Carbon fiber’s unique properties make it an ideal structural material for various applications in numerous industries. Carbon fiber composites have replaced standard structural materials (i.e. aluminum, titanium, and steel) in many existing applications and also enabled new applications and technologies.
Carbon Fiber: A Unique Material
Rigidity, strength, and fatigue resistance are some of the most impressive properties of carbon fiber. Composites containing the fiber are twice as stiff and five times stronger than steel per unit weight. Carbon fiber also has better fatigue properties and corrosion resistance than most materials including high-strength steel alloys.
Most carbon fiber is fabricated from carbon-rich polyacrylonitrile (PAN). Producing the fiber from PAN involves multiple steps, one of which is pyrolysis at 1500-3000⁰ C. This heat treatment changes the molecular structure of the carbon into layers of graphite. These graphite layers are formed from carbon atoms arranged in a 2-dimensional hexagonal ring pattern resembling chicken wire. The layers are packed tightly and aligned along the fiber axis.
The mechanical properties of the resulting fiber depend on the internal arrangement of these graphite layers which, in turn, is controlled by the pyrolysis process. Standard Modulus carbon fiber has a tensile modulus of approx 230GPa and a tensile strength of approx 4 MPa. The fiber can be processed to achieve a higher elastic modulus of 350-450 GPa but at a loss of tensile strength (reduced to approx 3MPa). Structures that require both high strength and high stiffness often utilize an intermediate modulus fiber.
The graphite fibers are embedded in a stable matrix, such as an epoxy resin, to form a carbon fiber composite. In addition to being strong, rigid, and lightweight, depending on the resin type the resulting composite may be chemically resistant, flame resistant, and exhibit a high-temperature tolerance with low thermal expansion.
A Raw Material in Industry
The aerospace industry was a leader in the use of carbon fiber, making great use of the material’s high strength-to-weight and stiffness-to-weight ratios. Today, industries producing such items as drones, construction materials, robotics, tactical ladders, and sporting goods are taking advantage of this versatile fiber’s rigidity and lightweight characteristics.
Medical and optical industries also utilize the unique properties of carbon fiber. Because it is biologically inert and permeable to x-rays, carbon fiber composites are ideal for use in prosthetics, implants, and surgical equipment. Medical imaging tables made from the fiber maintain critical dimensions even after high doses of x-ray and gamma radiation. Additionally, carbon fiber composites have low coefficients of thermal expansion (near zero) prompting their application in such products as telescopes, optical benches, and precision measurement tools.
The music industry is also finding applications of carbon fiber’s unconventional properties. Along with its high dimensional stability and resistance to humidity, carbon fiber exhibits low damping to vibration. This characteristic combined with high stiffness to weight can significantly improve the resonance of an instrument. Musical instruments made using carbon fiber offer a full, rich sound, provide greater acoustic volume, and are not affected by changes in ambient conditions.
A Tool in Industry
While many industries have found applications for carbon fiber in their end products, it is also important to note that this material plays a significant role within the manufacturing process. For example, tools made with carbon fiber composites can be 50% lighter than tools made from conventional materials. Inspection tools and machine parts that were previously moved with heavy equipment can be lightened with carbon fiber, making them easier to handle and move. Carbon fiber idler rolls are more rigid than steel rolls, resulting in reduced bending and yielding. These rolls require less power to run and allow for faster line speeds, as well as reduced friction on bearings.
Industries using robotics and other automated systems are replacing metal end effectors with carbon fiber composite ones. These replacement end effectors allow the automation to move faster and more precisely, lift heavier parts, and reduce the motor load on the equipment.
Carbon fiber technology continues to develop with the demand for higher performance. Element 6 Composites recognizes that this developing technology, combined with our innovation and creativity, can yield cost-efficient, high-performance products. Contact Element 6 Composites to discover how carbon fiber can play a role in your company’s growth and success.