Properties of Materials

Unit 4 – Materials

Technologies 1st ESO – IES Poeta Julián AndúgarAntonio Ruiz Hernández

Material Properties

How can we choose what material should we use? Physical Properties Chemical Properties Ecological Properties

Physical Properties

How they react to external stimuli? Physical Properties:

Electrical Thermal Acoustic Magnetic Optical Mechanical Other properties

Electrical Properties

We can distinguish between: Electrical conductivity: metals. Electrical insulation: plastic, wood,

stone, ceramics

Thermal Properties

How do materials behave when heated? Thermal conductors: metals Thermal insulators: wood and plastic Fusibility: Metals, some plastics and

glass. Welding: Metals, e.g. Tin.

Thermal Properties

Thermal Properties

Thermal Properties

Acoustic Properties

Can you hear sound through a material? Acoustic conductors. Acoustic insulators: glass, cork &

plastics

Magnetic Properties

Does a magnet attract the material? Magnetism: Ferrous metals (steel).

Optical Properties

Can you see light through a material? Opaque: Light don’t pass. Wood &

Metals. Translucent: Light passes, but we

cannot see objects behind them clearly. Some types of glass and plastic.

Transparent: We can see perfectly through them: Glass and some plastics.

Optical Properties

Opaque

TranslucentTransparent

Mechanical Properties

Mechanical Strength. How the material resists the action of forces.

Elasticity. The material returns to its original form after a force that has changed its shape is removed.

Plasticity. The material is permanently deformed after a force is applied.

Malleability: Allows a material to be spread into sheets or films.

Ductility: Allows a material to be formed into filaments or wires

Other Physical Properties

Density. Relation between mass of an object and its volume.

Permeability: Allows water or other liquids to filter through them.

Impermeability: Doesn’t allow water or other liquids to filter through them.

Chemical Properties

When the chemical composition of a material changes because it interacts with other substances.

Oxidation. The material reacts with the oxygen in the air or water. This happens with metals, producing rust.

Ecological Properties

Recyclable materials. They can be reused (Glass, paper, cardboard, metal, plastics).

Toxic materials. Harmful and sometimes poisonous (Mercury, heavy metals, petroleum).

Biodegradable materials. They decompose naturally and don’t damage the environment (paper, bioplastics,…)

Thank you very much

for your attention!