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 • 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).
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.
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.