The phrase “carbon fiber” has several meanings. In popular culture, it usually means any product that is made with carbon fiber or a product made with a material that looks like carbon fiber. In the composites industry, carbon fiber is one of several fiber reinforcement types used to manufacture a composite part or structure. A composite, in turn, is a part or structure that combines a fiber reinforcement with a polymer resin of some sort. It’s this combination of fiber and resin that gives a composite its strength, stiffness and durability properties. In the composites industry, we usually specify the fiber used in a given composite part. So, we say “carbon fiber composite” or “glass fiber composite.” To the layperson, use of the phrase “carbon fiber” usually means carbon fiber composite — carbon fiber combined with a resin (usually epoxy).
How long does carbon fiber last?
Carbon fiber by itself, although a remarkable material, does not have unusual durability properties. However, when carbon fiber is combined with a resin to create a carbon fiber composite, it has strength, stiffness, and durability that are nearly impossible to match with any other material.
Carbon fiber composites don’t rust or corrode the way metals do, and they don’t rot the way wood does. Although carbon fiber composites are, pound for pound, stronger and stiffer than any other material, they can be damaged, which can create cracks and delamination (where layers of composites separate from each other), leading to failure.
How much does carbon fiber cost?
Carbon fiber (just the fiber) is available in several variations, offering a range of mechanical properties. The properties required by the composite part/structure determine the type of carbon fiber used. Because of this, the price of carbon fiber also varies, ranging from about $7/lb to several hundred dollars per pound. The most expensive, highest performing carbon fiber is most often used in aerospace and similar applications. The least expensive carbon fiber is used in things like piping, construction, and some automotive applications.
Finished carbon fiber composite parts and structures are expensive mainly because the material is expensive. In addition, fabrication methods tend to be labor-intensive, which drives up the cost. Further, in aerospace composites manufacturing, the material is cured in an industrial autoclave, which is time-consuming and expensive — and time is money.
There is a push in the industry to automate composites manufacturing, but that will drive down finished part cost only incrementally. Further, the primary benefit of automation is to bring consistency and repeatability to the manufacturing process.
Why is carbon fiber expensive?
The primary raw ingredient of carbon fiber (just the fiber) is called a precursor. The precursor is a polymer that is treated with extremely high heat and other processes to create carbon fiber. The highest quality carbon fiber is made with a precursor called polyacrylonitrile (PAN), which is based on the acrylic polymer. PAN is expensive because it is difficult to manufacture, plus it takes 2 lb of PAN to create 1 lb of carbon fiber. Further, the extremely high temperatures required to convert PAN to carbon fiber consumes a great deal of energy (and money). There is a lot of research right now looking at alternatives to PAN for carbon fiber precursors, and I expect that in the next 5-10 years we will see substantial progress in this effort.
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