All Materials

Properties of wood

properties vary with wood type
light, flexible, good insulator

Hardwood

Usually deciduous, loses leaves, harder, takes longer to grow, more expensive, broad leaves

Hardwood example

oak, beech, mahogany, holly

Softwood

usually coniferous, keeps leaves, grow faster, softer, easier to work with, less expensive, thin leaves, less heavy

Manufactured boards

man-made boards made from processed wood glued together 

MDF

medium density fibreboard
made from particles of wood compressed and glued together

MDF advantages + disadvantages

• recycles materials, can be used to make larger boards

• dust can be harmful to lungs, can be carcinogenic

Plywood

made from thin strips of wood called venirs stuck together with
alternating grain for strength

Plywood advantages + disadvantages

• very durable, can be made into large sheets, no natural defects

• expensive, potential for warping but less likely than regular wood

Chipboard

made from large particles of wood. Often covered with a venir as
the front is unattractive

Chipboard advantages and disadvantages

• recycles materials, can be used to make larger boards

• not aesthetically pleasing, not very durable

Disadvantages with wood:

• wet rot

• dry rot

• wood worm

• splits

• shrinkage

• warping

Properties of metals

dense, good conductor, malleable, ductile

How to prevent ferrous metals from rusting?

painting, galvanising (coating in zinc)

Compression moulding

• plastic or metal is put between two halves of a mould and compressed into the desired shape

• ejector pin pushes out the final mould

Biodegradable plastic

cornstarch + hemp, renewable

Thermosetting plastic

can only be heated and moulded once
bakelite, melamine

Thermoplastic

can be re-heated and moulded many times
acrylic, PET polyethylene terephthalate, HDPE high-density polyethylene

Nylon - Properties + Uses

• tough + durable

• self lubricating

  • mechanical parts, clothing + bags

Acrylic - Properties + Uses

• stiff + hard

• scratches easily

  • DIY projects, storage boxes

Polystyrene - Properties + Uses

• light + brittle

• good insulator

  • toys, packaging containers

High Impact Polystyrene (HIPS)

• impact resistant

• good insulator

  • housing, tarp covers

Expanded polystyrene

• light

• durable + shock absorbent

  • packaging, helmets, shoes

Polyethylene teraphthalate (PET)

• light

• cheap

• soft

  • bottles, polyesters

Polyvinylchloride (PVC)

• rigid

• resistent to chemicals

  • water pipes, credit cards

Epoxy resin

• good insulator

• hard + brittle

  • electrical casing, adhesive

Melamine

• stiff

• stain resistant

  • work surfaces, electrical insulator

Injection moulding

• plastic pellets are fed into the screw
  through the hopper, they are then heated, pushed forward by the crew and injected into a cast of the item to be made.

• the mould casing is removed and the plastic mould is trimmed

• can be used on metals and glass also.

Vacuum forming

• plastic (polystyrene) is melted heated and lower onto the mould

• the plastic is sucked on to a mould using a vacuum.

• Holes are put in the mould to allow plastic to form easily overthe mould.

• once cooled the plastic is removed and trimmed

Blow moulding

In blow moulding plastic is formed by
blowing plastic into a solid mould. (Similar
to blowing up a balloon)

Strip heating

In strip heating a thermoplastic is heated
along a line and bent using a piece of
wood to form an angle.

Polymer

large number of repeating small molecules bonded together in a chain

What is the difference between ferrous and non-ferrous metals + Examples?

Ferrous metals

• contains iron

• attracted to magnets

• rusts

• steel

Non-ferrous metals

• does not contain iron

• is not attracted to magnets

• do not corrode as quickly, and do not rust

• gold

Ceramics

inorganic, non-metallic materials that can be shaped and then heated and cooled to make hard, heat resistant objects

Characteristics of ceramics

• hard

• brittle

• high melting point

• chemically resistant

• poor conductors

Composites

• Materials made of a mixture two or more different materials, in order to combine the uses of the properties of both materials,

• the materials are not chemically combined but mixed such as concrete (sand, stones + cement)

Semi-permanent joining example

screws, bolds, nails

Permanent joining example

gluing, welding, soldering

Example of wood joints

butt joint - simple, no interlocking parts

lap joint - overlapping wood

dowel joint - circular peg reinforces

biscuit joint - biscuit shaped wood instead of dowel

finger/comb joint - series of interlocking rectangular cuts

dovetail joint - interlocking piece shaped like a dove tail not rectangular

halving joint - two square half grooves cut into wood, piece lay flush with eachother

Smart materials

respond to changes in their environment in controlled ways

Thermochromic material

changes colour with temperature

Photochromic

changes colour with light

Self-healing

can fill scratched or cracks that come from wear and tear

Hardness

resistance to scratching

Toughness

resistance to breaking

Ductility

can be stretched out into wires

Malleability

can be moulded into various shapes

Sonorous

has a bell sound when struck

Lustrous

shiny

What is corrosion?

the deterioration of a materials as a result of a chemical reaction with its environment

eg: iron in water reacts with oxygen to form iron oxide/rust

What is the difference between an alloy and a composite?

An alloy is a combination of two different metals bonded together to form a new product with different properties

A composite is a mixture of different substances which utilises both their useful properties

What is Brass, Solder, Steel + Bronze made up of?

Copper + Zinc = Brass

Lead + Tin = Solder

Iron + Carbon = Steel

Copper + Tin = Bronze

How can wood be preserved?

Coating with oil, perservative or paint

Examples of softwoods

pine, fir, spruce

Advantages of manufactured boards

• flat

• large sheets

• cheap (except plywood is expensive)

• no knots

• let likely to warp or rot

Disadvantages of manufactured boards

• not as aesthetically pleasing

• contains many chemicals

• must be cut with facemasks worn

• higher embodied energy

What can be used to make sports equipment or stairs flooring + why?

Ash

pliable and elastic

What can be used to make kitchen tables or skirting boards?

oak

aesthetically pleasing, hard, strong

What can be used to make worktops + kitchen presses?

chipboard

cheap, but requires a veneer

What can be used to make furniture?

pine

cheap, easily available

What is glulam made up of?

AKA glued laminate

a number of layers of timber bonded with durable, moisture resistant, structural adhesive

What is plastic made up of?

synthetic polymers/plastics are made from chemicals derived from oil

What is a polymer?

a long chain molecule made by joining together many small molecules

Polypropylene

• can withstand impact

• easily moulded

• cheap

  • chairs, lab equipment

Polycarbonate

• light

• strong and hard

• coated with aluminium to give reflective appearance

  • CDs, DVDs

ABS

• high impact, strong, tough, hard

• easy to mould

• shiny surface

  • mouse, lego bricks, bike helmet

Bakelite

• high shiny

• high resistance to heat and electricity

  • saucepan handle

Melamine

• Resistant to heat and fire

• bonds to wood

  • laminated kitchen top, plastic dishes

Kevlar

• stronger and lighter than steel

• high resistance to impact

  • bullet proof vests, trampolines, tennis racket

Silicone

• flexible

• heat resistant

• non-toxic

  • sealant, adhesive, medical implant

Give an example of a natural polymer:

Latex

• highly elastic

• can be toughened

  • rubber gloves, balloons, chewing gum

What is glass made from?

fired sand and other materials

Clay ceramic

• cheap

• good insulator

• aesthetically pleasing

• hard wearing

• mouldable

  • tiles, mugs, plates, bricks

Porcelain

• stronger than clay

• can be made into thinner, finer pieces

• resistant to corrosion

  • fine tableware, false teeth

Glass

• can transmit, reflect and refract light

• smooth surface

• can be moulded

• resistant to water and chemical corrosion

• brittle

  • window panes, lenses, tableware

What is an advanced ceramic?

made by chemically combining different elements to produce materials with ceramic properties, come can also be classified as a composite

What are the properties of advanced ceramics?

• higher resistance to heat and friction

• extremely hard, some harder than diamond

Tungsten Carbide

Advanced ceramic

• extremely hard

• resistant to heat

  • cutting tools

Alumina/Aluminium oxide

Advanced ceramic

• good electrical insulator

• high mechanical strength

• high resistance to heat and friction

  • electronics eg integrated circuits, eingine parts

Silicon carbide

advanced ceramic

• extremely hard

• conducts heat

  • military armour, bricks

How can composites be made?

• bonding sheets of different materials together

• mixing fibres of one or more materials with another material which acts as the glue to bind it all together

Paper/Cardboard

• cheap

• can be recycled

• light

• easy to work with

  • writing/printing material, packaging

Concrete

• cheap

• strong

• good compressive properties

  • buildings, foundations

Plaster

• doesn’t shatter

• sets at room temperature

  • plastering walls, making casts

Laminated wood

• cheaper than solid wood

• scratch resistant

• water proof

  • floors, kitchen tops

Laminated glass

layers of glass and plastic bonded together

• high impact resistance

• plastic holds glass together if it shatters

  • windscreens, large windows

Fibreglass/Glass reinforced plastic (GRP)

• lightweight

• mouldable

• harder and stronger

• flexible

• good heat insulator

  • boat hulls, attic insulation, fishing rods

Carbon-fibre reinforced plastics

• very strong

• light

• resilient

  • fishing rod, bike frame

Plastacine

• mouldable at room temperature

• cheap

• non-toxic

  • modeling materials

Titanium metal matrix composite

• high strength

• lightweight

• low maintenance costs

• aerodynamic

  • aeroplane bodies, engines

Fabric

made by weaving thin strands of material called fibres together

What are the 2 types of fibres?

staple fibres - shorter fibres that need to be spun into yarns and tend to have a hairy appearance

filament fibres - longer fibres that give fabric a shiny appearance

Cotton

• relatively cheap

• soft to touch

• breathable

• good absorbancy

  • shirts, t-shirts, underwear, sheets

Wool

• warm

• breathable

• rough to touch

  • jumpers, suits

Silk

• very smooth

• light

• fine

• expensive

  • ties, scarves, shirts