Material Properties

Question 1

What Properties does atomic structure affect?

Answer 1

Chemical
Physical
Thermal
Electrical
Magnetic
Optical

Question 2

What do micro and macroscopic structure affect?

Answer 2

Mechanical properties

Question 3

What is ionic bonding? What properties does it cause?

Answer 3

Between a metal and non-metal. Electron leaves metal and joins non-metal forming two oppositely charged ions which attract.

Hard
Insulators
Brittle
High melting point

Question 4

What is metallic bonding? What properties does it cause?

Answer 4

One or more electrons from outer shell are shared by metal atoms.

Conductors
Ductile
Opaque

Question 5

What is covalent bonding?

What properties does it cause?

Answer 5

Both non-metal atoms share a pair of electrons to form a bond.

Soft or brittle
Insulators
Low melting points

Question 6

What is the difference between amorphous and crystalline structure and which appears more often?

Answer 6

Crystalline structure shows long range and short range order in a regular repeating structure. Amorphous shows no particular structure. 90% of natural and prepared solids are crystalline.

Question 7

Describe metallic crystal structure

Answer 7

Electrons leave outer shell of metal to form positive metal ions and a sea of delocalised electrons. The ions are closely packed and arranged in a regular metallic lattice.

Question 8

Give 3 properties of amorphous metals

Answer 8

Disordered atomic structure
Glass-like structure
Good electrical conductors

Question 9

Discuss advantages and disadvantages of metal pipes

Answer 9

\+
high strength so can withstand weight/pressure
Non-porous so can transfer fluids
Easy to process into shape
Available worldwide
High thermal conductivity
Can be recycled

-
Suffer from corrosion
Particles may wear it
High thermal conductivity
May have cheaper alternatives.

Question 10

What properties do thermoplastics have and what gives them this property?
Give 3 examples of thermoplastics.

Answer 10

They can be heated and melted, then cooled and reformed.
This property is due to cross-linking.
Polyethylene, polypropylene, polyvinyl chloride, polystyrene, acrylic, nylon, teflon.

Question 11

Why can thermosets not be melted?

Give 3 examples of thermosets.

Answer 11

Because the chemical reactions that produce cross-linking form an infusible and insoluble polymer network.
Epoxy resin, melamine formaldehyde, polyester resin, urea formaldehyde.

Question 12

What two structures can ceramic be?

What bonding is present in ceramics?

Answer 12

Crystalline and semi-crystalline

Mainly ionic and covalent bonding

Question 13

What is a composite?

Answer 13

Material made from two or more constituent materials with different properties, which give unique chemical and physical properties when combined with each other.

Question 14

What are the usual two parts of a composite?

Answer 14

The matrix and the reinforcement. The matrix surrounds and binds the other fragments.

Question 15

Name 3 composites

Answer 15

Wood
Bone
Fibreglass
Carbon nanotubes
Carbon fibre

Question 16

What do mechanical properties describe?

Give 3 mechanical properties.

Answer 16

What happens to materials when they are subjected to force.
Density
Hardness
Ductility
Yield strength

Question 17

What is Barlow’s formula?

Answer 17

P = 2ST/D
P - maximum working pressure in a pipe (Pa)
S - Material strength or allowable stress (Pa)
T - Pipe wall thickness
D - Pipe outside diameter

Question 18

What is Archard’s formula?

Answer 18

Q = KWL/H
Q - Total volume of wear debris produced (m3)
K - Wear constant
W - Total normal load (N)
L - Sliding distance (m)
H - Hardness of softest contact surface (MPa)