STATE OF MATTER :

CERAMICSREBECCA, ADIB, ZULKHILMY,

FARAH

STRUCTURE OF CERAMICS

Ionic bonded ceramics

Covalently bonded ceramics

PROPERTIES OF CERAMICS Strength The strong bonds holding the atoms (or ions)

together in three dimensions will make the ceramic hard and strong, but also brittle.

Melting Point - This type of giant covalent structure is

thermally very stable and has a very high melting and boiling points because of the strong covalent bond network.

- A relatively large amount of energy is needed to melt or boil giant covalent structures. 

Conductivity They are usually poor conductors of

electricity because the electrons are not usually free to move as they can in metallic structures.

USES OF CERAMICSMagnesium Oxide Special characteristic: -the good electrical insulation properties -its thermal conductivity.

Therefore, it is used as;- Electrical insulators in industrial electrical

cables where magnesium oxide surrounds the copper wires.

- As a refractory in furnace lining- In fire- resistant wall board.

Aluminium Oxide -Special characteristic: a high strength and hardness, high resistance to wear and corrosion, high thermal conductivity, excellent insulation properties, high toughness and high-temperature strength.

Therefore, it is used as:- refractory in furnace lining- As an abrasive for grinding hard materials : they don’t

conduct heat or melt when heat is given off during grinding.

- In transparent aluminium oxide- scandium windows for furnaces and for millitary vehicles.

Silicon oxide Special charateristic:-high-temperature strength.

Therefore, it is used as:- Refractory in furnace linings- As an abrasive: for example sand paper- In the manufacture of glass.

DICTIONARY Abrasive : a substance or material such as

sandpaper, pumice, or emery, used for cleaning, grinding, smoothing, or polishing

Furnace: a device used for heating. Furnace lining: a protective and insulating layer

of heat resistant material. This layer serves to protect the furnace part from the extreme heat developed during smelting operations. It also prevents excessive heat loss from the external furnace surfaces making the process more efficient. Also known as refractory materials, furnace lining materials are typically ceramics or combination metal/ceramics.