Properties (Junior Cert Wood Technology): Revision Notes
📚 Revision Notes
Properties of Metals
Introduction
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Metals are crucial in industries such as aerospace, construction, and automotive because of their unique properties.
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Key properties are high electrical and thermal conductivity, ductility, malleability, and a shiny look. These allow diverse uses, from building materials to electronic components.
Definitions
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- Physical properties: Attributes like electrical and thermal conductivity and lustre that do not change the metal's nature.
- Mechanical properties: Characteristics about how metals act under force, like ductility and malleability, determining how they can be shaped and used.
- Electrical conductivity: Ability of metals like copper to efficiently carry electrical current, ideal for wiring.
- Thermal conductivity: Ability to transfer heat, crucial for use in heat exchangers and cooking tools.
- Ductility: Ability to be drawn into thin wires, necessary for electrical cables.
- Malleability: Ability to deform under pressure, forming sheets for automotive and aerospace uses.
- Lustre: Reflects a shiny surface, boosting visual appeal in decorative items.
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- Ferrous metals: Contain iron, often strong and magnetic but rust easily, e.g., steel.
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- Non-ferrous metals: Lack iron, usually resistant to corrosion, e.g., aluminium and copper.
Physical and Mechanical Properties of Metals
- Aluminium and copper are chosen based on traits like ductility and malleability.
- Industry Applications:
- Copper: Used in wiring for its electrical conductivity.
- Aluminium: Chosen in aerospace for its lightweight and formable nature.
Expansion and Density of Metals
- Expansion when heated: Metals like aluminium enlarge, affecting design in temperature-sensitive spots like space.
- Density: Light metals like aluminium are preferred in transport to boost fuel efficiency and performance.
Ferrous vs. Non-ferrous Metals
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- Ferrous Metals: Include iron, strong but may rust; used in durable structures.
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- Non-ferrous Metals: Include aluminium and copper, rust-resistant, fit for electrical and open-air uses.
Summary
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- Key physical traits: Electrical/thermal conductivity, ductility, malleability, and lustre.
- Mechanical features decide metal shaping and industry usage.
- Expansion and density guide metal choice for transport and building.
- Ferrous metals have iron, strong but rust-prone; non-ferrous are rust-resistant and have no iron.