Exam Questions

Question 1

Which material (polymers, metals, ceramics) is ionic bonding mainly found in?

Answer 1

Polymers

Question 2

What is the fracture appearance of the surface of a ductile material?

Answer 2

Dull with voids

Question 3

What test is used to determine the ductile brittle transition temperature?*

Answer 3

Impact test

Question 4

When stress or temperature increases, what else occurs?

Answer 4

• Steady state creep rate increases
• Instantaneous strain increases
• Rupture lifetime decreases

Question 5

Which crystal structures have the same APF?

Answer 5

FCC & HCP
(74%)

Question 6

What is Poisson’s ratio?

Answer 6

A contraction perpendicular to the extension caused by a tensile stress

Question 7

How do you thermally toughen glass?

Answer 7

Creating compressive stresses in the surface layer (air jets)

Question 8

Which materials are most difficult to recycle?

Answer 8

Composites

Question 9

Isotropic Materials

Answer 9

Deformation is the same in all directions

Question 10

What is a key feature of fibres in composites?

Answer 10

High E

Question 11

What material typically has a high embodied energy?

Answer 11

Aluminium

Question 12

What is a typical sacrificial material for cathodic protection of steel?

Answer 12

Zinc or Aluminium (boat blocks)

Question 13

What happens when you increase temperature when tensile testing PE?

Answer 13

TS decreases, E decreases, YS decreases, %EL increases

(Fails later)

Question 14

Which material is an oxidizing film typical for?

Answer 14

Aluminium

Question 15

What are thermoplastics composed of?

Answer 15

Long chain-like molecules held together by weak van der Waals forces

Question 16

Why does diamond have a higher yield strength than copper wire?

Answer 16

Covalent bonds in diamond cause dislocations to be immobile

Less dislocations means higher YS

Question 17

An amorphous ceramic is heated just above the glass transition temperature. This
transition causes it to become a…

Answer 17

Supercooled liquid

Question 18

How do you determine the ductile-brittle transition temperature?

Answer 18

Using a Charpy impact test

You find the average of the max and min impact energies

Question 19

Tangent Modulus

Answer 19

Finding the gradient at a specific poitn

Question 20

Secant Modulus

Answer 20

Finding the gradient through a specific point

Question 21

Poisson’s ratio takes the ratio of what two strains?

Answer 21

Lateral / Longitudinal

Question 22

What is viscoelasticity?

Answer 22

Where a material has properties of both an ideal elastic body and viscous liquid, leading to a time dependency when returning to undeformed state

Question 23

How are relaxation and viscoelastic creep tests different?

Answer 23

Relaxation (Maxwell):
- Stress is measured against time
- Strain is held constant
- Dashpot and spring in series

Creep (Voight-Kelvin):
- Strain is measured against time
- Stress is held constant
- Dashpot and spring in parallel

Question 24

What’s the difference in oxidation and reduction?

OIL RIG

Answer 24

Oxidation is a loss of electrons and occurs at the anode.

Reduction is a gain of electrons and occurs at the cathode

Question 25

What’s the difference in oxidation and reduction?

OIL RIG

Answer 25

Oxidation is a loss of electrons and occurs at the anode.

Reduction is a gain of electrons and occurs at the cathode

Question 26

What are inhibitors?

Answer 26

Substances which decrease the environment’s corrosiveness by creating a protective layer on a metal

Question 27

What testing method is used to measure hardness?

Answer 27

Indentation

Question 28

Which hardness tests are used for measuring ferrous vs non-ferrous metals?

Answer 28

Brinell & Rockwell for ferrous metals

Vickers for non ferrous

Question 29

What is the Hall Petch observation?

Answer 29

As grain size decreases, strength of a metal increases

This makes it more difficult to move dislocations

Question 30

Galvanic Corrosion

Answer 30

Consider the Galvanic series

One becomes sacrificial other one remains the same.

Question 31

What are the 3 types of molecular structures?

Answer 31

1. Side-branched
2. Cross-linked
3. Networked