CE 1201 Properties of Materials

Metals and Alloys: Steel, Cast Iron, Aluminum, Zinc, Copper, Brass, Bronze
Ceramics and Glasses: Alumina, Magnesia, Silica, Silicon Carbide, Silicon Nitride
Polymers: Polyethylene, Polystyrene, Polyvinylchloride, Epoxies, Natural Rubber, Wood
Semi Conductors: Silicon, Germanium, Gallium Arsenide
Composites: Concrete, Plywood, Fiberglass

Metals are composed of metallic elements and non-metallic elements in small amounts
Atoms in metals are arranged in a very orderly manner and are relatively dense
Metals show good mechanical properties and have large numbers of nonlocalized electrons
Many properties of metals are directly attributable to these electrons
Pure metals are low in strength and do not possess the required physiochemical and mechanical properties
Alloys are made by melting or sintering two metals or metal and a non-metal

Ferrous metals are metals that contain iron as their base constituent
Iron imparts magnetic properties and makes them prone to corrosion
Examples: Wrought iron, Cast iron, Steel
Non-ferrous metals do not have iron in their composition and do not possess magnetic properties
Examples: Copper, Aluminum, Zinc

Produced by melting pig iron with some scrap in a Cupola Furnace
Has 2-4% carbon content
Exists in three different forms: White cast iron, Gray cast iron, and Malleable cast iron
Used in producing machine parts, bed plates, and drain covers

Formed by rapidly cooling molten iron
Has low carbon and silicon levels
Has a white fractured surface due to the presence of cementite
Has high compressive strength, hardness, and abrasion resistance
Used in teeth of a backhoe's digging bucket, coal pulverisers, and grinding mills

Formed by heat treating white cast iron to convert cementite into graphite nodules
Has a lower carbon percentage than other cast iron
Used in producing washers and other machinery parts### Properties and Uses of Malleable Cast Iron
Malleable cast iron is a very tough iron that is machinable and ductile.
Its properties make it suitable for:
- Parts that are to be pierced, coined, or cold formed
- Parts requiring maximum machinability
- Parts requiring wear resistance
- Parts that must retain good impact resistance at low temperatures

Ferrous alloys are alloys that contain iron as their base constituent.
Examples of ferrous alloys include:
- Silicon steel
- Tungsten steel
- Stainless steel

Silicon steel is an alloy of iron and silicon with important electrical applications (e.g. motors, transformers, etc.).
It is commonly referred to as electrical steel.
Silicon additions improve magnetic softness and increase electrical resistivity.
Properties:
- High electrical resistivity
- Improved magnetic properties
Uses:
- Electrical motors
- Transformers
- Power generators

Tungsten steel is an alloy consisting of tungsten (W), steel, and traces of carbon.
It has a series of excellent properties, including:
- High hardness
- High wear resistance
- High strength
- High toughness
- High heat resistance
- Corrosion resistance
Uses:
- Drill bits
- Boring cutters
- Saw blades

Stainless steel is an alloy of steel that contains a minimum of 12% chromium.
The chromium addition results in producing a thin layer of oxide on the surface of the steel, known as the 'passive layer', which prevents corrosion.
Increasing the amount of chromium gives increased resistance to corrosion.
Properties:
- High strength
- Corrosion resistant
- Less electrical conductivity
Uses:
- Cookware
- Surgical equipment
- Civil engineering constructions
- Jewelry and watches

Non-ferrous metals and alloys are metals that do not have iron in their composition.
They do not possess any magnetic properties.
Examples of non-ferrous metals and alloys include:
- Copper
- Aluminium
- Zinc
- Brass
- Bronze