Posted on December 14th, 2009 by Technology Department
Millions of years ago, man used to manage simples materials, such as wood, to make unsophisticated tools or constructions Nowadays, man has invented new materials which can be used in many different situations, even in our own bodies ( See illustration on the right where old tooth are replaced by implants.
Materials and Components
- Choosing the correct material for any particular task is essential for a manufacturing activity. Materials can be natural or artificial. Natural resources are split into 3 categories. 1. Animal 2. Vegetable 3. Mineral
Artificial Materials: ARE THOSE WHICH HAVE BEEN MADE BY MAN
TYPES OF MATERIALS
1º Wood: Divided into two major classifications: Hardwoods and Softwoods. 2º Metals. There are two significant groups of metals: Ferrous metals, which contain iron and non-ferrous metals, which do not contain iron. Examples of Non-ferrous metals are: Aluminium, Copper, Gold, Silver ...
Materials Properties of MaterialsProperties of materials can be divided into physical, chemical and ecological
Electrical Conductivity is when electricity can run though the material. Examples: Steel is a good conductor Wood isn't a good conductor
Optical propertiesHow materials behave when light touches them. They can be classified into: a) Opaque: No light travels through them. e.g wood b) Transparent: All light travels through them and you can see what's behind the materials. e.g glass in a window c) Translucent: All light can travel through them but you cannot see what's behind them e.g frosted glass
See examples on page 75
What is a thermal conductor and what is an insulator ?
It is the ability of the material to conduct heat. e.g. In a saucepan there is a metal body for thermal conductivity and plastic handles for thermal insulation. Thermal Insulation = It is a bad thermal conductor
Dilation: When material expands ( gets bigger ) due to heat Contraction: When material gets smaller due to heat.
To think about: Why are rails separated by a gap?
Fusibility is the ability of a material to change into a liquid when heated to its melting point. Examples of melting points: Iron’s melting point...........1535 ºC
Copper’s melting point..........1083 ºC
The ability of materials to conduct sound. To think about. Can you speak on the moon. I mean, can your partner hear what you say?. Write some examples of good and bad conductors
Oxidation.The change that occurs to most metals when in contact with air or/and water