9.2 - Glass and Ceramic

Glass

• Glass is made from silica.
• Silica is a compound containing silicon dioxide and occurs naturally in sand.
• Pure silica is melted at about 1500°C, turned into a liquid and shaped into glass.

Type and composition	Characteristics
Fused silica glass: silica	Resistant to heat; inert to chemicals
Soda-lime glass: silica, calcium carbonate, sodium carbonate	Low melting point; easily shaped
Borosilicate glass: silica, boron oxide, sodium oxide, aluminium oxide	High resistance to heat and chemicals compared with soda-lime glass
Lead crystal glass: silica, lead(II) oxide, sodium oxide	Low melting point; high refractive index

Ceramic

• A ceramic is made of non-metallic materials formed by the action of heat at a high temperature.
• Ceramic is made from clay; the main component of clay is aluminium silicate.
• Characteristics of ceramic:
  • resistant to high heat and pressure;
  • very hard but brittle;
  • inert to chemicals and does not rust;
  • good heat and electrical insulator.

Applications of Glass and Ceramic

Glass

• Laboratory apparatus such as beakers and conical flasks use borosilicate glass because it is highly resistant to heat and chemicals.
• Glass bulb covers usually use soda-lime glass because it is heat-resistant and easily shaped.
• Glass prisms use lead crystal glass because its high refractive index enables the dispersion of light to be studied.
• Transparent windows allow light to enter a house.

Ceramic

• Crockery: heat-resistant and does not corrode.
• Artificial teeth: hard, strong and inert to chemicals.
• Floor tiles: shiny, making the floor appear clean and attractive.
• Flower pots: hard and strong.