Classification Flashcards
What are the different classifications of materials?
Metals
Ceramics
Polymers
Composite
What are the main classes of materials used in chemical engineering?
Metals and polymers (plastics)
Why are composites not commonly used in engineering?
£xpensive
List six considerations when choosing a material suitable for pipes, tanks and reactors.
Wear (flowing environments)
Corrosion (reactive environment)
Large temperature and pressure ranges
Extreme environments
Long service life
Safety
What are the different types of metals?
Base
Alloy
Precious
Noble
Ferrous
What is a base metal?
Common, cheap metal which oxides and corrodes easily (eg. brass, aluminium, steel, copper).
What is a precious metal?
Rare naturally occurring metals.
What is an alloy?
Mixture of two or more elements
What is a ferrous metal?
Metal containing iron
What is a noble metal?
Metals resistant to corrosion or oxidation (eg. platinum, palladium, rhodium) .
Name three common alloys?
Steel
Stainless steel
Brass
Give two properties of steel.
High yield strength
High tensile strength
Give two properties of stainless steel.
Rust and corrosion resistant
High tensile strength
Give two properties of brass.
Malleable
Corrosion resistant
How do you produce materials from ore?
Mined
Crushed and screened
Blast furnace (reduces carbon to increase stiffness)
Electric furnace (adds elements)
Argon Oxygen Decarb
List six characteristics of metals.
High stiffness (YM).
Ductile (can be deformed).
Stronger by alloying, mechanical and heat treatment.
Good electrical and thermal conductors.
Reactive and corrode rapidly.
Pure metals are soft and easily deformed.
List six benefits for metal pipes.
High strength (good for heavy or pressurised materials)
Non porous (can contain fluids)
Easy to process into shape
Available worldwide
High thermal conductivity
Recyclable
List three drawbacks for metal pipes.
Prone to corrosion (particles wear away metal).
High thermal conductivity (Not good for transporting hot fluids as heat will be lost in piping).
Cheaper alternatives.
Name four types of plastic.
Thermoplastics
Thermosets
Elastomers
Copolymer
Draw a diagram of a thermoplastic and state what it is.
A plastic which becomes mouldable above a specific temperature and returns to a solid state upon cooling.
Chemical structure does not change.
Draw a diagram of a thermoset and state what it is.
Strong plastic that cannot be remelted, suitable for high temperature applications.
What is the key difference between a thermoplastic and thermoset?
Thermoplastics can be reheated and shaped whereas thermosets undergo irreversible structure changes after heating.
What is an elastomer?
Plastic with low YM and high failure strain.
Withstands large mechanical stress and deformation. Returns to original state. (e.g rubber band).
What is a co-polymer?
Plastic made of different monomers to change material properties (e.g. tyres).
