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Analysis of the physical properties of carbon fibers

文章标签:carbon fiber, the physical properties of carbon fibers

Both strong carbon fiber carbon materials tensile strength and fiber soft workability two features, is one excellent mechanical properties of the new material. Carbon fiber tensile strength of about 2 to 7GPa, tensile modulus of about 200 to 700GPa. A density of about 1.5 to 2.0 grams per cubic centimeter, which in addition to the structure of the original wire, the temperature is mainly determined in the carbonization process. Usually after 3000 ℃ high temperature treatment of graphite, density of up to 2.0 grams per cubic centimeter. Along with its light weight, its specific gravity is lighter than aluminum, 1/4 strength steel is 20 times less than iron. Thermal expansion coefficient of the carbon fibers with other fibers different, it has anisotropic characteristics. The specific heat capacity of carbon fiber is typically 7.12. Thermal conductivity decreases with increasing temperature parallel to the fiber direction is negative (0.72 to 0.90), and perpendicular to the fiber direction is positive (32-22). Carbon fiber ratio is related to fiber type resistance at 25 ℃, 775 high modulus, high strength carbon fibers per centimeter 1500. This makes the carbon fiber has the highest specific strength and modulus of all high-performance fibers. Compared with titanium, steel, aluminum and other metal materials, carbon fiber on the physical properties has high strength, high modulus, low density, linear expansion coefficient, etc., it can be called the king of the new material.

In addition to the general properties of the carbon fiber having a carbon material, its appearance has a significant anisotropy soft, processed into a variety of fabrics, but also due to the small proportion of the fiber axis direction exhibits high strength, carbon fiber reinforced epoxy resin composites material, its specific strength and specific modulus composite indicator, the existing structural materials is the highest.

Carbon fiber resin composite tensile strength 3500 MPa or more generally, is 7-9 times that of steel, the tensile elastic modulus of 230 Pa to 430G also higher than steel; thus the intensity of CFRP specific strength that is material to its density It can reach more than 2000 MPa or more, and A3 steel strength only about 59 MPa, which is higher than the modulus than steel. Compared with conventional glass fiber, the Young's modulus (refer to characterize the elastic limit of the material quantities for Tension or compression) is more than three times of the glass fiber; Kevlar compared with not only the Young's modulus which is about 2 times. Carbon fiber epoxy laminates tests showed that with the increase of porosity, strength and modulus decreased. The porosity of the interlaminar shear strength, flexural strength, flexural modulus of very large; tensile strength decreased with increasing porosity is relatively slow; tensile modulus less affected by porosity.

Carbon fiber also has excellent fineness (fineness of one notation is 9000 m long fiber in grams), generally only about 19 grams, pull up to 300kg per micron. Almost no other materials like carbon fiber that has so many series of excellent performance, so the purpose of, stiffness, and severe fatigue properties, which are areas of strict requirements. When not exposed to air and the oxidant, the carbon fibers can withstand temperatures above 3000 degrees, with outstanding heat resistance, compared with other materials, the carbon fiber to a temperature higher than the strength at 1500 ℃ began to fall, and the higher the temperature, the fibers The greater the intensity. Radial strength of the carbon fiber is not as axial strength, carbon fiber and thus avoid radial force (ie not tie) and the performance of other whisker materials have long been greatly reduced. Further carbon fiber also has good low temperature properties, such as at liquid nitrogen temperature is not brittle.