MaterialsTechnology, Xosé Rodríguez

Properties of materialsToughness: a measure of the ability of a material to withstand a shock load.

Hardness: describes the ability of a material to withstand scratching.

Strength: the ability of a material to withstand being damaged.

Elasticity: the property of certain materials that enables them to return to their original dimensions after an applied load has been removed.

Plasticity: plastic materials will remain deformed even when the load has been removed.

Conductivity: a measure of the ability of a material to conduct heat or electricity.

Plastics

1. Plastics are widely used in the home. There are many different types, some are hard, others are soft. Some are translucent, others are opaque. Propierties:

I. Very low electrical conductivityII. Low thermal conductivityIII. Low density, plastics are light.

2. There are two main groups:

I. Long chains of molecules make up thermoplastics. These can be softened with heat.

II. The molecules of thermosets interlock to form rigid materials which cannot be softened by heat.

• Thermoplastics can be INJECTION MOULDED:This machine turns granules into molten

plastic.This is injected into a hot mould where it is cooled and solidified to form the required product.

• Extrusion– Molten plastic is pushed

through a die to make long recular sections these are then cooled and solidified in a water bath.

• Vacuum forming– Plastic sheet is heated when it is soft it is

sucked onto the mould by pumping ou the air form the mould chamber.

Metals1. Propierties of metals

a. High electrical conductivity

b. High thermal conductivity

c. Though, hard and strenght.

Metals

FERROUSContain IRON

NON-FERROUSContain no IROn

Ferrous metals

Wrought iron, it has a very low carbon content.

Steel is an alloy of iron and carbone with less than 2% of carbone.

Stainless steel, also known as inox steel or inox.

Cast iron is an alloy of iron and carbone with more than 2% of carbone.

Wrought iron

Steel

A steel pylon suspending overhead powerlines.

Cast iron

Non-ferrousCopper, malleable, ductil, good

conductor of heat and electricity.

1. Bronze, alloy copper with tin.

2. Brass, alloy copper with zinc: strong and ductile Copper

Bronze

Brass

Non ferrous

• Aluminium:Light, ductile, soft,

high resistance to corrosion, silver colour

Non ferrous

• Tin–Tinplate is sheet

steel covered with a thin layer of tin.

Non-ferrous

• LeadBlue grey colour,

soft and very heavy.

I will show you an image, and then you have to say the

propierty or material related

Toughness,(fragile)

Elasticity

Strenght

Hardness

Wrought iron

Aluminium

Copper