Composite Materials Flashcards
What is a composite ?
Composites are a combination of 2 or more different materials that are bonded together and they are made in order to enhance the properties of each material
What 2 things need to be added to make a composite ?
Fibre / Filament reinforcement + Matrix = Composite
What are the properties of a fibre / filament reinforcement ?
- High strength
- High stiffness
- Low density
What are the properties of the matrix ?
- Good shear properties
- Low density
What are the properties of composites ?
Composite materials have enhanced properties
These fall into 2 categories;
- physical
- mechanical
- enhanced
What are mechanical properties ?
Mechanical properties are related to different forms of strength
What are physical properties ?
Physical properties relate to size, weight and different behaviours
What are some physical / mechanical properties of composites ?
- Ability to be moulded into a variety of 3D forms
- Enhancement of physical and / or mechanical properties
- Ease of manufacture for some uses against traditional materials
- improved product performance - because of the enhanced properties
What are some examples of mechanical properties ?
- tensile and compressive strength
- stiffness and toughness
- plasticity and elasticity
- ductility and malleability
Give some examples of physical properties
- Mass, weight and volume
- density and hardness
- electrical conductivity and resistivity
- thermal conductivity and expansion
What are all the composites that you need to know ?
- Carbon Fibre reinforced plastic ( CFRP )
- Glass reinforced plastic ( GRP )
- Tungsten carbide
- Aluminium Composite board
- Concrete, including reinforced concrete
- Fibre cement
- Engineered wood - e.g. glulam ( glued laminated timber )
What is a cermet ?
A cermet is a composite made from ceramic and metal
What is tungsten carbide ?
Tungsten carbide is a cermet or its an alloy of tungsten and carbon ( carbon is the ceramic and tungsten is the metal )
Its usually mixed with a binder which is most commonly Cobalt
What are the properties of Tungsten Carbide ?
- its grey in colour
- its extremely hard, rigid and impact resistant
- Its 100x harder than steel so to cut it or sharpen it you would need diamonds
What is tungsten carbide used for ?
Tungsten carbide retains its properties even at extreme temps
- This makes it ideal for use in high speed cutting tools which get hot due to friction
- Commonly used for router/drill bits, premium kitchen knifes, surgical instruments and even jewellery
- Tungsten carbide can be formed into complex 3D shapes through the process of splintering
What are carbon fibres ?
They are several times thinner than human hair, lightweight with high tensile strength
Fibres are woven into a fabric - the more complex the weave, the more durable the material will be
Carbon fibre fabric is built up in layers and formed in moulds to make complex shapes
How do you make Carbon fibre reinforced plastic ( CFRP ) ?
Layers of carbon fibre are impregnated with a plastic resin to form carbon fibre reinforced plastic
What are the physical properties of CFRP ?
- corrosion and chemical resistant
- lightweight
- stable in hot conditions
What are the mechanical properties of CFRP ?
- Tough and hardwearing
- Good tensile strength
Whats CFRP used for ?
Used for high-tech bike frames and sports equipment, racing cars, crash helmets and prosthetics
How is glass reinforced plastic ( GRP ) made ?
Thermosetting plastics such as polyester or epoxy resin are combined with fibres made of glass to make GRP
Glass fibres are strong in tension with little compressive strength
Conversely, resins are strong in compression but weak in tension
What is GRP commonly known as ?
Fibreglass
What are the physical properties of GRP ?
- lightweight
- resistant to corrosion and UV
- highly durable
- water tight
What are the mechanical properties of GRP ?
- high compressive strength
- high tensile strength
What’s cheaper - GRP or CFRP ?
GRP is far cheaper than cheaper than CFRP
What’s GRP used for ?
GRP is used to make complex 3D shapes such as boats or car body panels and sculptures
What is aluminium composite board ?
A composite sheet material combining a polymer core ( usually polyethylene ) faced with a thin sheet of aluminium
What’s aluminium composite board used for ?
Used for signage and architectural cladding and wall panels
What are the physical properties of aluminium composite board ?
- durable
- lightweight
- resistant to corrosion
- really flat
- strong
What are the mechanical properties of aluminium composite board ?
- available in a wide range of colours and finishes
- perfect substrate for high quality UV printing
How does aluminium composite board compare to polymers ?
- Compared to polymers, aluminium composite board wont expand and contract in extreme weather
- panels will not warp or wrinkle over time
- its a versatile means of creating a building façade that would be physically impractical with other materials
What is fibre cement ?
It is a composite building material used for cladding, roofing and building facades because of its strength and durability
What is fibre cement made from ?
Originally made from cement and highly toxic asbestos fibres - cellulose and synthetic fibres are now used instead
What are the physical properties of fibre cement ?
- durable
- lightweight
- resistant to rust, weathering and chemical / insect attacks
- vapour permeable - reduces any condensation in buildings
- great thermal and noise insulator
What are the mechanical properties of fibre cement ?
- flexural strength
- tensile strength
- ductility
- crack resistance
Why is fibre cement good for aesthetics ?
The smooth finish of fibre cement is ideal for creating a sleek, minimalist design
What do some fibre cement products imitate ?
Some fibre cement products are textured to imitate wood grain for a more traditional aesthetic
What are the stock forms of fibre cement ?
Sold in large sheets, slates or boards
Is fibre cement easy to work with ?
Large sheets are quick and easy to work with and the gaps between the sheets can be used to make interesting patterns
What is concrete ?
Concrete is one of the most common building materials on earth
What is concrete used in ?
Used in making buildings, bridges, dams, tunnels, sewage systems, pavements and roads
How is concrete made ?
Its a composite made from a mix of several ingredients, the proportions of which can vary depending on the material properties required
What are the properties of concrete ?
- heavy
- durable
- not weakened by moisture, mould or pests
- good thermal insulator - reduces heating and cooling costs in a building
- fire resistant - can be polished to create an industrial look
What are the pros of concrete ?
- low cost
- low maintenance
- can be cast into moulds for vertical structures or poured to create flooring and paving
Very little concrete is traded internationally - why ?
Very little concrete is traded internationally because companies would rather get it locally sourced which reduces CO2
What is reinforced concrete ( RC ) ?
Reinforced concrete is a composite material in which concretes relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength and ductility
Where is steel reinforced concrete used ?
Steel reinforced concrete is used in high-rise buildings, bridges and multi-storey car parks
Why is reinforced concrete better than normal concrete ?
High winds and earthquakes put concrete under strain, causing structures to fracture and collapse
Steel reinforced concrete has improved strength under tension and will last longer
Also with reinforced concrete you can build taller, stronger and more complex concrete forms.
What is engineered wood ( manufactured board ) ?
These are wood-based composites designed to enhance the properties of natural timber
What is glulam ?
Glued laminated timber
How is engineered wood made ?
They are manufactured by binding or fixing the strands, particles, fibres or veneers or boards of wood, together with adhesives or other forms of fixation to form composite materials
In short, all manufacturing boards combine wood sheets, chips or particles with a bonding agent
How is engineered flooring made ?
Engineered flooring combines a plywood or HDF base with a hardwood veneer - this offers stability, durability and a natural aesthetic
What is often added to particle boards ( Chipboard ) ?
Melamine Formaldehyde ( MF ) is often added to chipboard to achieve a hardwearing finish
What are glulam beams made from and what are they used for ?
Glulam beams are made from layers of laminated timber formed around a mould
Glulam can be used as an alternative to steel to make beams, bridges and archways
