SUBJECT:� BASIC TECHNOLOGY
- NERDC, Basic Technology for JSS, Book 1
- EVANS, Basic Technology for JSS, Book 1
TOPIC:� IDENTIFICATION OF CERAMICS & GLASSES
- Ceramic materials and properties
- Glass materials and properties
CERAMIC MATERIALS AND PROPERTIES
Ceramic is a hard brittle heat-resistant material made by firing a mixture of clay and chemicals at high temperature. The ceramic products are products made from clay and chemical materials.
Examples are clay pots, marbles, tiles , water-closet, water-jug, glass , water basins etc.
PROPERTIES OF CERAMIC MATERIALS
- Ceramics are resistant to corrosion.
- They can withstand very high temperature e.g. furnace and oven.
- They are electrically resistant.
- They are usually hard and strong.
- They have compressive strength.
- They can easily be molded when wet.�
- They can easily break when dropped on the ground.
- What is a ceramic?
- List five properties of ceramics.
GLASS MATERIALS AND PROPERTIES
Glass is a type of ceramic. Glass is a hard usually transparent material made from sand, lime, potash, soda and lead oxide. To produce glass, these raw materials are mixed and placed in a furnace and melted. It is then formed into the desired objects.
Making of glass involves the following stages:�
- Mixing the raw materials;
- Heating (firing) to produce molten glass;
- Cooling to form rigid glass;
- Heating again and allowing to cool gradually (annealing).
PROPERTIES OF GLASS
- It is brittle,
- It is transparent and�
- Resistant to corrosion.
Examples of glass products are cups, bottles, mirrors, glass tubes, electric bulbs, glass window, glass doors, eye glasses and lenses.
- What are the materials for making glass?
- List three properties of glass.
- Which of the following is not used in making glass? (a) Sand (b) lime (c) potash (d) clay
- Glass is used to manufacture eye glasses and lenses because of this property. Choose from the options.� (a) Brittleness (b) resistance to corrosion (c) transparent (d) resistance to heat.
- Which of the following is not used in making ceramics? (a) lime (c) cement (c) mud (d) clay.
- The following are products of ceramics, except (a) flower vase (b) tiles (c) wash basin (d) electric bulb.
- What are ceramics and glass?
- List two differences between the two.