Aluminium works due to its unique combination of properties, making it useful in various applications, primarily as a conductor of electricity and a reflector of light and heat.
Here's a breakdown of how aluminium functions in different scenarios:
1. Electrical Conductivity:
- Aluminium is an excellent electrical conductor. This is because of the freely moving electrons in its atomic structure. These electrons can easily carry an electrical charge.
- It's widely used in electrical transmission lines.
- While copper is a better conductor per unit volume, aluminium is significantly lighter. For the same weight, aluminium conducts almost twice as well as copper. This makes it more cost-effective for long-distance power transmission, where weight is a crucial factor.
- Aluminium cables often incorporate steel strands for increased tensile strength, especially in overhead power lines.
2. Reflectivity:
- When aluminium is evaporated in a vacuum, it forms a thin, highly reflective coating.
- This coating reflects both light and heat very efficiently.
- This property is used in applications such as:
- Mirrors
- Reflectors in lighting fixtures
- Thermal insulation (reflecting heat radiation)
- Protective coatings on satellites and spacecraft to regulate temperature.
- Packaging material such as aluminium foil for food, reflecting heat and light.
3. Mechanical Properties and Corrosion Resistance:
- While not as strong as steel, aluminium is strong for its weight.
- It readily forms alloys with other metals (like magnesium, silicon, and copper) to significantly improve its strength and hardness. These alloys are used in aerospace, automotive, and construction industries.
- Aluminium forms a thin, naturally occurring oxide layer (aluminium oxide) on its surface when exposed to air. This layer is very hard and resistant to corrosion, protecting the metal underneath. This self-passivating property makes aluminium suitable for outdoor applications and environments where corrosion is a concern.
Summary:
Aluminium's functionality stems from its electrical conductivity, high reflectivity when vapor-deposited, good strength-to-weight ratio (especially in alloys), and inherent corrosion resistance. These properties make it a versatile material in a wide range of applications.
