Exam Style Questions: Composites, Smart Materials and Modern Materials

Question 1

Define the term composite (2 marks)

Answer 1

A combination of two or more materials that are bonded together (1) to give
properties superior to those of the individual constitutes (1)

Question 2

Name two composite materials commonly used in architecture (2 marks)

Answer 2

Award 1 mark for a correct answer up to a maximum of 2 marks

• Reinforced concrete
• Aluminium composite board
• Fibre cement
• Engineered wood
• Concrete

Question 3

This question is about carbon fibre reinforced plastic (CFRP).

a) State how epoxy resin used in the production of CFRP (1 mark)

b) Luggage is a common application for CFRP. Explain one reason why CFRP
is a suitable material for use in suitcases (2 marks)

Answer 3

a) Epoxy resin is used to hold the carbon fibre layers together/in place

b)
Award 1 mark for a relevant point and a further 1 mark for a relevant explanation
up to a maximum of 2 marks.

• CFRP is lightweight (1), weight reduction is important to maximise what passengers
  can take on holiday / airline weight restrictions (1).
• CFRP is hard wearing / tough (1), people fly frequently so luggage is subjected to
  more wear and tear (1).
• CFRP is expensive (1), higher disposable income of those who are frequent flyers,
  they can afford to spend more on their suitcase.

Question 4

This question is about tungsten carbide.

a) Tungsten carbide is a cermet. Explain what this term means (2 marks)

(b) 	Explain two ways in which tungsten carbide improves the performance of 
cutting tools (4 marks)

Answer 4

a) A cermet is a composite (1) made from ceramic and metal (1)

b)
Award 1 mark for correct property and a further 1 mark for a relevant
explanation up to a maximum of 4 marks.

• Hard (1) so will outlast other materials / will stay sharper for longer (1).
• Rigid (1) which makes efficient use of energy / makes the tool more accurate (1).
• Impact resistant/tough (1) so less likely to shatter (1).
• Stable at extreme temperatures (1) will retain properties during cutting when
  friction produces heat (1).

Question 5

Evaluate the physical and mechanical properties of concrete and concrete-based composites (6 marks)

Answer 5

Concrete:
- Can be cast into moulds to create complex vertical and/or horizontal
structures
- Durable for long-lasting structures
- High compressive strength
- Not weakened by moisture unlike timbers or metals which will degrade
more quickly in moist conditions
- Resistant to mould or pests so will endure over time
- Low maintenance, reducing costs over the lifetime of the structure
- Fire resistant so safe material for residential and commercial properties
- Can be polished to create an industrial look
- Concrete walls/floors slow the passage of heat, reducing energy
consumption needed for heating or air conditioning

Concrete-based composites:
- Reference to reinforced concrete
- Taller/larger structures possible due to steel reinforcement
- More resistant to shear stress, torsion, and tensile pressure
- Can withstand extreme weather and reduces the risk of collapse in a
natural disaster
- Steel reinforcements expand and contract at the same rate as concrete, so
the material will not fracture or crack in extreme temperatures

Question 6

Define the term smart material (2 marks)

Answer 6

A material which reacts to a given stimuli (1) and returns to its original form once
the stimuli is removed (1).

Question 7

Give two environmental factors which could stimulate a smart material (2 marks)

Answer 7

Award 1 mark for each correct response up to a maximum of 2 marks.

• Temperature / heat
• Pressure / force
• Light / UV
• Moisture
• Electrical charge

Question 8

This question is about phosphorescent pigment.

(a) Describe how phosphorescent pigment works (2 marks)
(b) Name two suitable applications for phosphorescent pigment (2 marks)

Answer 8

a) It absorbs / stores (natural and artificial) light (1) and emits light in the dark (1)

b)
Award 1 mark for each suitable application up to a maximum of 2 marks.

Stickers, nightlights, cycling accessories, camping equipment, watch/clock faces, signage

Question 9

Shape Memory Alloys (SMA) can be deformed and will return to a pre-set shape in certain conditions.

(a) Name a SMA (1 mark)

(b)	Explain two ways in which SMA’s are suitable for use in high 
performance eyewear (4 marks)

Answer 9

a) Nitinol

b)
Award 1 mark for each correct response and a further 1 mark for a relevant explanation up to a maximum of 4 marks.

• Spectacles have thin frames which are subjected to a lot of wear and tear (1) i.e. users may sit on them, put them in bags, and use them daily, use of SMAs means they can be easily returned to their original shape if they become deformed (1).
• High performance products are sold at high process (1), use of SMAs in such products is commercially viable (1).
• Spectacles are bespoke / made to a prescription (1), bespoke products attract a high price so SMAs are commercially viable (1).

Question 10

Evaluate the ways in which smart materials can be used to increase safety in 
everyday life (6 marks)

Answer 10

• Thermochromic materials can show a visual indicator of heat to prevent burning/scalding e.g. mugs, baby spoons, kettles, etc.
• Thermochromic thermometers are used to monitor body temperature; used to monitor a fever safely and easily at home
• SMAs are used in valves in taps to prevent water flowing when it is too hot, preventing scalds/burns
• Phosphorescent materials are used in safety and exit signs to show emergency
  exit route; these will function even if the electrical supply fails
• Photochromic pigment can be used in spectacles/windscreens to prevent glare/eye damage from the sun; however, the time the material takes to react to the change in light can be problematic
• Piezo electric materials are used in burglar alarms/car alarms and pressure pads
  to indicate the presence of an intruder, can easily be set off by accident
• Piezo electric materials are used to create the alarm sound in fire alarms which alerts users to evacuate the area

Question 11

The Bradley Fighting Vehicle incorporates Kevlar into the armour on the vehicle. What makes Kevlar suitable for use in this kind of vehicle? (4 marks)

Answer 11

• Kevlar is used on armoured vehicles, because it is lightweight and withstands attack from heavy duty missiles.
• The Kevlar panels protect personnel inside the vehicle.
• Kevlar is ideal because it is lightweight, and non-flammable and it offers protection from high temperatures like fire bombs.
• Can withstand the harsh environmental conditions, found in hot climates. It is a high cost piece of equipment and the added cost and performance is justified.

Question 12

Define the term modern material (2 marks)

Answer 12

A modern material has been generated through research and development
(1) to fulfil a given function (1).

Question 13

What does PMC stand for? (1 mark)

Answer 13

Precious metal clay

Question 14

Other than mouth guards, name one suitable application for polymorph (1 mark)

Answer 14

• Modelling material
• Personalised grips for utensils
• Personalised handles
• Repairs

Question 15

Describe one advantage of using Kevlar in boat hulls (2 marks)

Answer 15

Award 1 mark for a relevant point and a further 1 mark for a relevant justification up to a maximum of 2 marks.

• Stronger/tougher (1) so the boat will withstand greater impact (1) require less material (1) last longer (1)
• Boat will be lightweight (1) so it will be faster/more efficient (1) and will reduce fuel consumption (1)

Question 16

HDMF can be used to make vacuum forming moulds. Explain one

disadvantages of using HDMF for this purpose (2 marks)

Answer 16

Award 1 mark for a relevant point and a further 1 mark for each relevant justification up to a maximum of 2 marks.

• Must be painted/sealed (1) prior to prevent the mould sticking to the (1)
• HDMF is not hardwearing (1) surface of mould can be easily dented/damaged (1)

Question 17

Evaluate the use of HDMF as a material to make high-quality prototypes (6 marks)

Answer 17

• Create a tangible prototype to show product concept to target market
• Lightweight so easy to handle, however, the weight of the material/product should be considered when showing prototypes to target market
• Model/material can be manipulated easily by hand
• Compatible with CAD/CAM, can be shaped using CNC miller/router
• Can be painted and finished to make it look like another material/a finished product
• Easy to manipulate and glue by hand
• Can be milled/routed precisely and at high speed
• Fairly inexpensive material
• Lightweight so easy to handle
• High quality surface detail is possible
• Paints / fillers / adhesives with a high solvent content will dissolve the material
• Achieving a high-quality paint finish can be time-consuming

Question 18

Kevlar is widely used as protective body armour. Police dogs can also be protected
with bullet proof vests. State three properties of Kevlar and explain what makes them suitable for these applications (6 marks)

Answer 18

Award 1 mark for a correct property and a further 1 mark for a relevant explanation up to a maximum of 6 marks.

• Lightweight (1), which allows for freedom of movement (1)
• Flexible (1), so it is easy to form around the contours of the body (1)
• Impact resistant (1), able to absorb the force of a bullet (1)