IMOS Module 4 - Copper/Bronze

UF IDS2935: Impacts of Material Science Quest Fall 2023

Properties of Copper and Bronze

• metals

• malleable

• opaque

• electrical conductor

• thermall conductor

• shiny, hard appearance

Copper v. Bronze

• pure element v. alloy of copper and impurity (arsenic or tin)

• melting point at 1084C v. 950C

• hardness of 80 MPa v. 700 MPa

• yield strength of 70 MPa v. 220 MPa

methods to strengthen bronze

• plastic deformation (permanent)

• elastic deformation (temporary) (dislocations → plastic deformation)

• work hardening (add dislocations)

• cold-rolling (increase tensile strength)

• impurtities (block disolations)

Copper reaction

• CuCO3 + heat = 2Cu + CO2

• 2CuCo2 + O2 = 2CO

• CuO + CO = Cu + CO2

Smelting process

• calls for mixing of ore with charchoal

• resource intensive

  • 140 lbs of wood = 20 lbs of charchol

  • 2 lbs of CuCo2 (malachite) = 1lb copper

• crucible and furnace

Phase diagram of Arsenic

• x-axis = composition (As)

• y-axis = temp.

• 6.8% at 685C is max solubility in copper

Arsenic alloy

• produces altered color

• increases the hardness of copper

• lower melting point

• oxidizes during smelting

• produces AsO3 bi-product (toxic)

Tin alloy

• increases strength

• heat treat ment changes strength

• adding too much tin can cause copper to be weaker

Tin v. Arsenic alloy

• dissolve more tin than arsenic (<15%)

• less toxic

• harder to find than arsenic

Copper Age

• 5500-3000 BC

• coppersmiths drew correlations between sources, conditions, and properties of copper

• deposits’ purity depends on the region

• used arsenic and tin as impurities

Bronze Age

• 3300-1200 BC

• process of smelting

• Otzi mummy is proof of copper smelting

• King Solomon’s temple

• parallel discoveries of copper around the world

• social impacts (health, mining, exploration, and experimentation)

• Trade developed around copper

  • England was the source of tin for Europe

  • Afghanistan also developed

• casting technology created productino of art, tools, and weapons

Trade of Bronze Age

• Egypt had gold

• Afghanistan had tin (tin was precious metal)

• Turkey had good metallurgists

• very entangled society

End of Bronze Age

• 200 yrs. of drought, mass starvation, and earthquakes

• ports shut down, centers are not used, and the tin supply chain stops

• sea people attack Egypt and Hittites

• society breaks down

• iron and Phencians rise

Annealing

cold treatment (less brittle, more efficient)

Copper ingots

circular shaped (England); ox-hide shaped (Mediterranean)

Copper ores

mMalachite (oxidized), Fahlerz (sulphides)

Pure Copper v. 10% Tin Copper Alloy

• melting point 1083C v. 1000C

• cast hardness: 50 HB v. 100 HB

• cold-worked hardness: 100 HB v. 230 HB

Metallurgy importance

1. technological: new skills became necessary and common

2. economic: raw and finished materials became abundant

3. social: introduces new scales of value and social divisions

Coppersmiths

• Germany

• Spain

• mythological smiths (Dwarfs)

Solar cells/Photovoltaic material

something that converts light into electricity; needs to beable to break bonds and create electrons and holes

Impacts of photovoltaics and solar cells

• 50% of CO2 comes from electricity generation

• 50-70% of the world relies of fossil fuels

• solar energy produces 50x less CO2 than fossil fuels

• solar energy is 300x cheaper than 40 years ago

• industry growth is making solar energy cheaper

• some regions need >9% of land area to produce enough energy

• hard to recycle Si at the end of life

Grid parity

new energy cost = grid cost

Semiconductor materials

• Si

• CdTe

• CIGS

• Pervoskites