UNIT 4_ Materialspart 2: Properties

Technologies 1 ESO

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LET’S CHECK!!If glasses were made of opaque plastic, we would not see anything.

If umbrellas were made of lace fabric, we would get wet because it’s a permeable material.

If it rained on these paper shoes, our feet would get wet because paper is a permeable material.

If keys were made of glass, they would break because glass is a fragile material.

WE CHOOSE THE MOST SUITABLE MATERIAL TO MANUFACTURE AN

OBJECT LOOKING AT ITSPROPERTIES

WHAT DID WE LEARN?

1. VISUAL PROPERTIESTRANSPARENCY

Capability of a material to let the light through and the objects clearly seen.

A material can be: Opaque, translucid or transparent

Remember the names of the properties:Opacity

TranslucidityTransparency

2. THERMAL PROPERTIESTHERMAL CONDUCTIVITY

Capability of a material to transmit the heat through it. A material can be: Thermal insulator or thermal

conductor

2. THERMAL PROPERTIES (II)FUSIBILITY

Capability of a material to melt (turn from solid to liquid) under high temperatures.

Materials: Melt at different temperatures

Materials that don’t melt, but burn, are: Combustible

3. ELECTRICAL PROPERTIESELECTRICAL CONDUCTIVITY

Capability of a material to transmit the electricity through it. An object can be: Electric insulator or electric

conductor

HAVE A DEEP LOOK AROUND YOU…

… AND FIND:

2 OPAQUE OBJECTS

2 TRANSLUCENT OBJECTS

2 TRANSPARENT OBJECTS

4. MECHANICAL PROPERTIESELASTICITY

Capability of a material to change shape under a force and then return to its original shape when we stop the force.

A material can be: Elastic or rigid

4. MECHANICAL PROPERTIES (II)PLASTICITY

Capability of a material to change shape forever and to not come back to its original shape.

An object can be: Plastic or rigid

HAVE A DEEP LOOK AROUND YOU…

… AND FIND:

2 PLASTIC OBJECTS

2 ELASTIC OBJECTS

2 RIGID OBJECTS

4. MECHANICAL PROPERTIES (III)HARDNESS

Resistance of a material to scratching, cutting or bending.An object can be: Hard or soft

4. MECHANICAL PROPERTIES (IV)TOUGHNESS and FRAGILITY

Capability of a material to deform without fracturing when we hit it.

An object can be: Tough or fragile (brittle)

HAVE A DEEP LOOK AROUND YOU…… AND FIND:

2 HARD OBJECTS

2 SOFT OBJECTS

2 TOUGH OBJECTS

2 FRAGILE OBJECTS

5. CHEMICAL PROPERTIESOXIDATION

Capability of a metal to change its composition under the presence of water or oxygen.

A metal can oxidize easily or be stainless

5. CHEMICAL PROPERTIES (II)PERMEABILITY

Capability of a material to let the water through.A material can be: Permeable or impermeable

(waterproof)

HAVE A DEEP LOOK AROUND YOU…

… AND FIND:

2 STAINLESS OBJECTS

2 WATERPROOF OBJECTS

6. MANUFACTURING PROPERTIESDUCTILITY

Capability of a material to being streched into thin wires or threads.

A material can be: Ductile or non-ductile

6. MANUFACTURING PROPERTIES (II)

MALLEABILITYCapability of a material to being hammered into thin sheets.

A material can be: Malleable or non-malleable

6. MANUFACTURING PROPERTIES (III)

WELDINGWelding is a process to join materials (metals and plastics mostly) through local fusion between two pieces.

A material can be: Weldable or non-weldable

HAVE A DEEP LOOK AROUND YOU…

… AND FIND:

2 DUCTILE MATERIALS

2 MALLEABLE MATERIALS

7. ECOLOGICAL PROPERTIESBIODEGRADABILITY

Capability of a material to being decomposed by nature (bacteria).A material can be: Biodegradable or non-biodegradable

8. ECONOMIC PROPERTIESPRICE

Amount of money given to pay for a material.A material can be: Cheap or expensive