What is Carbon Fiber?

Real Carbon Inc.

Carbon fiber is often described as the “dream material” of modern engineering. Known for its incredible strength-to-weight ratio, it has revolutionized industries ranging from aerospace and Formula 1 racing to high-end sports equipment and civil engineering. While it looks like a simple black fabric or a rigid plastic, it is actually a highly sophisticated material composed of organized carbon atoms. So;

What is Carbon Fiber?

At its core, carbon fiber is a long, thin strand of material about 5 to 10 micrometers in diameter—significantly thinner than a human hair. It is composed mostly of carbon atoms bonded together in microscopic crystals that are more or less aligned parallel to the long axis of the fiber.

The primary appeal of carbon fiber lies in its physical properties:

• High Tensile Strength: It is one of the strongest materials available for its weight.

• High Stiffness: It has a high modulus of elasticity, meaning it does not stretch or bend easily under load.

• Low Weight: It is roughly five times stronger than steel and twice as stiff, yet weighs about two-thirds less.

• Chemical Resistance: It is highly resistant to corrosion and chemical reactions.

• Low Thermal Expansion: It does not expand or contract significantly with temperature changes, making it ideal for precision instruments.

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How is Carbon Fiber Made?

The production of carbon fiber is a complex chemical and mechanical process. It isn’t “grown” or “mined”; rather, it is converted from a precursor material through intense heat and chemical stabilization. About 90% of carbon fiber is made from Polyacrylonitrile (PAN), while the remaining 10% is made from rayon or petroleum pitch.

The manufacturing process can be broken down into five distinct stages:

1. Spinning

The process begins with the precursor (usually PAN). The PAN plastic is mixed with other ingredients and spun into long fibers. These fibers are then washed and stretched to align the molecules within the polymer. This alignment is crucial because it sets the foundation for the strength of the final carbon fiber.

2. Stabilizing (Oxidation)

Before the fibers can be carbonized, they must be chemically altered to prevent them from melting at high temperatures. The fibers are heated in air to approximately 200°C–300°C for 30 to 120 minutes.

• This causes the fibers to pick up oxygen molecules from the air and rearrange their atomic bonding pattern.

• The fiber changes color from white to brown or black during this stage.

3. Carbonizing

This is the most critical stage. The stabilized fibers are heated in a furnace filled with a gas mixture that contains no oxygen (usually nitrogen). Because there is no oxygen, the fibers cannot burn. Instead, the intense heat—ranging from 1,000°C to 3,000°C—causes the non-carbon atoms (oxygen, nitrogen, and hydrogen) to vibrate and break away.

• What remains is a chain of tightly interlocked carbon atoms.

• The higher the temperature used during this phase, the higher the “modulus” (stiffness) of the resulting fiber.

4. Surface Treatment

After carbonization, the surface of the fibers does not bond well with epoxies or resins used in manufacturing. To fix this, the surface is slightly oxidized. Adding oxygen atoms to the surface provides better chemical bonding properties and creates a “roughed up” surface for better mechanical interlocking.

5. Sizing

The final step is coating the fibers with a protective material, such as epoxy, polyester, or nylon. This is called sizing. It protects the delicate fibers from damage during winding or weaving and ensures compatibility with the resin that will eventually turn the fibers into a composite part.

 

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From Fiber to Composite: The “Matrix”

Carbon fiber is rarely used on its own. To create a structural part, the fibers must be combined with a polymer resin (the matrix). This combination is known as a Carbon Fiber Reinforced Polymer (CFRP).

Think of it like reinforced concrete: the carbon fibers provide the tensile strength (like the steel rebar), while the resin provides the shape and compressive strength (like the concrete).

Common Forms of Carbon Fiber:

• Tow: A bundle of thousands of individual carbon filaments (e.g., “3k” means 3,000 filaments per bundle).

• Weave: The tows are woven into fabrics with various patterns (plain, twill, or satin), which gives carbon fiber its iconic “checkered” look.

• Pre-preg: Fabric that has been pre-impregnated with resin and stored in a freezer. This allows for high-precision manufacturing in aerospace. At Real Carbon 99% of our products are made using this form of Carbon Fiber.

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Applications and Future

Because of its high cost, carbon fiber was once reserved for military aircraft and space exploration. However, as manufacturing techniques improve, it is becoming more common.

Industry	Usage
Aerospace	Wings and fuselages for the Boeing 787 and Airbus A350 to save fuel.
Automotive	Chassis for supercars and high-end EVs like the BMW i3 or Porsche 911 variants.
Sports	Tennis rackets, golf clubs, high-end bicycles, and racing helmets.
Energy	Massive turbine blades for wind energy that need to be light yet stiff.

The Challenges

The primary drawback of carbon fiber is cost and recyclability. At Real Carbon we have been working on recycling our carbon fiber pre-preg to make strong, lightweight products. Unlike steel or aluminum, which can be melted down and reused easily, carbon fiber composites are difficult to break down once the resin has cured. Research is currently focused on “thermoplastic” resins that could allow carbon fiber parts to be recycled more effectively in the future.

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Carbon fiber represents the pinnacle of material science—a perfect marriage of chemistry and physics that allows us to build faster, lighter, and stronger than ever before.

Mike Graham