Smart Materials

Question 1

what is a smart material?

Answer 1

a material with a property that is altered by an external stimulus

Question 2

what properties change when exposed to a stimulus? [5]

Answer 2

• colour
• shape
• viscosity
• volume
• conductivity

Question 3

what 4 factors affect smart materials?

Answer 3

• temperature changes
• levels of light
• moisture
• pressure

Question 4

examples of smart materials [6]

Answer 4

• shape memory alloys
• thermochromic pigment
• phosphorescent pigment
• photochromic pigment
• electroluminescent wire
• Piezoelectric material

Question 5

what are shape memory alloys?

Answer 5

materials programmed to remember a specific shape

Question 6

what stimuli activates SMA?

Answer 6

• weather
• body temperature
• electrical current

Question 7

what is the most common shape memory alloy?

Answer 7

Nitinol [nickel and titanium

Question 8

how do you program shape memory alloys?

Answer 8

• shaped in a jig then heated [furnace/flame/electric] above transformation temperature
• once cooled the SMA will return to its jig shape when deformed by heat
• activation temperature for reforming is dictated by materials composition

Question 9

uses for shape memory alloys

Answer 9

• glasses frames
• orthodontic braces wire
• heat sensitive valves

Question 10

what does thermochromic pigment do?

Answer 10

changes colour or opacity when a temperature change occurs

Question 11

where can thermochromic pigment be added? [not products] [6]

Answer 11

• materials
• finishes
• varnishes
• paints
• dyes
• polymers

Question 12

what is phosphorescent pigment?

Answer 12

glow in the dark material that responds to light

Question 13

uses for phosphorescent pigment

Answer 13

fire exit signs
stickers
toys

Question 14

what is photochromic pigment?

Answer 14

changes colour or opacity due to UV light exposure [reversible]

Question 15

uses for photochromic pigment

Answer 15

glasses
clothes
novelty items
stationary

Question 16

what is electroluminescent wire?

Answer 16

copper wire coated in phosphor which glows when an alternating current passes through

Question 17

how is electroluminescent wire different from LED ?

Answer 17

produces a 360 degrees unbroken thread of light

Question 18

properties of electroluminescent wire and uses?

Answer 18

• flexible
• used outdoors
• lighting
• accessories
• bikes
• costumes

Question 19

what are piezoelectric materials?

Answer 19

convert mechanical energy to electrical energy and vice versa

Question 20

how do piezoelectric materials work?

Answer 20

pressure and vibrations are converted to electrical charge which can be stored for later use

Question 21

what materials are piezoelectric ?

Answer 21

• crystal
• ceramic
• bone
• viruses

Question 22

uses for piezoelectricity?

Answer 22

• sparks in lighters
• trip burglar alarms
• generate sound for fire alarms

Question 23

how do ultrasonic submarine detectors work?

Answer 23

• grid of quarts held between steel plates
• resonates when electric current is applied
• cell emits sound underwater
• terrain measured by timing the echo return