABSC company mainly uses the process to produce carbon brake, its products are mainly used in MD11, B767 and other aircraft.

  The advantages of the process are that the utilization rate of the carbon fiber is high, the process is simple and the production cost is low. The carbon / carbon composites produced are isotropic. The disadvantage is that the mechanical property is low (see Table 1), and the friction surface of the brake pad is easy to be broken in the process of using. The reason is that the carbon fiber reinforced body is the short cut fiber bundle, which has not formed the complete structure. Another disadvantage is that the wear rate of large (see Table 1), this is because carbon matrix is spherical, easy to form abrasive abrasive wear mode. (currently mainly represented by the European and American brands such as Brembo)

  Second types: carbon cloth laminate or needle felt preform and chemical vapor deposition (CVD) process.

  This process first carbon fiber woven carbon cloth, cutting the laminated preform or carbon fiber woven into a kind of acupuncture needle felt preform, deposited with low molecular hydrocarbons in the furnace in a chemical vapor deposition, until it reaches the required density, finally after processing the formation of carbon / carbon composite brake.

  The process in accordance with the preform heating method and flow direction can be divided into constant pressure and pressure difference method, temperature method etc..

  U.S. Goodrich company, the United States Dunlop company, France Messier company using the process to produce carbon brake pads, the product is mainly used for B757, B747-400, Airbus series, such as [2].

  carbon carbon composite, graphite, graphite felt  http://www.cfccarbon.com/

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