Material Properties Flashcards
malleability
the ability of a material to withstand deformation by compression (before it shows sign of cracking) e.g copper — malleability increases with temp. and therefore metals which need to be bent, rolled or extruded, are heated first
ductility
the ability of a material to be drawn out, can be deformed under tensile stress, (ability to be stretched into a wire) e.g copper`
toughness
the ability of a material to withstand sudden impact without fracture (can also refer to withstanding bending), opposite to brittle
elasticity
the ability of a material to flex and bend when forces are applied and to regain normal shape and size when those forces are removed
plasticity
the ability of a material to be permanently changed in shape by external forces e.g hammer blows, pressure, without cracking, metals and thermoplastic polymers tend to generally be more plastic when heated
hardness
the ability of a material to resist abrasive wear, indentation or formation, important property of cutting tools e.g drills
durability
the ability of a material to withstand wear and teach, weathering and the deterioration or corrosion this may cause, weathering can results in mechanical weakening
stability
the ability of a material to resist changes in size and shape due to its environment, e.g timber tends to warp and rot due to changes in humidity, metals and some plastics deform subject to continual stress: these processes are known as ‘creep’
strength
the ability of a material to withstand force without breaking or permanently bending
tensile strength
the ability of a material to resit stretching or pulling forces
compressive strength
the ability of a material to withstand pushing forces which attempt to crush or shorten the material
bending strength
the ability of a material to withstand forces with attempt to bend the material
shear strength
the ability of a material to resist sliding forces acting against each other
torsional strength
the ability of a material to withstand twisting forces under torsion or torque
magnetism
a property possessed by many elements, and is the product of the orientation of electrons about their atoms, only a few elements are strongly magnetic
fusibility
the ability of a material to change into a molten or liquid state when heated to a certain temperature, i.e melting point, varies between materials but is essential to processes such as casting welding and soldering
density
defined as mass per unit volume — relative density is the ratio of the density of the substance to that of pure water at a temperature of 4 degrees celsius
electrical conductivity
all materials resist the flow of electricity to some extent - conductors offer a very low resistance to the flow of an electric current, e.g metals like copper, silver and gold
electrical insulators
offer a high resistance to the flow of electricity — non-metals are generally good insulators but vary individually e.g ceramics, glass, nylon, PVC
semi-conductors
slowed electric current to flow under certain conditions, e.g silicon and germanium in their pure state are poor conductors, but their electrical resistance can be altered by the addition of impurities
meaning of thermal properties
the way in which a material reacts to heat
thermal conductivity
relates to how heat travels through the material, measured in watts per metre per degree Celsius, copper + aluminium have high thermal conductivity
thermal insulators
relates to materials with low value thermal conductivity, generally non-metals — used to prevent heat gains and losses e.g pan handles, loft insulation
thermal expansion
materials generally expand when they get hot and shrink upon cooling, control mechanisms also used this effect e.g car thermostats, automatic kettles
meaning of optical properties
refers to how materials react to light and heat by reflection, radiation and absorption
opaque
does not allow light to pass through e.g house brick
translucent
allows some light to pass through e.g photocopy paper
transparent
allows light to pass through e.g glass
