Composites

 

What are composites?

Composite materials consist of two or more different kinds of material.

The materials for a composite material are chosen because they have different properties that work together to make a more useful material. The properties of each material in the composite are described as enhancing each other.

 

Examples of composites:

 

• Breathable fabrics: Breathable fabrics are composite materials that combine the advantages of nylon (durable, light, and waterproof) and breathability. They prevent rain from entering while allowing sweat to evaporate to the outside.
• Carbon fibre reinforced polymer (CFRP): Carbon fibre reinforced polymer (CFRP) is made from carbon fibre that is strong and light but very flexible, and a polymer resin that is stiff but weak. CFRP is rigid, strong and light which makes it perfect for designing advanced racing bike frames.
• Fibreglass: Fibreglass is made from a network of glass fibres embedded in a tough polymer. The glass fibres make the material strong, the polymer makes it lightweight. These properties make it useful for making these kayaks that have to float and could be hit by rocks when travelling down a river.
• Reinforced concrete: Reinforced concrete is a composite material. It is made by pouring concrete around a mesh of steel cables. When the concrete hardens, the material is strong when stretched (because of the steel) and strong when compressed (because of the concrete).
• Medium density fibreboard (MDF): MDF is made from wood fibres and glue. It is easy to shape, flexible and can be painted and glued easily. It can be made into different thicknesses. This makes it useful for making furniture.

 

🧪 Knowledge Check: Composite Materials

Test your understanding of how composites are made and their common uses.

1. In a composite material, what is the 'matrix'?

• The thin fibres that provide strength.
• The material that surrounds and binds the reinforcement.
• The tool used to mix the materials.

2. Why are two or more materials combined to make a composite?

• To create a material with improved properties.
• To make the material change colour easily.
• To make the material easier to dissolve in water.

3. Which composite is made from thin layers of wood glued together?

• Carbon fibre
• Glass-reinforced plastic (GRP)
• Plywood

4. Reinforced concrete is a composite made from which two materials?

• Steel rods and concrete
• Glass fibres and plastic
• Carbon fibres and wood

5. Which property makes carbon fibre useful for high-performance cars and bikes?

• It is very heavy and stiff.
• It is lightweight and extremely strong.
• It is soft and flexible.

Click to Reveal Answers

1. The material that surrounds and binds the reinforcement (It holds the structure together).
2. To create a material with improved properties (Combining them takes the best traits of each).
3. Plywood (Alternating layers of wood grain make it stronger).
4. Steel rods and concrete (The steel provides tension strength while the concrete provides compression strength).
5. Lightweight and extremely strong (Ideal for speed and durability).

 

Summary:

 

• Composite materials consist of two or more different kinds of material.
• Composite materials are artificial and are made by a chemical process.
• Composite materials are designed for specific uses.