Materials and Manufacture Flashcards
Describe the thermal and electrical conductivity of metals and alloys
Good thermal and electrical conductors
Describe the range of densities in metals and alloys, and compare this to non-metals
Metals and alloys have a wide range of densities but all are generally higher than non-metals
What is an alloy, and why are they used more commonly than pure metals?
A type of metal made by combining 2 or more different types of metallic elements
Used more commonly since they’re harder than pure metals, due to having different sized atoms in the structure so layers can’t slide over each as easily
What is heat treatment of metals and what is the purpose of it?
It’s where you heat a metal to the point where it isn’t molten or melting, then cooling it down in a controlled way to select various desirable mechanical properties
What are 2 types of polymer?
Natural
Synthetic
What is an elastomer?
A polymer with both viscosity and elasticity and with weak intermolecular forces
Are polymers good thermal conductors or insulators?
Good insulators
Why do polymers have a good strength-to-weight ratio when they have low strength?
Because they have a low density
How resistant are polymers to corrosive chemicals?
Very resistant
What is a thermoplastic polymer?
A plastic polymer that becomes moldable at a certain temperature and solidifies upon cooling
What is a thermosetting polymer?
A plastic polymer that becomes irreversibly hard on heating or by addition of special chemicals
Why are thermosetting polymers stronger but much more brittle?
The molecular chains are tightly cross-linked, meaning they will not soften at a high temperature
What are ceramics?
A group of crystalline or amorphous materials
What is the difference between crystalline and amorphous?
Crystalline solids are arranged in a regular pattern, whereas the amorphous solids do not show a regular arrangement
What can be said about the strength and hardness of ceramics when under compression?
High hardness and good strength
