metals and alloys

Why aluminium is used for kitchen foil

Resistant to corrosion

Why aluminium is used for cooking utensils

Resistant to corrosion, good heat conductor, high melting point

Why aluminium is used for aircraft & overhead power cables

Low density and high strength

Why copper is used for cables

Good electrical conductor; unreactive

Why zinc is used for galvanising iron

More reactive than iron

Why aluminium resists corrosion

Forms a protective oxide layer

Definition of alloy

Mixture of elements designed to have useful properties

Alloy characteristic: chemical reaction

No chemical reaction

Alloy characteristic: chemical formula

No chemical formula

Alloy characteristic: physical reaction

Just physical reaction

Alloy hardness

Alloys are harder than pure metals

Alloy conductivity

Alloys have decreased electrical conductivity

Alloy melting point

Lower melting point than pure metals

Alloy boiling point

Higher boiling point than pure metals

Brass (copper + zinc) use

Ornaments

Bronze (copper + tin) use

Ornaments

Mild steel (iron + carbon) use

Car bodies and machinery (high tensile strength)

Stainless steel (iron + nickel + chromium) use

Cutlery and surgical tools (does not rust)

High carbon steel (iron + carbon) use

Hammer and cutting tools (harder than mild steel)

Solder (tin + lead) use

Welding (low melting point)

Meaning of steel alloy

Mixture of elements that contains iron with other elements

Why high carbon steel is harder than mild steel

Particles differ more in size, reducing sliding and increasing hardness

Why alloys are harder than pure metals

Particles differ in size, reducing sliding of layers

Why alloys are preferred

Stronger/harder and resist corrosion