SC26 Flashcards
(21 cards)
What are ceramics?
non metallic materials e.g. china, bricks and glass
Their atoms are held together by covalent and/or ionic bonds
How are clay ceramics made?
Made from clay, moulded into the desired shape.
When the clay is heated to a very high temperature, tiny crystals form and join together in a regular way to form a giant structure- This makes clay ceramics opaque
How are ceramics made?
- They are made by heating their components to very high
temperatures
Give 3 examples of clay ceramics and tell me where they are used.
- Bricks (for building houses)
- Porcelain (for electrical pylon insulators)
- China (to make cups, plates)
What are the usefull properties most ceramics have?
. high melting points and heat resistant
2. stiff, strong when compressed and brittle
3. good insulators of heat and electricity
4. Very unreactive
How is glass made?
- It is made by melting sand, then allowing it to cool and solidify.
What are the properties of grass?
- Glass is transparent, hard, stiff, brittle, poor electrical conductor, high melting point
Uses of glass?
- Uses: window glass, shower screens
Give an examples of a coposite.
For example, pykrete consists of ice and 14% wood pulp which separates out
when the ice melts.
What is a composite?
A composite is a mixture of two or more materials, combined to
produce a material with improved properties.
The individual materials are visible in the composite material
and can be separated byphysical means.
What is a reinforced composite?
Reinforced composite is a mixture of two or more
materials combined to produce a material with
improved strength.
How is concrete made to be reinforced?
made by mixing cement, sand, aggregate(small stones and gravel) and water. The
sand and aggregate form the reinforcement of the concrete. The reinforcement is bonded together by cement, which forms the matrix
How is steel-reinforced concrete better?
Steel has higher tensile strength (resistance to stretching) and higher compressive strength(resistance to squashing) . This composite is strong in tension and in compression and is less dense and cheaper than steel alone
Where is steel-reinforced concrete used?
Reinforced concrete has many uses, including railways and as a structural material to support buildings.
How is wood a narutal composite material?
Wood is a natural composite material consisting of cellulose fibres in a matrix of a polymer called lignin. It is stronger along its grain than it is across its grain.
How is plywood made and where is it used?
Plywood is a mixture of odd numbers of thin sheets of wood glued at right angles to the sheet below it.
Plywood is used in the furniture industry.
How is fibreglass made?
Fibreglass is a composite made by covering thin glass fibres with a polymer resin that sets hard around the glass fibres. Fibreglass can be moulded easily to produce different shapes.
What are the properties of fibreglass?
Properties of fibreglass:
* It is strong and tough to withstand knocks
* It is lightweight to move easily
* It is flexible (it will flex without breaking under stress)
* Used for making the hulls of boats, large water tanks and car bodies.
What are nanoparticles made out of, and what is their size?
Nanoparticles are tiny particles made up of a few hundred atoms
and are 1-100 nm in size
Nanoparticles cannot be seen with the naked eye, or even an
optical microscope – an electron microscope is needed to observe
them.
They are larger than atoms and small molecules but smaller than
cells (a bacterium is 1000 nm long). Nanoparticles cannot be seen with the naked eye, or even an
What is the name given to Substances that consist of nanoparticles?
Substances that consist of nanoparticles are described as being nanoparticulate.
What are some uses of nanoparticles?
- Nanoparticles of titanium dioxide are used in sunscreens because they absorb harmful ultraviolet radiation but are transparent/almost invisible.
- Nanoparticles of titanium dioxide catalyse the breakdown of dirt, leaving a transparent coating. So it can be used to clean stain-resistant clothes.
Tiny electronics
sunscreen
synthetic skin
