Evaluating uses of composite materials

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Malaysia SPM Form 4 Chemistry, Chapter 9: Manufactured Substances in Industries

Contents 1 Introduction 2 Uses of Composite Materials 2.1 Reinforced concrete 2.2 Optical fibre 2.3 Photochromic glass 2.4 Plastic reinforced with glass 2.5 Superconductor 3 Composite Materials to Fulfill Specific Needs

[edit] Introduction

• Composite materials are substances which contain 2 or more materials that combine to produce new substances with different physical properties from the original substances.
• They are used to make various substances in daily life because of the following reasons:

1. Metals corrode and are ductile and malleable
2. Glass and ceramics break easily
3. Metals are good conductors but have high resistance, leading to loss of electrical energy as heat
4. Plastics and glass can withstand heat to certain level only.

• Composite materials have been created to overcome these problems and to make materials stronger, more long-lasting and light for specific purposes.
• Some composite materials and their components are:

[edit] Uses of Composite Materials

[edit] Reinforced concrete

concrete (cement, sand, stones), steel

• 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.
• Steel pillars are too expensive and can rust.
• Reinforced concrete, containing steel rods in the concrete pillars, can make them stronger and able to support larger loads. It also does not rust.

[edit] Optical fibre

SiO2, Na2CO3, CaO

• This is a fine transparent glass tube that is made of molten glass. Glass cannot conduct electricity or electronic data in the form of electrons. But optical fibre allows light to be transmitted through the tube so that data is transmitted at a faster rate.
• In telecommunications, light has replaced electrons as the transmitter of signals. This light transmits signals through optical fibre and the field is called optoelectronics.
• Optical fibre is also used in the medical field as

1. laser to do operation
2. endoscope to examine the internal organs of patients

[edit] Photochromic glass

glass, AgCl (or AgBr

• Glass is transparent and not sensitive towards light.
• Photochromic glass contains AgCI or AgBr which causes the glass to darken in sunlight and lighten in the absence of sunlight. (See 9.5.)
• It is used to make photochromic lenses of spectacles and protects our eyes from extreme sunlight.

[edit] Plastic reinforced with glass

fibreglass and polyster resin

• While plastic is light and hard, it is brittle. Glass is harder than plastic but breaks easily. Thus fibre glass is obtained by adding a polyster resin to molten glass. It cannot be compressed easily and is more tensile than the original materials.
• 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.
• It is used to make racquets, construction panels, electrical appliances, pipes, and water tanks.

[edit] Superconductor

Itrium oxide (Y203), BaCO3, CuO

• It is a substance with almost nil resistance. Thus it saves electricity.
• Copper shows superconductor properties only at -270°C. Thus the superconductor, a mixture of CuO, Y203, and BaO, results in a ceramic called perovskite or YBCO. All the materials used to make this composite substance are not electrical conductors in their original forms, but as a superconductor, it conducts electricity without loss of energy. (See 9.5.)

[edit] Composite Materials to Fulfill Specific Needs

• Composite materials are needed in various fields, for example:

1. In the medical field: to replace organs in the form of plastic composite organs.
2. Car parts now use composite materials instead of iron and steel. This increases the speed of the car (car is lighter) and saves on fuel consumption.
3. Stronger buildings are built by using reinforced concrete.