Carbon Fibre
What is Carbon Fibre?
Carbon fibre is a high‑performance composite material made from extremely thin strands of carbon atoms. These fibres are woven into a fabric and combined with a polymer resin (usually epoxy) to form carbon fibre reinforced polymer (CFRP).
Carbon fibre is widely used in applications where high strength, stiffness, and low weight are required.
Structure and Composition
Carbon fibre is a composite material, meaning it consists of two main components:
- Reinforcement: Carbon fibres that provide strength and stiffness
- Matrix: A polymer resin that holds the fibres together and transfers loads
The fibres are typically 5–10 micrometres in diameter. Carbon atoms are aligned in long crystal structures, which gives the material its exceptional tensile strength.
Manufacturing Process
Fibre Production
- Usually produced from polyacrylonitrile (PAN)
- Heated to extremely high temperatures in an oxygen‑free environment
- This process is known as carbonisation
Weaving
- Fibres are woven into sheets (e.g. plain weave or twill weave)
Lay‑Up
- Layers of fibre are placed into a mould
- Resin is applied using:
- Wet lay‑up
- Pre‑preg materials
Curing
- Heat and pressure are applied using:
- Autoclaves
- Ovens
- Vacuum bagging
Key Properties
| Property | Description |
|---|---|
| Strength | Very high tensile strength |
| Weight | Extremely lightweight |
| Stiffness | Very rigid |
| Corrosion Resistance | Does not rust |
| Thermal Resistance | Stable at high temperatures |
| Electrical Conductivity | Conducts electricity |
Advantages
- Very high strength‑to‑weight ratio
- Excellent stiffness and rigidity
- Resistant to corrosion and fatigue
- High‑quality surface finish
- Long service life
Disadvantages
- Very expensive material
- Complex and energy‑intensive manufacturing
- Difficult to recycle
- Brittle under impact
- Requires specialist skills and equipment
Typical Uses
Carbon fibre is used in high‑performance and specialist products, including:
- Aerospace – aircraft structures
- Automotive – supercars and Formula 1
- Sports Equipment – bicycles, rackets, helmets
- Medical – prosthetics and imaging equipment
- Product Design – high‑end consumer products
Sustainability and Environmental Impact
Advantages
- Lightweight products reduce fuel consumption
- Long lifespan reduces the need for replacement
Disadvantages
- High energy use during production
- Thermoset resins are difficult to recycle
Developments
- Recyclable resins
- Reuse of carbon fibre waste
- Bio‑based polymers
Health and Safety Considerations
- Carbon fibre dust can irritate lungs and skin
- PPE required:
- Gloves
- Eye protection
- Dust masks
- Dust extraction should be used when cutting or sanding
Carbon Fibre Compared to Other Materials
| Material | Strength | Weight | Cost |
|---|---|---|---|
| Carbon Fibre | Very High | Very Low | Very High |
| Aluminium | Medium | Low | Medium |
| Steel | High | High | Low |
| Glass Fibre | Medium | Medium | Low |
Suitability for Product Design
Carbon fibre is suitable when: - Weight reduction is critical - High performance is required - Cost is not a limiting factor
It is not suitable for: - Mass‑produced products - Low‑cost designs - Simple school workshop manufacture
Exam Tips (A Level)
- State that carbon fibre is a composite material
- Mention reinforcement and matrix
- Refer to strength‑to‑weight ratio
- Consider cost and sustainability
- Link material choice to function and user needs
Key Keywords
- Composite material
- Reinforcement
- Matrix
- Epoxy resin
- Autoclave
- Pre‑preg
- Tensile strength
- Carbonisation
Overall Summary
Carbon fibre is a high‑performance composite material made from carbon fibres and a polymer resin. It offers an excellent strength‑to‑weight ratio, high stiffness, and resistance to corrosion, making it ideal for aerospace, automotive, sports, and high‑end product design applications. However, its high cost, complex manufacturing, and environmental impact limit its use to specialist products. In A Level Product Design, carbon fibre is best discussed in terms of material structure, properties, manufacturing methods, and suitability for specific design contexts.