Pitch-based carbon fiber is a carbon fiber material made from petroleum asphalt or coal tar asphalt. It is characterized by abundant raw materials, low cost, high carbonization rate, and low product cost. High-performance pitch-based carbon fiber has outstanding tensile modulus and excellent conductivity, making it suitable for use as a functional material or as a reinforcing fiber in composite materials.
Performance Characteristics of Pitch-Based Carbon Fiber
Pitch-Based carbon fiber exhibits high modulus, high thermal conductivity, low thermal expansion coefficient, and other superior properties. Its modulus can reach over 900 GPa, approaching approximately 92% of the theoretical value. This high modulus characteristic enables pitch-based carbon fiber to perform exceptionally well in applications requiring high rigidity, such as aerospace structural components and sports equipment. Pitch-based carbon fiber has extremely high thermal conductivity, ranging from 600 to 1100 W/(m·K), far exceeding that of metals like aluminum and copper. This property makes it highly valuable in thermal management systems, such as in electronic device cooling and thermal protection for high-speed aircraft.
Pitch-based carbon fiber has an extremely low thermal expansion coefficient, capable of achieving zero expansion or even negative expansion. This provides greater design flexibility for materials requiring high stability, particularly in environments with significant temperature fluctuations. As a carbon fiber material, pitch-based carbon fiber possesses lightweight properties, which are crucial for applications requiring weight reduction, such as aerospace and automotive lightweighting. It also exhibits excellent electrical conductivity, giving it advantages in applications requiring conductivity or static dissipation, such as electromagnetic shielding materials.
Although pitch-based carbon fiber may not match the strength of PAN-based carbon fiber, it still possesses sufficient strength to meet the requirements of most structural applications. Additionally, asphalt-based carbon fiber exhibits excellent corrosion resistance, fatigue resistance, and processability, and can be fabricated into various composite materials through multiple methods such as weaving, winding, and lamination.
Pitch-based carbon fiber classification
Pitch-based carbon fibers can be classified into two categories based on their mechanical properties: the first type is general-purpose carbon fiber produced from isotropic asphalt, also known as isotropic pitch-based carbon fiber. It exhibits structural non-uniformity, featuring both regions with high-order crystalline structures and regions with lower-order amorphous structures. The production process for general-purpose carbon fibers is relatively simple, but their mechanical properties are inferior, with tensile strength lower than that of PAN-based carbon fibers. However, they are cheaper than PAN-based carbon fibers and have widespread market applications, particularly as functional materials. The second type involves modifying isotropic asphalt to create an intermediate-phase asphalt with anisotropic properties, from which high-performance carbon fiber materials are produced, known as intermediate-phase pitch-based carbon fibers. The plate-like or disc-shaped molecules in intermediate-phase pitch undergo shear forces during the textile process, forming an oriented arrangement. The high-performance carbon fibers produced contain layered graphite microcrystals with an oriented matrix, whose planes are parallel to the carbon fiber axis, exhibiting excellent mechanical properties, particularly with tensile modulus typically exceeding that of PAN-based carbon fibers.
Based on filament bundle size, pitch-based carbon fibers can be classified into small filament bundle carbon fibers and large filament bundle carbon fibers. Small filament bundle carbon fibers typically refer to carbon fibers with fewer filament bundles, suitable for specific high-performance applications. Large filament bundle carbon fibers refer to carbon fibers with more filament bundles, which are cost-effective and suitable for large-scale industrial applications.
Based on product form, pitch-based carbon fibers can also be classified into continuous filaments, short fibers, and chopped fibers.