Metals

Question 1

What is alloy?

Answer 1

• a metal combined with other materials
• the properties of the metal are changed
• different combinations are created to suit particular purposes and needs

Question 2

What is Ferrous metals?

Answer 2

metals that contain iron

Question 3

What is Non-ferrous metals?

Answer 3

metals that do not contain iron

Question 4

What is ferric oxide (rust)

Answer 4

• the reddish-brown substance found on ferrous metals

- formed when metals containing iron come into contact with oxygen in the presence of water

Question 5

What is another name for ferric oxide?

Answer 5

Rust

Question 6

What is oxidation

Answer 6

-a chemical reaction in which a substance combines with oxygen or loses hydrogen or electrons

Question 7

What is galvanising

Answer 7

-the term used when protective layer of zinc is applied to the iron or steel to prevent it from rusting

Question 8

What is electroplating

Answer 8

-a method of galvanising in which a coating of zinc is applied to a metal by electrolysis

Question 9

What is electrolysis

Answer 9

-a method of splitting the elements in a compound by passing an electric current through the compound when it is a solution

Question 10

What is a electrolyte

Answer 10

-a solution that can conduct an electric current

Question 11

What does paint form

Answer 11

-a barrier between air and inner metal

Question 12

how to prepare the metal for painting

Answer 12

1- clean surface, remove all grease and grime washing it in hot water with highly concentrated cleaning agent
2-work in dust free zone
3-thre coats primer, under coat and topcoat
4-prmer has very strong bond with metal and undercoat
5-undercoat so that it will stick to the primer, helps to be waterproof
6-top coat provides resistance to ultraviolet light and weathering, gives it a desired finish
7- paint awkward places first
8-two thin coats of topcoat are better than one coat

Question 13

What is the first method of galvanising

Answer 13

-is to immerse the iron or steel in a liquid zinc bath at 460C
called hot-dip

Question 14

What does hot dip produce

Answer 14

• a this,durable, dull grey coating makes it possible for outdoors

Question 15

What is the second method of galvanising

Answer 15

• by electroplating
• where an electric current is passed through an electrolyte
• it is a process that conducts electricity because it has a positive and negative charges

Question 16

What does electroplating produce

Answer 16

• thin coating that reflects brightly in the same way asa mirror
• for indoors

Question 17

what happens when iron and steel have been galvanised

Answer 17

• they will resist corrosion

even through exposed air and moisture