Copper and Bronze Flashcards
Properties of copper and bronze
Metallic, Malleable, Opaque, Electrically Conductive, Thermally Conductive, Orange, Shiny, Hard
Copper vs Bronze
Copper - a pure element - Melts around 1084 C Bronze -is an alloy of copper and impurity(Usually tin or arsenic) -Melts around 950 C
Why is smelting copper good?
It provides increased temperatures as well as the pathway to a chemical reaction that removes metals from their ores.
What is basic formula for making copper?
Take malachite (CuCO3) and charcoal (Carbon), heat them up together, and copper will form.
What were some early problems of making copper?
- Resource Intensive - Required 140 pounds of wood to make 1 pound of copper
- Must find lots of copper ore
Basic Chemical Equation for smelting copper
Cu2O + CO => 2Cu + CO2
Essentially some copper composite combusted with carbon to produce copper and carbon dioxide
Copper vs Bronze Strength
Copper (Hardness: 80 MPA, Yield Strength: 70 MPa)
Bronze (Hard: 170 Mpa, Yield Strength: 220 MPa)
-It is harder because it is a composite
Strengthening Copper
Work Hardening, Solid Solution Hardening, beating on the material with a hammer
What is Work Hardening?
Work hardening is the process of adding a lot of dislocations making metal stronger as they are unable to move. This is done for copper by cold rolling it.
What are dislocations?
They are line defects that exist in metals. As the number of dislocations in a metal increase, they get tangled and unable to move making the overall metal stronger.
What is Solid Solution Hardening?
A type of alloying where impurities are added to the copper. In most cases it is tin or arsenic. Early on they used arsenic but later used tin. By adding these other atoms, dislocations can be blocked thus slowing them down.
What are Phase Diagrams?
It tells how property changes as a function of how much of an impurity there is
What does adding Tin do to copper? Why is adding too much tin bad?
It increases tensile strength. It can make it brittle
Why was bronze so revolutionary in history?
The development of bronze enabled casting technologies to be developed for later production of vessels, weapons, tools, and art.
Why did bronze age end?
This is because bronze created a highly developed and dependent network. Egypt had gold, Afghanistan had the tin, Turkey had the good metallurgists, etc. Towards the end, there was 200 years of drought, starvation, eqarthquakes, etc. Society began to crumble, trade diminished, and what drove the nail in the coffin was a mysterious ‘sea people’ who destroyed Egypt and Turkey essentially destroying the system that the production and trade of bronze relied on.
