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