Engineering Materials part 1

11EGS 2014

Mr Miller

Classification of materials Materials are classified according to

their properties. These properties can be classed into three different categories:

Natural properties (e.g. iron ore); Manufacturing properties (injection

moulding); In-service properties (corrosion resistance).

Natural properties How the material is found in its natural

state. Like what? Aluminium =

Steel =

Glass =

Manufacturing processes How the material responds to certain

techniques. For example?

In-service properties How that material responds to different

operating environments. For example?

Elements, compounds, solutions and mixtures All materials, regardless of their state,

can be classed as either an element, a compound, a solution or a mixture.

Which one they are will depend on their chemical composition and their structure.

Elements: Refer to a periodic table of the

elements. They are the building blocks for all

matter and cannot be broken down further.

Most materials do not occur naturally as pure elements.

Can you name ten elements?

Solutions A solution is where one substance

dissolves in another, such as sugar in tea or salt in water.

Metals can dissolve in one another to form solutions.

Formed by mixing a solute (the material added) and a solvent (the material the solute is added to).

Examples?

Compounds Are a result of two or more elements

that combine chemically in a fixed proportion.

Unlike elements, compounds can be broken down into singular elements.

Examples?

Mixtures Are the result of two or more pure

substances (elements OR compounds) mixed together mechanically without regard to fixed proportion.

Just like in…

Metals and non-metals How many of the 90 naturally occurring

elements are metals?

Metals Non-metals

Metals Societies and individuals have used

metals since before the Bronze Age when copper was used before 4000BC. Although the Iron Age was around 1000BC, our society is still highly dependent on iron (now alloyed with carbon to form steel).

Metals timeline

Naturally occurring metals Examples?

Alloys Commonly confused as an aluminium

based metal, alloys are a mixture of two or more materials. One of these must be a metal, and the alloy generally has metallic properties.

Some examples of alloys include:

Ceramics Ceramics have been used for centuries

and are now finding new uses due to their hardness and good thermal properties.

Ceramics form naturally as rocks: Granite (igneous – formed by volcanic

activity); Sandstone and shale (sedimentary) Slate and marble (metamorphic – igneous or

sedimentary rocks that have been exposed to extreme heat and pressure resulting in a change in structure.

Applications of ceramics Used where metals are unsuitable, e.g.

furnace linings. Most new structures incorporate

concrete of which ceramic materials are the predominant component.

Modern ceramics are now being tested for use in turbine and diesel engines, as their high temperature stability and low thermal expansion allow improved fuel efficiency.

Polymers Polymer is a term that encompasses a

large and diverse group of materials that has had a big impact on industrial and consumer applications since World War II.

Polymers are often termed organic, due to carbon being the primary constituent.

Although most polymers are synthetic, there are some natural polymers, such as shellac, natural rubber and cellulose fibres.

All other polymers used by an engineer are synthetic.

Applications Polymers are extremely important to the

modern engineer. Their use is great and varied, and has

revolutionised areas such as:

Biological materials Biological materials refers to materials

that are a result of the lifecycle of a plant or animal.

They include wood, wax, leather, diatomite and limestone.

Materials such as paper, composite wood products and lime are also biologically based.

Composites Composites are materials that are

combined together to capitalise on the desirable properties of each.

__________________ is an example of a composite, whereby a very fine __________________is combined with a thermosetting resin material. In this case the ________________ provides good tensile strength whilst the resin gives it toughness.

Examples of composites?