Carbon fiber, 30 years ago it was considered a space age material that was far too expensive to be used in anything other than aerospace engineering, and today we encounter it in some of the most mundane objects that we can get our hands on.
Because of its strength, light weight and overall resistance, it is the material of choice for components that will have to endure a lot of physical stress or pressure, such as frames and skeletons, more or less becoming a staple of high performance sports that require any and all forms of machinery, such as cycling, motor racing, and so on.
It is also starting to become a part of the medical field, with more and more utensils being made out of carbon fiber, as well as a variety of machines being switched to this material in order to save up space and provide added resistance.
Manufacturing carbon fiber, on the other hand, is not an easy thing to do, and seeing as a single fiber is a lot thinner, yet a lot stronger, than a human hair, it is easy to see why it is so light weight and strong at the same time, as well as why it is still so expensive today.
Also known as PAN or Creslan 61, this polymer is pretty much the main ingredient in carbon fiber, making up roughly 90% of the entire composition, the remaining 10% consisting of either petroleum or rayon, depending on the type of carbon fiber that you wish to obtain.
These molecules are mixed together with different gasses and bound with carbon atoms in order to give them the strength and composure that they need. The exact proportions and ratios are actually heavily guarded secrets by the different companies that manufacture carbon fiber, the recipe varying heavily between them.
After the Pan is mixed with the various gasses and either rayon or petroleum, the end result is reacted with a catalyst producing a polyacrylonitrile plastic which is then spun into fibers using a variety of chemicals and chemical baths.
The plastic then solidifies into fibers, similar to textile fibers, which are then spun together in order to form a weave.
There are multiple ways of spinning these fibers, the most popular of them being wet spinning, where the fibers are spun within the chemical baths as they are formed.
By this point, the fibers are spun together, but they are still unstable. They chemical composition is linear at an atomic level, and before the plastic is carbonized in order to turn it into carbon fiber, it needs to be stabilized.
This is done by simply cooking the plastic in heated air at 200 – 300 degrees Celsius (390 – 590 degrees Fahrenheit) for between 30 and 120 minutes, depending on the quantity and the composition of the plastic that you are thermally treating.
There is a series of chemical reactions that take place during the stabilizing of the fibers, and each and every one of these reactions give out heat drastically altering the temperature at which they are treated, so it needs to be adjusted frequently.
After the fibers have been stabilized, they are put into a special pressurized furnace where they are heated at 1000 – 3000 degrees Celsius (1830 – 5500 degrees Fahrenheit) with absolutely no oxygen in the mix.
The lack of oxygen prevents the fibers from burning in the intense heat and because the furnace is pressurized at a pressure slightly higher than the outside pressure, the non-carbon elements burn away leaving only the carbon crystals and molecules which form a tight bond, thus creating the actual carbon fibers themselves.
It’s worth noting here that the usual safer practice is to use 2 furnaces together in order to better regulate both the temperatures and the pressure involved in this process.
At this point you have carbon fibers, however they are not in any shape or form ready for usage.
Because of their surface and texture, they cannot interact with epoxies and the other materials used in composites and thus are more or less useless.
In order to make them interact with these substances, they need to have their surfaces treated, a process known as oxidation.
The surfaces of the fibers are just slightly oxidized with oxygen atoms which are spread in such a way that they will allow the fibers to react and bond with the different substances and composites that they will come into contact with.
This process can be achieved in various ways such as immersing the fibers in various gasses, coating them electrolytically, and so on.
One very important note here is that the process is very delicate and must be done in a controlled environment to prevent the fibers from developing defects.
After all these have been said and done, you are left with the actual carbon fibers, which are of no use on their own.
They are far too small and far too thin to be used individually, which is why they are often used in weaves, more or less like textile fibers in fabrics.
This is called sizing, and it involves the fibers being treated one last time by being coated with a chemical solutions which protects them from damage that might take place while the process takes place.
The fibers are coated with adhesive and bond together in order to forma weave, more or less like you would see in a basket, and then spun on a metal cylinder called “bobbins”.
The bobbins are then loaded into special machines which spin the fibers together, twisting them into yarns of various sizes.
Unlike 30 years ago, carbon fiber is a lot cheaper and accessible, meaning that more and more fields are taking advantage of its enormous tensile strength and incredibly light weight.
Carbon fiber is user predominantly in the military, aviation and automobile industry, however they can be found in a lot of different places.
They have environmental applications as well in the form of filters and purifiers, they can be used in the medical field in various ways, especially in radiology and radio diagnostics, and they are also found often in sporting goods like bicycle frames, gold clubs, canoe paddles, skis, and so on.
Because of the potential and at the same time incredibly reduced impact that carbon fiber has on the environment, there have been multiple projects announced for the following 3 years which involve heavy usage of carbon fiber.
These projects range from oil exploration to alternate energy, construction and infrastructure, replacing inferior materials that required heavy usage of resources and had very limited life spans.
It is estimated that by 2020, carbon fiber will replace a large amount of these materials, and with proper development and research there might be instances where carbon fiber replaces all the elements in certain objects and components.