Smart and Modern Materials Flashcards
What are thermochromic materials?
Thermochromic materials can change colour at lower temperatures. There are two main types of materials which are used to make thermo chromic effects: some use liquid crystals and other use organic dyes known as leucodyes. Depending on the temperature thermo chromic materials show a different colour.
Uses of thermo-chromic materials
- baby thermometer
- baby spoons
- Sports equipment
- Gimmick products ( mugs, birthday cards, album covers, mood rings and even some beer cans)
What are leucodyes?
They are organic (carbon -based) chemicals that change colour when heat energy makes their molecules shift back and forth between two subtly different structures- known as the leucodyes and non-leucodyes forms. These forms absorb and reflect light differently so appear very different colours when printed in a material such as paper or cotton ( e.g checkout receipts). However, the print can fade relatively quickly when exposed to sunlight.
How do liquid crystals work?
Incoming light rays hit the layers of liquid crystals and reflect back out again, with out going rays interfering (adding together or subtracting from one another) to produce light if a particular colour, in this case blue. The colour of the reflected light depends on how closely the crystals are together. Cooling liquid crystals makes them move further apart, changing the way outgoing waves interfere and making the reflected light redder than before. This type of reflection is known as iridescence.
What are the advantages of liquid crystals?
- Low power consumption compared with traditional alternatives - therefore, the battery lasts longer. This means it can be made smaller which has led to miniaturisation.
- It is very compact and takes up little space
- Very thin compared to alternative display options
- Adaptable for numerous uses in commercial and industrial settings
- Produces a lot less heat than alternative display options
What are the disadvantages of liquid crystals?
- Limited viewing angles: colours and brightness may seem distorted from certain angles
- Can suffer from motion blur, especially in fast paced scenes. This can lead to eye strain or headaches.
- More fragile than their glass alternatives.
- Visibility isn’t so good when used outdoors. However, some do have anti- glare coatings or higher brightness settings.
What are Shape Memory Alloys (SMA)
It is an alloy which can be deformed when cold but it can return to its pre-deformed shape when heated. They just must be trained at a particular temperature.
What are the uses of Shape Memory Alloys?
- Dental implants
- Surgical tools
- Glasses frames
- Heart stents
- New designs for wheels
- Springs
- Paper clips
- Opening of greenhouse windows
- Power generation
What are the advantages of Shape Memory Alloys?
- Goes back to its original state when applied with the temperature its was trained at
- Super elasticity
- Space saving
- Brilliant mechanical properties against fatigue
- Super lightweight
What are the disadvantages of Shape Memory Alloys?
- It must be trained
- Really expensive
What is Quantum Tunnelling composite ( QTC )?
It is a composite material, composed of an insulating material and particles of a conducting material. The conducting particles are suspended within the insulator. In normal use QTC will not conduct electricity. However, when pressure is applied, the conducting particles are pressed together, allowing electricity to flow through them. ( Electricity tunnels through the non-conductive material). They have been developed so more current can flow through then the more pressure which is applied. This is because more pressure means less resistance to the flow of electricity.
What are the uses of Quantum Tunnelling composite?
- Can be used in touch screen technology
- Can be used to create feeling in prosthetic limbs for amputees
- Used in blood pressure cuffs to reduce inaccurate readings and increase current.
- Pressure sensitive bandages
- In handle of a drill bit instead if a switch
What are the advantages of Quantum Tunnelling composite?
- Can be firmed or moulded into virtually any size, thickness or shape
- Durable, it has no moving parts which can wear out
- Mechanically strong
- Can be made to withstand extreme temperature limits
- Versatile, both electrically and physically
- Safe - the material is a contactless switch, ideal for spark free operation
- Can be directly connected to standard electronic and electrical devices.
- It is very flexible
What are thermo-ceramics?
Thermo-ceramics convert thermal energy into electricity and vice versa by using the Seebeck effect, where temperature difference across a material creates an electrical potential or the Peltier effect, where an electrical current through a material causes a temperature difference. It has a very high thermal conductivity, which means they can efficiently transfer heat. When a temperature difference is applied across a thermo electric material, a voltage is generated and conversely, when a voltage is applied a temperature difference is created.
What are the advantages of thermo-ceramics?
They are highly resistant to heat, making them ideal for high temperature environments.
- They are are extremely good thermal insulators, minimising heat loss or preventing heat from reaching sensitive components. This can also increase efficiency by increasing energy consumption
- They are highly durable and resistant to wear, corrosion, and thermal shock, increasing the longevity of the product.
- It is resistant to chemical corrosion
- It is very lightweight making it good for applications like aerospace and automotive engineering.
What are the disadvantages of thermo-ceramics?
- Although, they are very brittle. They can crack or fracture easily under mechanical stress or impact.
- They can be costly to produce or purchase making mass production even more costly
- Manufacturing thermo ceramics is complex and requires advanced processing techniques which can increase production time and cost.
- They have lower mechanical strength compared with metals or other construction materials.
- It has very limited flexibility, therefore it can’t accommodate expansion or movement.
What are the uses of thermo-ceramics?
- turbine blades in jet engines
- turbo chargers in racing cars
- tips on cutting tools such as drill bits
- high end skateboard bearings
- metal cutting tools.
What is reactive glass?
It is a type of glass that changes its properties in response to external stimuli such as light, heat or electricity. It can switch between transparent or opaque states or adjust its tint to control the amount of light and heat passing through. There is lots of different types of reactive glass.
The technology behind reactive glass depends on the type used. For example, for electronic reactive glass the stimulus is electricity and it works by ions moving to change the tint. Some change with UV light by the molecules darkening in the sunlight or temperature can be a stimulus and the tint would then just change with heat.
What are the adavantages of reactive glass?
- It can help controlling solar heat gain by darkening automatically in response to light. This reduces the need for air conditioning, leading to energy savings.
- It allows more natural light indoors while preventing glare, making the indoor environment more comfortable and reducing the need for artificial lighting.
- It can be used in various colours and patterns, offering design flexibility.
- It has a sleek, futuristic appearance
- The glass can adjust its tint without manual intervention, reducing the need for curtains or blinds.
- Some types of reactive glass have soundproofing properties, reducing external noise pollution
What are the disadavantages of reactive glass?
- It is more costly than standard glass both in terms of materials and installation and repairs or replacement can be costly.
- They can sometimes take quite a long time to alter their tint, it can take up to several minutes to change from one state to another.
- Some require an external power source to switch between states, which may increase energy consumption
- Requires specialised installation and may not be compatible with existing window frames without modifications.
- It may not function as well in extreme temperatures.Usually a limited range of tints and colours which may not suit all design preferences.
What are the uses of reactive glass?
- Apartment or office block windows because they can control the amount of light which can make its way in
- conservatories
- glass roofing
- windows
- privacy screens
- energy efficient buildings.
What are photo-chromic materials?
Photo chromic materials change colour with light intensity. They change there optical properties (such as colour or transparency) when exposed to UV light. This reversible reaction occurs due to a chemical reaction at the molecular level, allowing the material to switch between a clear and tinted state depending on light exposure.
What are the advantages of photo-chromic materials?
- It has automatic light adaption which can reduce glare and eye strain.
- Blocks harmful UV rays, protecting our eyes and skin from sun damage.
- They can be used to regulate heat and light minimising cooling costs
- They generally have long lasting colour changing capabilities
- Used in fashion and textiles for dynamic colour changing designs.
What are the disadvantages of photo-chromic materials?
- Some materials take seconds to minutes to fully change colour especially in colder temperatures.
- Does not darken significantly in artificial light, making it ineffective indoors.
- UV light can degrade the material reducing its responsiveness
- There is generally quite limited colour options compared to other dyed or tinted materials
- Far more expensive than standard lens, windows or coatings due to the advanced technology.
