Which Is More Fireproof? Carbon Fiber VS. Aramid
Introduction
When it comes to the field of materials engineering, there are two materials that have been extensively researched for their strength and performance characteristics; carbon fiber and aramid. These two materials are used extensively in various spheres, distinguishing themselves by their strength, durability, and resistance to general wear and tear. In recent times, there has been a marked interest in understanding the fire-resistant performance of these materials and how they fare when put through rigorous testing. While both materials have been found to be highly resistant to fire, this article seeks to comprehensively examine the differences between the two concerning their fire resistance properties and the performance of carbon fiber and aramid in different situations.
Carbon Fiber
Carbon fiber, also known as graphite fiber, is a popular substance used widely in the aerospace industry, sports equipment, automotive, and medical applications, among various other fields due to its exceptional durability and strength (Wang, Gao, & Cheng, 2016). Carbon fibers are created by polymerizing acrylonitrile in plants where it is electrospun and twisted into microfilaments, which then undergo carbonization. This process involves subjecting the filaments to extreme temperatures of up to 2,400°C, leading to the production of pure carbon atoms arranged in a crystalline lattice structure. The result is a material that boasts high tensile strength, low thermal expansion, and high resistance to chemical corrosion (Wang, Gao, & Cheng, 2016).
Apart from its exceptional mechanical properties, carbon fiber is known for its ability to tolerate high temperatures. It is considered stable up to 400°C in air and can endure up to 1,000°C in a vacuum without showing any signs of damage (Abdallah et al., 2018). However, once exposed to a direct flame, carbon fibers break down, typically resulting in melting or ignition. This is because at temperatures above 400°C, the carbon atoms in carbon fibers react with atmospheric oxygen to produce carbon monoxide and dioxide, which leads to the combustion of the material.
Aramid
Aramid fibers or aramids are high-performance synthetic fibers used extensively in various applications that require high strength, durability, and resistance to external elements. The most common type of aramid is poly-p-phenylene terephthalamide, known better as Kevlar, introduced in 1971 by DuPont. aramid fibers are produced by polymerizing molecules using a two-step reaction that includes first the creation of a liquid crystalline polymer through solubilizing and spinning into fiber form later. The finished fibers are distinguished by their high tensile strength, low elongation at break, and resistance to abrasion and impact (Zhou et al., 2018). The fibers are known for their exceptional thermal stability and can withstand temperatures of up to 300°C without damage.
Unlike carbon fiber, aramid fiber is also flame retardant, a characteristic that places it ahead of other materials in terms of fire resistance. When aramid fibers come into contact with a heat source, they undergo a process known as endothermic degradation, which causes the fibers to decompose without releasing any combustible gases (Zhou et al., 2018). Due to the absence of combustible gases, the rate of heat transfer to the substrate when aramid fibers experience fire is low, resulting in reduced intensity and lower damage.
Comparison: Carbon Fiber and Aramid in Fire Resistance
Although carbon fiber and aramid fiber are both known for their strength, durability, and resistance to external elements, they differ when it comes to fire resistance. Carbon fiber is prone to melting or ignition when exposed to fire, while aramid fiber tolerates heat and flame, making it an ideal material for applications involving high heat exposure (Jeong, Lee, & Kim, 2018). Additionally, aramid fiber exhibits exceptional mechanical properties even in the harshest of heat environments, making it the preferred material in the manufacturing of protective gear in the military, industrial, and firefighting industries.
In assessing the fire resistant performance of the materials, studies show that aramid fibers fare better than carbon fibers in situations that require protection from fire. In a study conducted by Li and coworkers (2019), the researchers subject both carbon and aramid fibers to a range of heat levels to determine the effects of heat exposure on the materials. The study found that while aramid fibers did not experience any significant changes when exposed to temperatures of up to 600°C, carbon fibers presented significant surface melting, cracking, and expansion. Similarly, in another study, Jeong and coworkers (2018) investigated the fire-resistant properties of the two materials with carbon fiber versus aramid fiber composites. The researchers found that the aramid fiber composite had superior flame resistance compared to the carbon fiber composite.
Furthermore, aramid fibers are more innovative in terms of design applications than carbon fiber. Since aramid fibers are inherently flame-retardant, the material is highly sought after in the textile industry for various applications, including firefighting gear, industrial personal protective equipment (PPE), outdoor clothing, and tents, among various others. Carbon fibers are not naturally flame-resistant, and any applications requiring fire resistance, such as engine components, require the addition of matrices to achieve flame resistance.
Conclusion
Overall, both carbon fiber and aramid fiber are exceptional materials renowned for their strength, durability, and outstanding performance characteristics. While carbon fiber is lauded for its exceptional mechanical properties, its fire-resistant properties are not on the same level with what aramid fiber has to offer. Aramid fiber is known for its exceptional thermal stability, flame retardance, and outstanding mechanical properties that make it ideal for use in harsh heat environments. Therefore, in applications requiring high performance under high heat environments, aramid fiber is the more preferred choice.
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