12: Materials Flashcards
What is Elastic deformation?
Temporary change material shape, will return to original shape when constraint is removed.
What is Plastic deformation?
Permanent change in material shape
What is Fracture deformation?
Material under so much pressure that it will break
⥗⥒ ? Example
Const. Shearing, cut/tear material. Ex: Scissor on paper
⇨|
|⇦ ? Example
⇨|
Const. Deflection, bending material Ex: Gymnastics uneven bars
⇦⇨ ? Example
Const. Tension, stretching material. Ex: tug of war with rope
⇨⇦ ? Example
Const. Compression, crushing material. Ex: squeezing wet sponge
⤺
⤻ ? Example
Const. Torsion, twisting material. Ex: Wringing wet towel
What is Brittle + example
Mech. property, material breaks under force. Ex: chalk, glassware
What is Malleability + example
Mech. property, can be bent, flattened, reshaped without breaking. Ex: hockey stick, play doh
What is Ductility + example
Mech. property, can be stretched, will not return to original shape or breaking. Ex: metal
What is Elasticity + example
Mech. property, can be stretched, will return to original shape and will not break. Ex: rubber band
What is Resilience + example
Mech. property, resists shock without breaking. Ex: hammering a nail
What is Hardness + example
Mech. property, resists dents, scratches, abrasions. Ex: diamond
What is Stiffness + example
Mech. property, retains shape when subjected to various constraints. Ex: cement
What is Corrosion Resistance +. example
Property, resists corrosive material, having oxygen, to produce an oxide, more chemically stable than original substance. Ex: water rusting a bike in the winter
What is Permeability + example
Property, material allowing fluids to absorb or pass through. Ex: raincoat
Example of Thermal and Electrical conductors
T: metals
E: copper
What is the importance of mechanical properties?
Helps determine how a material will react to different mechanical constraints, make better decisions on material choice when making stuff
What are the 2 types of wood? Why are they ideal?
Hard (deciduous trees) soft (coniferous); hard, elastic, resilient, tough; low thermal/electrical conductors; light
What is modified wood?
Thermally treated wood to increase ductility, often mixed with other substances
What are ceramics?
Heated inorganic raw materials usually containing oxides (ex clay, water). Bonds between compounds rearrange when heated.
Ex: brick, glass, tile, ducts
What are properties of ceramics?
- Low electrical/thermal conductivity
- Insulators
- Hard
- Heat/erosion resistant
What are metals and alloys?
M: shiny material extracted from ores, good thermal/electrical conductors, ductile/malleable (Fe, Al)
A: mix of metal with other substances, metallic or not, ferrous (iron) or non-ferrous, used to give greater strength/corrosion resistance
What are plastics?
Made from fossil fuels (petroleum, natural gas), good insulators, some as strong as metal, composed of polymers
Thermoplastic vs thermosetting plastics
Thermoplastic: can be heated and reshaped (recyclable)
Thermoset: remains permanently hard (non-recyclable_
Composite
Combined materials to obtain a material of stronger properties; matrix (skeleton) + reinforcement (strengthens)
Quench hardening vs tempering (metals/alloys)
QH: hardens but makes more brittle
T: tougher and less elastic
List ways to avoid the degradation of materials
Coating (varnish, paint, grease, resin VS metals)
Heating
Adding antioxidants
Adding uv-ray absorbants
