Multiple choice Flashcards
What is the Weideman Franz Law
Thermal conductivity is linearly related to electric resistivity. The lower the electric resistivity the higher the thermal conductivity
What determines the density of a material?
Atomic weight, Atomic size, Packing density
What determines the modulus of a material?
Interatomic bonds and packing density
What is young modulus
The ability the withstand changes in length when under tension or compression
What are the three types of bonding
Covalent, ionic and van de warl
How to change the modulus?
Change interatomic bonds (inorganic vs organic materials)
Architecture
Density definition and units
mass over volume
Modulus of Steel
207GPA
Three ways to make a metal stronger
Solid solution hardening, precipitation hardening, work hardening
What is quenching and tempering
Heat treating techniques and tempering. learn about this
What is a thermoplastic
You can heat it up and reheat. Has comparatively poor thermal properties. Nylonms, Polyethelene, ABS, PET, polypropylene
What does abs stand for?
Acrylonitrile Butadiene Styrene
Thermosetting plastics?
Unsaturated polyester, polymerise to form a three dimensional network that cannot be melted
How are plastic bags made?
Extrusion film blowing
How is a pole volt made
Filament winding
What are plastic bottles made from? and why?
Polyethalene terapthalen PET, because the carbon dioxide cannot escape from it. Stretching it in the blow moulding process aligns the crystals and makes it crystalline
Tyres have a butile inner liner why?
To keep air in
How is a shampoo bottle made
Extrusion blow moulding process
How to make flat sheet of polymer
extrusion
What does anisotropic mean?
It means that the strength is only in one direction (important for composites)
What do the conditions for thermosetting composites need to be?
The resin for the matrix needs to be low viscosity. Resin needs to flow and combine with solid fibres easily. Fibres are available in different forms. Matrix undergoes a curing reaction. Unsaturated polyesters, vinyl esters, epoxies, furanes and urethane acrylates
What is continuous roving in glass fibres?
cheap and consists of thousands of fibres that can be aligned
What are chopped glass fibre mats?
For low cost random fibre composites
What are woven fabrics?
High volume fraction and better properties?
What are the three ways to harden metals?
- SOLID SOLUTION STRENGTHENING 2. Precipitate or dispersion hardening. 3. Work- hardening
What is an interstitial alloy?
Where the solute fits into the spaces between the atoms of the crystal
What is a substitutional alloy?
The solute replaces atoms of the solvent crystal
What is hardness
resist abrasion, wear, scratching, penetration
What is toughness?
Toughness is the measure of the amount of the load or force that a material can absorb before fracture
What is toughness?
Toughness is the measure of the amount of the load or force that a material can absorb before fracture j/m squared
What is specific modulus?
Modulus/Density
What does cold working do to a metal?
Makes it stiff hard and strong
What is Modulus?
Modulus is stress/strain and can be young modulus, shear modulus or bulk modulus (when loaded from all sides)
What is tri-axial compression?
Also known as hydrostatic compression, it involves no shear but can result in overall volume change
What is tri-axial compression?
Also known as hydrostatic compression, it involves no shear but can result in overall volume change. Shear stresses on some planes result in plastic deformation forcing it into the desired shape.
What is annealing?
Where you heat a metal up to a certain temperature and then cool it slowly
What are good materials for seals? ceramics
Alumina, silicon carbide, silicon nitride
What are good materials for seals? ceramics
Alumina (aluminium oxide), silicon carbide, silicon nitride
What would you make a turbine stator from?
Silicon carbide, silicon nitride
What do you use to make a heat sink
Aluminium Nitride because it doesn’t conduct electricity
What are the three types of ceramics?
Structural, electrical and biological
What are the key properties of Furnace insulation
Low thermal conductivity, High temperature stability
Key properties of miniature capacitors
High polarisability, high dielectric constant, low dielectric loss
Key properties of miniature capacitors and materials
High polarisability, high dielectric constant, low dielectric loss, titanates
What would you make a ball bearing from
Silicon Nitrate for high temperature and high load
What would you make a transducer from?
Lead Zirconate Titronate
For grinding materials what do you use? and for high temperature nozzles
A ceramic
What are the three welding processes
Electron Beam welding, Gas-tungsten arc welding, Shielded metal arc welding.
What are the three points on the magic triangle for tyre design?
Rolling resistance, wear resistance, wet traction.
What is phase lag?
It is the measure of the phase difference between the applied stress and the measured strain
What should be maximised for light tie rod?
stress/density
Disadvantages when using resin transfer moulding
Firbe movment results in lower strength and stiffness than contact moulding
A full life cycle analysis can reveal which element of a specific product’s life has the greatest environmental impact. Using the specific example of a 2 litre PET bottle used to package and transport water from France to the UK, which of the following life phases will consume the greatest amount of energy and consequently produce the greatest amount of CO2?
The production of the material
Which of the following statements about the electrical resistivity of copper are true?
The electrical resistivity increases by adding a small amount of an alloying
element such as nickel.
Which of the following processing facilities are most often used to recycle scrap steel into new steel products?
a. Blast furnace
electric arc furnace
Which of the following is the correct expression used to calculate the fracture toughness KC of a material? In this equation c is the crack length, Y is a dimensionless constant that depends upon the loading configuration and c is the fracture stress.
KcYc πc
What is yield strength?
The yield strength point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning plastic behavior.
Which of the following are reasons for using powder processes to make metal components?
Unusual microstructures that cannot easily be cast can be produced.
Which of the following is present in a solid solution strengthened interstitial metal alloy?
The solute atoms fit into spaces between the solvent atoms, which distorts the
lattice.
