8.4.1 Composite Materials

1. Composite materials are substances which contain 2 or more materials that combine to produce new substances with different physical properties from the original substances.
2. Some composite materials and their components are:

Reinforced Concrete

Component: Concrete (cement, sand, stones), steel

1. Ordinary concrete is strong but heavy. Concrete pillars must be big to support the weight. They take up space and cannot withstand stress for example from earthquakes.
2. Steel pillars are too expensive and can rust.
3. Reinforced concrete, containing steel rods in the concrete pillars, can make them stronger and able to support larger loads. It also does not rust.

Optical Fibre

Component: SiO₂, Na₂CO₃, CaO

1. This is a fine transparent glass tube that is made of molten glass.
2. In telecommunications, light has replaced electrons as the transmitter of signals. This light transmits signals through optical fibre.
3. Optical fibre is also used in the medical field as
1. laser to do operation
2. endoscope to examine the internal organs of patients

Photochromic Glass

Component: glass, AgCl (or AgBr

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.

Fibreglass

Component: Fibreglass and polyster resin

1. Fibre glass is obtained by adding a polyester resin to molten glass. It cannot be compressed easily and is more tensile than the original materials.
2. Fibre glass is light, withstands corrosion, can be cast into different shapes, is impervious to water, not very flammable, not brittle and stronger than even steel.
3. It is used to make racquets, construction panels, electrical appliances, pipes, and water tanks.

Superconductor

Component: Ytrium oxide (Y₂O₃), BaCO₃, CuO

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.