The Technological world (Materials, Constraints and deformations) Flashcards
What are the mechanical properties (5)
- Hardness
- Resilience
- Malleability
- Ductility
- Stiffness
- Corrosion resistance
What is hardness ?
Resist deformation when hit.
What is resilience ?
Resist shock and impact with deforming
What is malleability ?
Can be compressed without breaking.
or flattened or bent without breaking
What is ductility ?
Can be stretched without breaking
What is stiffness ?
Can maintain shape when put through many constraints
What is corrosion resistance ?
Can resist smoke, salt and chemical properties.
What are the types of constraints ? (5)
- Compression
- Tension
- Torsion
- Deflection
- Shearing
What is compression ?
Crushing the material
What is tension ?
Stretching the material
What is Torsion ?
Twist the material
What is Deflection ?
Bend the material
What is Shearing ?
Cutting the object
What are the types of deformations ? (3)
- Elastic
- Plastic
- Fracture
What is the plastic deformation ?
Permanent change in shape of object
What is the elastic deformation ?
Constraints that leads to temporarily change in shape, when constraint is removed the shape returns to its original shape
What are some properties of plastic ?
-Durable
-Cheap (General)
-Light
-Sometimes transparent
others
What are plastic made from ?
Fossil fuels
What are fossil fuels made from ? (2)
- Oil
- Gas
What is positive about plastic degradation ?
The process is slow, but irreversible
What are signs of degradation ? (2)
- Cracking
- Change in color
What are the types of plastic ? (2)
- Thermoplastics
- Thermosetting
What are Thermoplastics ?
Plastic that becomes soft when heated so it can be molded or remolded and then hardens. Usually can recycled
What are Thermosetting plastics ?
Plastic that remains permanently hard even when heated. once they are hardened the shape cannot be changed. Cant be recycleed
How are Thermosetting plastics made ?
They are made by adding monomers to a mold, and
How can you protect against penetration of liquid ?
By adding water proof coating
How can you protect against oxidation ?
By adding anti oxidants
How can you protect against ultraviolet rays ?
By adding dark pigments to absorb UV rays
How are ceramics formed ? Explain the process
When inorganic compounds are heated, the water evaporates and the bonds between the compounds are rearranged to form ceramics
How is low electrical conductivity used ?
They are used as insulators
How is hardness used ?
Used in building material
How is heat resistance and low thermal conductivity used ?
Kitchen appliances
How is resistance to corrosion used ?
Used in ducts for fumes and
water coolant in your car
How is resilient used ?
Used in engines.
What are composites ?
Many materials combines to get a mix of properties ?
What are matrix composites like ?
They are like skeletons
What are reinforcement composites like ?
They are like muscles and fat
What is fibreglass ? what are its properties ?
Made of glass (ceramics) in form of fibers
- Stiffness
- Corrosion resistance
What is aramid fibers reinforcement ? what are its properties ?
Known as kelvar
- Low density
- Resilience
What are carbon fibers reinforcement ? what are its properties ?
Obtained by carbonizing polymers
- Stiffness
- Low density
- Electrical conductivity
What are plastic matrix ? what are its properties ?
They are used as matrices, they are referred to as resins
- Durability
- Lightness
- Resilience
- Low cost
What are metallic matrix ? what are its properties ?
made from metals or alloys
- Ductility
- conductivity
- stiffness
What are ceramic matrix ? what are its properties ?
Made from ceramics, often glass
- Durability
- Heat resistance
What does plastic act as matrix or reinforcement ?
Matrix
What does fibreglass act as matrix or reinforcement ?
Reinforcement
What type of degradation does metals and alloys face ? and why ?
They can oxidise (rust) or chemically alter if they are exposed to acid, rain, salt, oxygen
What are 2 types of protection for metals and alloys against degradation ? and why ?
-Coating
coat of paint because it block oxygen
-Heat treatments :(hardening and tempering)
What are some characteristics of decidous trees ?
loose leaves, hardwood
What are some characteristics of conifers trees ?
needles , evergreen , softwood
