COMPOSITES Flashcards
What are the three categroies of composite materials
Fibre based
- reinforced with fibres
- GRP (glass reinforced plastic)
- CFRP (carbon fibre reinforced plastic)
Particle based
- reinforced with particles
- concrete
- cermets
Sheet based
- boards made from wood pulp, chips or layers
- chipboard, contiboard, MDF, plywood, stirling board
Define a composite material
A material that is created using a combination of two or more materials which combines the cahracteristics of both, enhancing the composite matrials properties and functions, which cannot be gained from a singular material.
Examples of fibre reinforced composites
Elastomers
Concrete
Polymers
Fibre reinforced platsic
Glass reinforced plastic
Carbon fibres
Kevlar
Plastic laminates
Examples of Particle reinforced composites
Concretes
Tarmac
Cermets
Titanium carbide
Tungsten carbide
Filiament reinforced
Ceramics
Examples of sheet based composites
Plywood
Blockboard
What are the charcateristics of fibre based composites
Good strength to weight ratio
Resistance to corrosion
Good fatigue resistance
Low thermal expansion
What are the characteristics of particle based composites
high strength
good stability
uniform structure ensuring consitent strength
gernerally free from surface defects
How is glass fibre prodcued
- spun to produce a fibre which is coated to aid bonding to the resin
- the fibres are available in a variety of thicknesses
- the polyester resin used is quite brittle on its own and the galss fibres are useless without resin
- a mould is required for GRP but these can be produced cheaply
- glass fibre shapes are made by laying up
- mould
- wax applied
- gel coat applied to provide colour
- fibregalss, resin + catalyst applied in layers and rolled out
- after curing the part is removed from mould and trimmed
Example of a product glass fibre is used for
Used for helicopter rotor blades and wind turbine blades
- has antislip safety
- can be produced fire retardant
- chemical resistant
- high strength to weight ratio
What is CFRP
Carbon reinforced polymer
- used as matting for F1 car bodies
- tennis raquets
- carbon fibres are woven into a matt which is cut out into shape (this gives carbon fibres its distinct look)
What is kevlar
A mixture of aromatic and aromid (nylon-like) molecules melted together and spun into fibres
- this material has a very high strength to weight ratio
- it is 5x stronger than steel but half the desnity of fibre class
- impact resistant
- used for body protection, sports equipment, gloves for use with galss and sheet metal
What is concrete
Concrete is made up of materials known as aggregates (sand and cements)
- concrete can be reinforced with galss fibres to make GRC
- this allows it to cast to more complex and delicate structures as the galss fibres replace the need for aggregate
What is a cermet
A mixture of both metal and cermaic particles.
Eg. Tungsten carbide = cermaic tungsten mixed with metal colbalt.
- this is used to cut tools as it keeps its edge well
- Aluminium oxide and colbalt used in jet engines
= high temp resistant, shock absorbant and strong
