MATERIALS

MATERIALS

1. FERROUS MATERIALS - CONTAIN IRON AND THEY ARE ALL ALLOYS

   • Cast iron 1200 degrees- Hard skin, soft underneath but brittle and corrodes by rusting
     • can be used to create parts with complex shapes and they can be made by casting
   • Stainless steel 1400 degrees - Hard and tough, resistance to wear and corrosion
     • can be use to produce kitchen equipment and cuterly
   • Mild steel 1600 degrees- Tough, ductile , malleable, good tensile strength but poor resistance to corrosion
     • can be used for general purposes for engineering materials
   • High carbon steel 1800 degree- even harder than medium carbon steel and more brittle but can be heat-treated to make it harder and tougher
     • can be used to produce parts such as cutting tools and ball bearings

2. NON- FERROUS- DO NOT CONTAIN IRON

   • Aluminium 600 degrees its composition is pure Aluminium- Good to weight ratio, light, soft, ductile , good conductor of heat and electricity.
     • kitchen equipment, windows frames and cast components
   • Copper 1080 degrees its composition is pure copper- malleable and ductile , good conductor of heat and electricity and resistant to corrosion
     • water piles, electrical wire and decorative goods
   • Brass 900-1000 degree c, its composition is alloy- Resistant to corrosion, quite hard, good conductor of heat and electricity
     • Water taps and ornaments
   • Tin 230 degree c, its composition is pure tin- soft, weak, malleable, ductile and resistant to corrosion
     • Used for coating steel to form a tin plate, soft solder.

3. SMART MATERIALS- are materials that have one or more properties that can be importantly changed in a controlled manner by external stimuli such as STRESS, TEMPERATURE, pH, MOISTURE, ELECTRIC or MAGNETIC FIELDS

   • PIEZOELECTRIC-Produces voltage when stress is applied, this effect also applies in a reverse manner a voltage across a sample will produce stress inside the sample.
     • Can be bend, expand or contract when stress is applied
   • Shape-Memory alloys
     • large deformation can be generated and recovered through stress or temperature change (pseudoelasticity)
   • Magnetostrictive
     • show change in shape under a influence of magnetic field and also show change in their magnetization under the impact of mechanical stress
   • Magnetic Shape Memory alloys
     • change their shape responding to an important change in a magnetic field
   • Smart Inorganic polymers
     • shows tunable and responsive properties
   • pH- sensitive polymers-
     • Change in volume when the pH of surrounding medium changes
   • Temperature responsive polymers
     • undertake changes in temperature
   • Halochromic
     • change their colour as a result of changing acidity. for example one application is for paints that changes colour to show corrosion in the material underneath them
   • chromogenic system
     • change colour in reponse to electrical, optical or thermal changes
   • photomechanical material
     • Changes shape when exposed to light.
   • polycaprolactone
     • molded by immersion in hot water
   • Self- healing materials
     • Have the innate ability to be able to damage due to normal usage therefore expanding the materials lifetime
   • Dielectric Elastomers
     • produce large strains up to 500%under the effect of an external electric field
   • Thermoelectric Materals
     • are used to build devices that convert temperature differences into electricity
   • Magnetocaloric materials
     • A compound that undertakes a reversible change in temperature upon exposure to a changing magnetic field
   • Electrochromic
     • changes colour or density depending on the application of voltage for example liquid crystal displays
   • Thermochromic
     • changes in colour depending on their temperature
   • Photochromic
     • Change colour in response to light for example light sensitive sunglasses that darken when the sunlight is too bright

4. POLYMERS- Very large molecules created when a lot of smaller molecules join together, end to end (create a really long chain) .The smaller molecules are known as monomers

   • Alkenes can be used as monomers this is because they are unsaturated
     • Ethene is polymerised to shape poly( ethene), known as POLYTHENE
       • plastic bags and bottles
     • Propene is polymerised to shape poly( propene), known as POLYPROPYLENE
       • Crates and Ropes
     • Chloroethane is polymerised to shape poly(chloroethane), known as PVC
       • Water pipes, and insulation on electricity cables
   • polymers are resistance to corrosion and chemicals,
   • They have low thermal and electrical conductivity
   • High strength to weight ratio and low density
   • Noise Reduction
   • Easy to manufacture complex shapes / components
   • Cheap
   • wide range of colours and transparencies
   • relatively low in strength and dimensional stability
   • coefficient of thermal expansion and has low heat resistance
   • Plastics with high performance are expensive
   • Softer than metals and are likely to be effect to deformation under load
   • Brittle at low temperature and flammable
   • Add-ons ( substances) are used to improve the mechanical properties, to reduce the cost and improve moldability and impact colour
   • Organic polymers (1866)
     • Made from carbon and hydrogen backbone
   • Inorganic polymers (1866)
     • Made from silicon/ phosporous backbone
   • Polymers properties depend on the chemicals they are made from and the conditions in which they are made
     • For example- there are two main types of poly(ethane) Low Density Poly Ethane (LDPE) and High Density poly Ethane ( HDPE). LDPE is weaker compare to HDPE and it becomes softer at low temperatures.
   • Modern polymers are used for.........
     • filling for teeth
     • waterproof coating for fabrics ( outdoor clothing)
     • Dressing for cuts
     • New packaging materials
     • Hydrogels for soft contact lenses and disposable nappy liners
     • Smart materials for example shape memory polymers for shrink-wrap packaging
   • Condensation Polymers- some polymers are made using condensation polymerisation.
     • In condensation polymerisation, a small molecule is created as a by product each time a bond is created between two monomers. this small molecule is usually water
   • Intramolecular and Intermolecular bonding in polymers
     • • Polyethylene-Intramoleculars bonding (Covalent)
       • Polyethylene - Intermolecular bonding (van der waals)
       • The whites are carbon
       • The blacks are hydrogens
     • • polyvinylchloride- Intramoleculars bonding (covalent)
       • polyvinychloride- Intermoleculars bonding (hydrogen/ van der waals)
       • Green- chloride
       • Whites- carbon
       • Blacks- Hydrogen
   • Polymers plus Additives
     • additives- a substance added to something in small quantities to either improve or save it.
     • Antistatic Agents- Attracts moisture from air to plastic surface. This improves surface conductivity
       • moisture- water or a liquid spread(diffuse) in small quantity as vapour ( a substance diffused or released in the air  )
     • Coupling agents- Improves the bonding of the plastic
     • Fillers- fillers such as flakes/short fibre or inorganic materials
     • Stabilizers- stops plastics deteriorating due to environmental factors
       • deteriorating- getting worse 
     • Pigments- The colour to the plastic
     • Flame Retardants- organic materials-flammable additives comprising CL, BR etc metallic salts reduces combustion
     • Lubricant -when lubricant is added it reduces viscocity and it improves forming characteristics
       • Viscocity- Thick, sticky and semi-fluid in density/ firmness or solidity due to its inside friction
     • Reinforcements- increases the strength and stiffness of a polymer especially fibre of glass
     • Plasticizers have low molecular weight and this changes the properties and forming characteristics ( flexible grades of PVC)
       • PVC- polyvinylchloride
   • Polymers Nomenclature
     • Thermosets (crossed linked chains)
       • Thermosetting plastics materials cure through the addition of energy, to a stronger form.THEY DO NOT HAVE Tg(BAKELITE)
     • Thermoplastics (linear or branched chains)
       • Certain polymers temperature raises above Tg and Tm. They are easier to mold and shape into any desired part or component for example PVC, Polythylene
     • Elastomers
       • They have a wide range of applications such as high friction and non-skid surfaces , protection against corrosion and abrasion, electrical insulation shock and vibration insulation
   • NEW POLYMERS
     • POLYIMIDES AND POLYBENZIMIDAZOLE
       • Polyehtherimide (PEI)
       • Thermoplastic Polyimide (PI)
       • Polyamideimide
     • POLYARYLETHERS AND POLYACRYTHIOETHERS
       • Polyarlethersulphone (PES)
       • Polyphenylene Suphide (PPS)
       • Polyehtherketones (PEEK)
     • FLOUROPOLYMERS
       • Flourinated Ethylene Propylene (FEP)
       • Perfluoroalkoxy (PFA)

5. COMPOSITE MATERIALS

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