Glass and Ceramics

  1. The most important component of glass and ceramics is silica ( silicon(IV) dioxide, SiO2).
  2. Both glass and ceramic have the following properties:
    1. Hard and brittle
    2. Do not conduct heat electricity
    3. Inactive towards chemical reactions
    4. Weak when pressure is applied
    5. Can be cleaned easily

Glass

  1. It is a mixture of two or more types of metallic silicates but the main component is silicon(IV) dioxide.
  2. Glass has the following properties:
    1. Transparent and not porous
    2. Inactive chemically
    3. Can be cleaned easily
    4. Good insulators of heat and electricity
    5. Hard but brittle
    6. Can withstand compression but not pressure

Soda lime,glass

Composition: SiO2 – 70%, Na2O – 15%, CaO – 10%, Others – 4%

Properties:

  1. Low melting point (700°C)
  2. Moldable into shapes
  3. Cheap
  4. Breakable
  5. Can withstand high heat

Uses: Glass containers, Glass panes, Mirrors, Lamps and bulbs, Plates and bowls Bottles

Lead glass (crystal)

Composition: SiO2 – 70%, Na2O – 20%, PbO – 10%

Properties:

  1. High density and refractive index
  2. Glittering surface
  3. Soft
  4. Low melting point (600°C)

Uses: Containers for drinks and fruit, Decorative glass and lamps, Crystal glassware, Lenses for spectacles

Borosilicate glass (Pyrex)

Composition: SiO2 – 80%, B2O3 – 13%, Na2O – 4%, AI203 – 2%

Properties:

  1. Resistant to high heat and chemical reaction
  2. Does not break easily
  3. Allows infra-red rays but not ultra-violet rays

Uses: Glass apparatus in laboratories, Cooking utensils

Fused silicate glass

Composition: SiO2 – 99%, Other – 1%

Properties:

  1. High melting point (1700°C)
  2. Expensive
  3. Allows ultraviolet light to pass through
  4. Difficult to melt or mould into shape

Uses: Scientific apparatus like lenses on, spectrometer, Optical lenses, Laboratory apparatus

Ceramics

    1. Ceramic is a substance that is made from clay and hardened by heat in a furnace maintained at a high temperature.
    2. Clay is composed of aluminosilicate with sand and iron(III) oxide as impurities.
    3. Examples of ceramics include
      1. Tiles
      2. Cement
      3. Bricks
      4. porcelain
  1. The properties of ceramics include the following:
  2. The differences between the properties of ceramics, metals and non-metals are given below

Property Metals Non-metals Ceramic
Hardness Hard but malleable and ductile Soft and brittle Hard but brittle
Density High Low Average
Melting point High Low Very high
Resistance to heat High Low Very high
Heat and
Electrical conductivity
Good
conductor
Good
insulator
Good
insulator
Chemical reactions Corrodes Corrodes Stable, does not corrode

Comparing Glass and Ceramic


Common Properties of Glass and Ceramics

  1. Hard
  2. Strong but brittle
  3. Chemically inactive
  4. Poor conductor of heat and electricity
  5. High melting point – heat resistant
  6. Cannot be compressed easily

New Uses of Glass and Ceramics

Photochromic Glass
  1. Photochromic glass is very sensitive to light.
  2. It darkens in the presence of bright light and lightens when the amount of sunlight lessens.


Conductive Glass
  1. Conducting glass is a type of glass which can conduct electricity. It is obtained by coating a thin layer of a conducting material around the glass, usually indium tin(IV) oxide.
  2. It is used in the making of Liquid Crystal Display (LCD)

Car Engine Block
  1. When clay is heated with magnesium oxide, the ceramic that is produced has a high resistance to heat.
  2. This material is used to build the engine blocks in cars as they can withstand high temperatures.

Superconductors
  1. Superconductors are electrical conductors which have almost zero (0) electrical resistance. Therefore, this conductor minimises the loss of electrical energy through heat.
  2. Yttrium barium copper oxide is a type of ceramic superconductor
  3. Superconductors are used to make magnets which are light but thousands of times stronger than the normal magnet.