1.1 Materials and their applications Flashcards
Compressive strength
Mechanical property
the ability to withstand being crushed or shortened by pushing forces
Tensile strength
Mechanical property
the ability to resist stretching or pulling forces
bending strength
Mechanical property
the ability to resist forces that may bend the material
Shear strength
Mechanical property
the ability to resist sliding forces on a parallel plane
Torsional strength
Mechanical property
the ability to withstand twisting forces from applied torque or torsion
Hardness
Mechanical property
the ability to resist abrasive wear such as scratching, surface indentation or cutting
Toughness
Mechanical property
the ability to absorb impact force without fracture
Plasticity
Mechanical property
the ability to be permanently deformed and retain the deformed shape
Ductility
Mechanical property
the ability to draw out under tension, reducing the cross-sectional area without cracking
Malleability
Mechanical property
the ability to withstand deformation by compression without cracking, increases with a rise of temperature
Elasticity
Mechanical property
the ability to be deformed and then return to the original state when the force is removed
Electrical conductor
Physical property
allows the flow of electrical current though the material
Electrical insulator
Physical property
does not allow the flow of electricity through the material
Thermal conductor
Physical property
allows the transfer of heat energy through the material
Thermal insulator
Physical property
prevents the transfer of heat through the material
Thermal expansion
Physical property
the increase in material volume in response to heat input
Opaque
Physical property
prevents light from travelling through
Translucent
Physical property
allows light through but diffuses the light so the object appears blurred
Transparent
Physical property
Allows the light to pass through easily which means you can see clearly though the material
Density
Physical property
the mass of the material in a standard volume of space
Fusibility
Physical property
the ability of the material to be fused or converted from a solid to a liquid or molten state, usually by heat
Magnetism
Physical property
the natural force between objects that causes the material to attract iron or steels
Corrosion/degradation resistance
Physical property
the ability of the material to withstand environmental attack and decay
Ferrous metal
a metal containing mostly iron and carbon
ferrous metals are magnetic and will rust
e.g. low and medium carbon steel, cast iron
Non-ferrous metal
a metal that does not contain iron
not magnetic and will not rust
e.g. aluminium, copper, zinc
Alloy
a metal made of two or more metals or combining two or more elements, one of which must be metal
can also be classified as ferrous or non-ferrous alloys
ferrous alloys: stainless steel
non-ferrous alloys: bronze
Hardwood
a wood from a broad leafed tree
these trees are generally slow growing and lose their leaves in autumn
BBB MOAT
Softwood
a wood from a coniferous tree
these trees are generally fast growing and evergreen
DR SPRCL
Manufactured board
a man made wood based composite material
manufactured boards are available in much larger sizes than solid wood
e.g. plywood, chipboard, mdf
Thermoplastic
a material which can be repeatedly reheated and reshaped allowing it to be recycled after its initial use
e.g. LDPE, PP, HIPS
Thermosetting polymer
a material which when heated undergoes a chemical change whereby the molecules form rigid cross links
e.g. UF, MF, epoxy resin
Elastomer
a material which at room temperature can be deformed under pressure and then upon release of the pressure will return to its original shape
e.g. natural rubber, silicon, neoprene
Papers and boards
e.g. layout paper, cartridge paper, laminated card
Composites
made by combining two or more different materials
e.g. CFRP, GRP, tungsten carbide
Smart materials
a material whose physical property can change in response to an input or change in the environment
e.g. SMA, thermochromic pigment, piezo electric material
Modern materials
a material development through the invention of new or improved processes
e.g. kevlar, PMC, polymorph
Tensile testing
Workshop
clamping material samples of the same length and thickness into a vice and applying a load such as weights to the unclamped end.
the less deflection under load, the more tensile strength it has
Toughness testing
Workshop
samples clamped into a vice
each sample is then hit with a hammer with the same force
tough materials absorb impact, brittle materials may bend or shatter
Hardness testing
Workshop
abrasive:
running a file over the surface of the material using the same force for each sample
indentation:
using a dot punch and hammer
material is supported underneath and the dot punch is placed onto the material surface
the dot punch is hit once by a hammer for each material sample
Ductility and malleability testing
Workshop
secure test piece in a vice
try to bend the test piece to 90 degrees
cracks or surface damage on the outside of the bend indicate a lack of ductility
cracks or surface damage on the inside of the bend indicate a lack of malleability
Corrosion testing
Workshop
materials can be placed outside in an area exposed to weather effects and left for a certain length of time
materials can be visually inspected for the surface corrosion
Conductivity testing
Workshop
electrical:
can be tested using a multimeter
thermal:
can be tested using a thermometer
Tensile testing
Industrial
a test piece is placed into a tensometer machine and held in clamps at each end
one clamp is fixed as the other moves in a worm drive gear mechanism
as the worm drive turns, the test piece is put under tension
Toughness testing
Industrial
the IZOD impact test is used
a notched test piece is held vertically in the vice of the test machine
a pendulum is released from a set position and swings to strike the test piece
Hardness testing
Industrial
Rockwell, Brinell, Vickers pyramid
Rockwell
a preload is applied to the material sample using a diamond indenter which breaks through just the surface of the material
the preload is called the datum
an additional load is then applied to the test material and held for a predetermined length of time (dwell times)
the smaller the indentation depth, the harder the material
Brinell
a hardened standard size steel ball is forced into the material surface using a pre-set load
the diameter of the indent in the surface is measured
the smaller the indent, the harder the material
Vickers pyramid
used to test very hard materials
this test uses a diamond square based pyramid to indent the surface of the material
diamond is used because it will not deform under load
a microscope is used to measure the size of the indent
Ductility and malleability testing
Industrial
a bend test is used to determine how well a material can withstand cracking during one continuous bend
a test piece is placed into a bending machine and held, supported at the ends
a mandrel loads the test piece to the centre and bends to the predetermined angle
cracks on the outer bend = indicate level of ductility
cracks on inside of bend = indicate level of malleability
Non destructive testing
ultrasonic
xray
electrical conductivity
