Basics of Carbon Fiber - What You Should Know

Mar 31 / Gavin Wride

What is Carbon Fiber?

Carbon fiber is something you’ve maybe heard about being vaguely connected to the aerospace industry. Or maybe you’ve seen parts of a vehicle and the owner brags how “This is actually made of carbon fiber.” Maybe you already know a bit more than that, or maybe you know the words carbon and fiber separately, but never together. Basically, if you haven’t heard much about carbon fiber, you’ve at least probably gathered from the tone of voice people use when speaking about it, it’s impressive and expensive.

The material is a product of an industry known as composite manufacturing. Composite manufacturing is the combination of two or more materials that have new properties that wouldn’t be there without the union.

Carbon fiber is a manufactured composite made from strings of carbon that are woven into yarn and then further into sheets, tubes, or almost any other desired shape. Along with its malleability, carbon fiber is often chosen for its high strength to weight properties and high temperature resistance.

How is it Made?

Because of the amount of money to be made in the market, the methods for creating carbon fiber can vary drastically from company to company. Because different chemicals can add different properties to the composite, carbon fiber manufacturers keep their process as a trade secret.

That being said, there are basics to carbon fiber production that most businesses will follow. All carbon fiber is made from “precursors” which are the raw materials that transition into the fiber after multiple processes. The most popular precursor (used in about 90% of all carbon fiber) is polyacrylonitrile (PAN). PAN is a thermoplastic with a high melting point and oxidation point that suits carbon fiber production well. If PAN is not used as a precursor, rayon or petroleum pitch are likely the next best options.

Whether it’s PAN, rayon, or petroleum pitch, the precursor is used because they are organic polymers. These polymers’ molecules form long strands, bound by carbon atoms. The overall process of formation capitalizes on the molecular structure of these precursors by weaving the strings together in a tight knit fashion that augments the strength of the material manifold.
Before any weaving can begin, however, certain chemical processes must take place to cure the precursor. The first chemical process involves removing as many non-carbon atoms from the material. The way this is done is through placing the precursor in an anaerobic zone with extremely high temperatures. Because of the lack of oxygen, the fiber itself won’t burn.

Rather, with the high temperature, the non-carbon atoms vibrate to such an extent that they’re expelled from the strands. The act of removing almost everything except for the carbon is called carbonization, and this process is used in carbon fiber to strengthen the overall material. By keeping everything carbon, the carbon strands can interlock tighter and produce a better fiber in the long run.

After carbonization, the fibers are almost ready, but without oxygen, none of the binding agents and epoxies would be able to coat the material in order to shape it and get other chemical and physical properties from the material. Bringing oxygen into carbon fiber⁠–or anything else⁠–is a process called oxidation.

This process can be achieved in various ways and can differ depending on the producer, but it’s often performed by immersing the fibers in gasses such as air, carbon dioxide, or ozone. The interaction between the nearly pure carbon and the chosen gas will oxidize the material. Another common method is to soak the material in various liquids such as sodium hypochlorite or nitric acid.

After the oxidation process, another process takes place. ‘Sizing’ involves coating the fibers to protect against any damage that would come during winding or weaving. Companies employ this process in a variety of ways, but the coating materials are selected based on the selected precursor and the desired results. Some common materials for coating the fibers include polyester, epoxy, nylon, urethane, and others.

Once the fibers have been sized, the next step is to weave them into yarns of different sizes and lengths. To do so, the material is wound onto cylinders called bobbins. Yarn and thread for sewing are also wound around bobbins. The ones for carbon fiber are larger than thread bobbins, but they function almost exactly the same.

Spinning machines use multiple bobbins to weave the yarns. Production plants weave carbon fiber in different patterns according to the use of the material. Most often, the weaving will end up with an enormous sheet of carbon fiber that is then cut and used in whatever end product needs it.

History of Carbon Fiber

Carbon fiber, while thought of as a relatively new product and technology has been around for over a decade and a half. Only recently, however, has the material received global attention and production.

At its conception, carbon fiber looked quite different and had an entirely different purpose in mind. Sir Joseph Wilson Swan is the first recorded person to create carbon fiber. He made the material in order to create incandescent light bulbs.

Thomas Edison continued the use of carbon fiber for light bulb filaments in 1879. This material was chosen as an ideal electric conductor because of its high heat tolerance and malleability. Edison and Swan made this material in a drastically different fashion than we see in modern times. Most often the filaments would be constructed out of bamboo or cotton. Once the shape was found, they would bake the material at high temperatures to cause carbonization.
While carbon fiber creation was practiced in those early days, it quickly became obsolete once inventors discovered that tungsten functions as a better filament for light bulbs. Because carbon fiber was seen to have only one function, the introduction of a better system led to its quick decline.

Not until 1958 did carbon fiber see a resurgence in production and use. Union Carbide Parma Technical Center in Ohio gave birth to another rise in carbon fiber as an accident. Roger Bacon was trying to measure the triple point of carbon by heating strands of rayon in argon when he produced the first petroleum-based carbon fiber. Because of the material used, only about one-fifth of the fibers were carbon, but the carbonization process had occurred and would be the first step towards modern carbon fiber usage.
The 1960s then became a Renaissance period for carbon fibers. Much of the research and production from this period has shaped how we make carbon fibers today. After the ‘60s, not much extreme innovation occurred, just minor changes to increase efficiency and differentiation.

Almost one hundred years after carbon fiber’s initial creation (1961), Richard Millington applied for a patent for a carbon fiber production system that would have a high carbon content. Millington’s process called for rayon as a precursor which he would then rinse and dry before he would “fire in a closed atmosphere at successively higher temperatures”. After a cool down and then quick burn, the fibers would be woven to create a high strength to weight composite material with high temperature resistance.

While Millington’s method resembles the process we use nowadays, in the early 1960s, Dr. Akio Shindo used PAN as a precursor. He used a process that resulted in about 55% carbon content, but his production was more cost-friendly than Millington’s.

Research and development of this product continued throughout the 1960s globally, though the primary players were from Japan, the US, and the UK. During this time, many companies and inventors sought out alternative raw materials that could strengthen and cheapen the end product. Petroleum pitch was developed as a precursor, which is a byproduct of oil processing. This petroleum would lead to an 85% carbon contact fiber that had impressive strength and modularity.

Advancement of the material has continued for the past few decades, leading us to the market we have today. In 2018, the United States accounted for roughly a third of the global carbon fiber production capacity. Japan followed in production, accounting for 18%, only six percent above China.

Where is Carbon Fiber Used?

Global demand for the carbon fiber market in 2012 was estimated to be around 1.7 billion dollars, with an expected steady increase. With such a high demand, the question arises, “Who uses it?” and “What is carbon fiber used for?”

Given its galvanic corrosion resistance, high strength to weight ratio, and high temperature resistance, the uses for carbon fiber are wide, varied, and still largely undiscovered. But, because it’s currently more expensive than steel and most other building materials, access to carbon fiber has stayed largely in the manufacturing industry and other specialized fields.

Carbon fiber applications include engineering, aerospace, high-performance vehicles, construction, sporting equipment, musical instruments, drone parts, safety equipment, and medical equipment. The chemical and physical properties of carbon fiber enable it to take on multiple purposes, and its light weight makes it ideal for most of these applications.

The aerospace industry uses carbon fiber for many reasons, but it’s often used to make aircraft parts and rocket parts. Even the James Webb Space Telescope took to using the material. Because of its low thermal expansion, carbon fiber was used as a backing for the device to ensure that, despite dramatic fluctuations in temperature, the highly sensitive optical parts would remain in place. Another example of carbon fiber’s importance can be seen in Boeing’s 787 dreamliner, which uses about 50% of its weight as composite materials, mostly carbon fiber.

Much of the energy field has also taken to using carbon fiber. Wind turbines use fiberglass, another composite material, but studies have shown that using carbon fiber lowers the mass reduction of the blades by about 25%. This means that for the same weight (and a much easier upkeep) carbon fiber could lengthen the blades and capture more energy in low wind circumstances. The field of energy also uses carbon fiber in natural gas storage and fuel cells for energy transportation.

Basically, carbon fiber has improved almost every industry it’s touched. People on the cutting edge of innovation continue to explore the material’s potential as the cost of production continues to move down. There could come a time when we don’t just see carbon fiber being used as airplanes but also with things so common and prevalent as clothing.

Want to Work with Carbon Fiber?

With the potential uses for carbon fiber, the market for the material has continually expanded and is estimated to keep that trajectory. Demand for the material keeps rising and for supply to keep up, companies need plenty of workers.

Something recent in the field of technology, however, has slowed that potential. With technological advancements always on the rise, people and traditional education methods have struggled to keep up, lowering the amount of workers who are prepared and able to take jobs in fields such as carbon fiber production.

This space between what’s available and what’s needed has caused some disillusionment and pain for many people. Because of the speed of technological advancements, an ambitious and eager mind may go through four years at a top university and still be behind industry standards.

This pain and confusion has led to Open X stepping up to the plate with the goal of providing user-friendly, cost-efficient training that allow the user to quickly learn the skills they need to begin their careers in tech. We have taken a scientific approach to learning and teaching that enables the learner to take things at their own pace, learn in a variety of ways (audio, visual, tactile, and so on), and explore a variety of options before spending valuable time and money on obtaining a career.

We've given the option for a free trial of our services, with access to many different courses including carbon fiber. Our platform will help you learn the skills you need to make your own carbon fiber parts and to secure an entry-level position as a Composite Carbon Fiber Technician.

The free trial will let you see if our methods of teaching are right for you, and our courses will let you explore many different options in order to find your passion without breaking the bank. We also want to help you take those steps towards a career and will use our network to connect you with those groups that need you most.

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