Materials - Metals Flashcards
What categories can metals be divided into?
Non ferrous
Ferrous
Alloy
What makes aluminium quite corrosion resistant?
It oxidises quickly, the coating of aluminium oxide is clear, colourless, and non-staining. Stops air, water and chemicals reaching the metal.
What is anodization?
an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish.
What can aluminium conduct?
It conducts heat and electricity very well.
Aluminium is both d_______ and m__________.
Ductile and malleable.
When aluminium is polished it is ___________ ______________.
Highly reflective.
Aluminium has the highest ________________________ of any metal.
Strength-to-weight ratio.
What happens to the strength of Aluminium as temperature rises?
It reduces.
What is an environmental benefit of aluminium?
It can be very easily recycled and is 100% recyclable.
What are the reasons Aluminium is commonly used in foil?
It is impermeable and odourless.
What are some disadvantages of aluminium?
It is difficult to weld which limits the ways it can be joined together.
Not very hard.
Advantages of copper
Good conductor of both heat and electricity
Very malleable and ductile
Corrosion resistance
Tough
Disadvantages of copper
Poor tensile strength
Not very hard - scratches
Advantages of silver.
Very malleable
Ductile
Good conductor of both electricity and heat
Anti bacterial
Attractive
Disadvantages of silver
Soft and scratches easily
Not very corrosion resistant, tarnishes quickly
What is pewter 90% made up of?
Tin
Advantages of pewter
Malleable
Non-elastic
Easily fusible with other metals
Non-corrosive so water-tight
Why is pewter excellent for coating other metals such as in production of cans for preserving food?
Does not impart flavour to the food and doesn’t leech chemical into food content
Disadvantages of pewter
Soft and not hardwearing
Dents easily
Low mp
Low strength
Expensive to mine and extract
Advantages of stainless steel
High corrosion resistance
Heat and fire resistant
Easy to clean - non reactive to cleaning chemicals
Good strength to weight ratio
High tensile strength
Disadvantages of stainless steel
Scratches and dents
Difficult to weld
High initial cost
Advantages of brass
High corrosion resistance
Ductile and malleable
Easily worked
Attractive
Good flow characteristics - casts well and takes detail
Reasonable conductor
Antimicrobial properties
Disadvantages of brass
Still fairly expensive
Scratches
What are the different types of steel heat treatments?
Tempering
Annealing
Work Hardening
Normalising
What is tempering?
The heat process used to increase the toughness of iron-based alloys.
Advantages of tempering
Helps to relieve stress making the metal easier to weld or machine.
Increases strength while making the material more flexible and ductile.
Increases hardness and introduces wear-resistant properties to the surface or through entire metal.
Disadvantages of tempering
Time consuming
Inconsistent hardness
Discolouration
Limited control over mechanical properties
What is annealing?
The heat treatment process that changes the physical and sometimes chemical properties of a material to increase ductility and reduce hardness to make it more workable.
Advantages of annealing
Increase workability
Increases ductility
Increases toughness
Reduces hardness
Disadvantages of annealing
Can cause defects
Needs temperature control while cooling down
Time consuming
Can alter the properties of the material
What is work hardening?
The process by which a materials load-bearing capacity increases during plastic deformation.
Advantages of work hardening
High impact strength
Increases toughness
Disadvantages of work hardening
Lower ductility
More brittle
Where is tempering used?
In tools, springs and structured steel
Where is annealing used?
In machining tools
Where is work hardening used?
Mining chutes, conveyors, grizzlies, screens, bucket lips
Advantages of duralumin
Strong
Hard
Lightweight
Malleable
Machines well
What is duralumin made up of?
95% aluminium
4% copper
0.5% manganese
0.5% magnesium
Disadvantages of duralumin
Not very corrosion resistant
Soft - can bend easily
Where is duralumin used?
Aircraft, speedboat and automobile frames, pressure cookers
Advantages of bronze
High thermal and electrical conductivity
Corrosion resistance
Hard
Tensile strength
Resistant to metal fatigue
Disadvantages of bronze
Susceptible to “bronze disease”
Hard to work with
