PHYSICAL PROPERTIES Flashcards
what is a physical property
a characteristic of a material that can be measured or observed without changing its chemical structure
what is a working property
how a material responds when it is manipulated or worked
examples of physical properties
absorbency
density
electrical conductivity
thermal conductivity
fusibility
what is density
the mass per unit volume of any material. how solid a material is
what is fusibility
the ability of a material to be converted from a solid to a fluid state by heat and combined with another material
ductility definition
the ability of a material to be stretched or drawn or pulled without breaking
-> ability to be drawn into a wire
elasticity definition
the ability of a material to return to its original shape after stretching or compressions
hardness definition
ability to withstand impact, wear, abrasion and indentation
malleability definition
ability to be bend and shaped without cracking or splitting
strength definition
ability to withstand a force such as pressure, compression, tension or shear
toughness definition
ability to absorb shock or impact force without fracturing
go over properties and uses of paper, card and board
slay
what are hard woods and give examples
- woods that come from deciduous trees (trees that loses its leaves in a particular season)
examples:
ash, mahogany, oak, beech, balsa
two differences between hardwood and softwood
- hardwood comes from deciduous trees, softwood comes from coniferous trees
- deciduous trees are slower growing, which makes wood denser
what are softwoods and give examples
wood that comes from a coniferous tree (doesn’t lose it’s leaves and usually bears needles and cones)
examples:
pine, spruce, larch
Examples of manufactured timbers
Plywood
Chipboard
Medium density fibreboard (MDF)
advantages of using natural timber
- aesthetic appeal : attractive grain and texture patterns
- non toxic: can be used in furniture and children’s toys
disadvantages of using natural timber
- expensive, especially hardwoods
- requires regular maintenance such as sealing, oiling etc to protect it from external factors such as sunlight and water
- stock size is limited, they come in planks
advantages of manufactured timber
- available in multiple large board sizes, reducing the number of joins
- cheaper than natural timber
- easily cut
- can be easily laminated to apply a wide range of finishes
disadvantages of manufactured board
- dense, making them very heavy n sheets
- edges are difficult to finish because they don’t have a natural end grain
- not as attractive/appealing as natural timbers
what is a ferrous metal
a metal which contains iron and have high tensile strength and durability
examples of ferrous metals and their uses
- cast iron metal: manhole covers: hard but brittle and resists deformation and rust
- low carbon/mild steel: steel building frames: tough and ductile. rusts easily if not protected
- high carbon steel: hard but brittle, resists abrasion and retains its shape. used in tools, blades and scissors
explain two factors that make a metal an expensive material to obtain
- mining is very dangerous and often very remote
- mining machinery is expensive to buy and operate
- techniques often use dynamite, destroying the earth’s surface
what are non ferrous metals
metals that are a group of pure metals and do not contain iron
properties of non ferrous metals
- non magnetic so it’s used for wiring and electronics
- higher resistance to rust but can corrode or oxidise
- commonly used externally for guttering , pipes and road signs
what is an alloy
alloys are mixtures of at least one pure metal and another element to improve working properties or aesthetics
examples of alloys
high speed steel
stainless steel
brass
bronze
advantages of alloys over pure metals
alloys are generally harder and denser thana most pure metals
alloys often have better corrosion resistance than a pure metal
- easier to manipulate it into different forms
what is a thermoforming polymer
a polymer when heated, can change it’s shape again
what is a thermosetting polymer
a polymer which when is heated, CANNOT be reshaped again
comparison of thermoforming and thermosetting
thermoforming: more flexible
thermosetting: resistant to higher temperatures, burn when heated, harder, more brittle, good insulators and have a higher chemical resistance
examples of thermoforming plastics
- HDPE
- poly propylene
- HIPS
- Acrylic
- PVC: poly vinyl chloride
examples of thermosetting plastics
-polyester resin
- urea formaldehyde
- melamine formaldehyde
- epoxy resin
