Copper and its alloys

Non-Ferrous Metalsand Their alloys

Copper and its alloys

Copper

• Copper (Cu) atomic weight 63.546 is a soft, malleable and ductile metal with very high thermal and electrical conductivity from the group of Coinage metals in the modern periodic table.

• There are 29 isotopes of copper. Cu and Cu are stable, with Cu comprising approximately 69% of naturally occurring copper. The other isotopes are radioactive.

• Copper is present in the Earth's crust at a concentration of about 50 parts

per million (ppm)

• Copper occurs as native copper or in mineral such as the copper sulfides

chalcopyrite and chalcocite, copper carbonates azurite and malachite and

the copper(I) oxide mineral cuprite.

Extraction Techniques• Copper ore is mined both underground and on the surface. Large excavations formed by

surface mining are called open-pit mines.

• Most of the copper ores mined today are oxide or sulfide ores.

• HYDROMETALLURGICAL operations are required for treating very poor grade oxide ores (LEACHING)

• PYROMETALLURGICAL treatments are given to the sulphide ores for their smelting and roasting.

• ELECTROMETALLURGICAL techniques are employed for the electro refining of blister copper or copper scrap.

Extraction of Cu from sulphide ores• Copper is extracted usually from the sulphide ore chalcopyrite (CuFeS2)

by smelting process.

• Ores containing 4% or more copper are treated by smelting process.

• There are following steps for the Pyrometallurgical extraction of copper from Chalcopyrite.

1. CONCENTRATION - By froath floatation Method

2. ROASTING

3. SMELTING

4. BESSEMERIZATION - Blister copper is obtained

Refining of Blister Copper• Blister copper is refined by electrolysis. The blister copper then undergoes "fire

refining.“• Air and natural gas are blown through the copper to remove any remaining sulfur

and oxygen. • The copper is cast into copper anodes and placed in an electrolytic cell. Once

charged, the pure copper collects on the cathode and is removed as 99% pure. • Blocks of blister copper are used as anodes and thin sheets of pure copper act as

cathodes. The cathode plates are coated with graphite in order to remove depositing copper.

• The electrolyte is copper sulphate (CuSO4) mixed with a little amount of H2SO4 to increase the electrical conductivity.

• Optimum potential difference is 1.3 volt for this electrolytic process.

Electrolytic Refining

Cu  → Cu+2+2e- Cu+2+2e- →  Cu Fe(s) → Fe2+(aq) + 2e–

Zn(s) → Zn2+(aq) + 2e–

Copper AlloysDeformable and heat treatable1) Al-Cu-Mg-alloys (duraluminium) 2) Al-Cu-Mg-Si-alloys (forgable) 3) Al-Mg-Si-alloys (corrosion resistance)4) Al-Zn-Mg-Cu-alloys (high strength)5) Al-Cu-Mg-Ni-Fe-alloys (heat resistance)

Rm → 500 N/mm2; Rp0,2 → 390 N/mm2; A → 25%

Deformable and non heat treatable1) Al-Mn-alloys 2) Al-Mg-alloys (magnalium)

Rm → 300 N/mm2; Rp0,2 → 150 N/mm2; A → 25%

Plane bearing alloys (for mono- and bimetallic bearing shells)Al-Sn; Al-Ni; Al-Cu-Sb Typical structure of bearing material

Copper alloy designations

Generic name UNS numbers CompositionWrought alloys

Coppers C10100-C15760 >99%Cu

High-copper alloys C16200-C19600 >96%Cu

Brasses C20500-C28580 Cu-Zn

Leaded brasses C31200-C38590 Cu-Zn-Pb

Tin brasses C40400-C49080 Cu-Zn-Sn-Pb

Phosphor bronzes C50100-C52400 Cu-Sn-P

Leaded phosphor bronzes C53200-C54800 Cu-Sn-Pb-P

Copper-phosphorus and copper-silver phosphorus alloys

C55180-C55284 Cu-P-Ag

Aluminum bronzes C60600-C64400 Cu-Al-Ni-Fe-Si-Sn

Silicon bronzes C64700-C66100 Cu-Si-Sn

Other copper-zinc alloys C66400-C69900  

Copper-nickels C70000-C79900 Cu-Ni-Fe

Nickel silvers C73200-C79900 Cu-Ni-Zn

wrought alloysdesignated C16000 - C79999

forged,rolled,hot and cold work can be done

Cast Alloys

Generic name UNS numbers CompositionWrought alloys

Coppers C10100-C15760 >99%Cu

High-copper alloys C16200-C19600 >96%Cu

Brasses C20500-C28580 Cu-Zn

Leaded brasses C31200-C38590 Cu-Zn-Pb

Tin brasses C40400-C49080 Cu-Zn-Sn-Pb

Phosphor bronzes C50100-C52400 Cu-Sn-P

Leaded phosphor bronzes C53200-C54800 Cu-Sn-Pb-P

Copper-phosphorus and copper-silver phosphorus alloys

C55180-C55284 Cu-P-Ag

Aluminum bronzes C60600-C64400 Cu-Al-Ni-Fe-Si-Sn

Silicon bronzes C64700-C66100 Cu-Si-Sn

Other copper-zinc alloys C66400-C69900  

Copper-nickels C70000-C79900 Cu-Ni-Fe

Nickel silvers C73200-C79900 Cu-Ni-Zn

Designated C81300 - C99999These alloys can be casted

Classification of copper alloysThere are five different classification of copper alloys

1)Unalloyed Copper

2)Brasses

Copper – Zinc alloysCopper – Lead alloys

Copper – Zinc alloys with Tin and Aluminium additions

3)Bronze

• Copper – Tin alloys• Copper – Aluminium alloys• Copper – Silicon alloys• Copper – Beryllium alloys

4) Cu-Ni based

• Cupronickel (Cu-Ni)• Nickel silver (Cu-Ni-

Zn

5) Nickel silver

1)Unalloyed Copper

• Copper content > 99.3%

Roughly classify into three categories• Electrolytic tough pitch: This copper contains 99.9% Cu with 0.045 O content

• Oxygen – free: Oxygen-free copper is produced from electrorefined cathode copper which is melt and cast in a reducing atmosphere of CO and N to prevent O.• Phosphorus deoxidized: Phosphorus is sufficiently added to produce phosphoruspentoxide P2O5

2)Brass

There are two Class of brass• The alpha alloys

with less than 37% Zinc. These alloys are ductile and can be cold worked.

• The alpha/beta or duplex alloys with 37-45% Zinc. These alloys have limited cold ductility and are typically harder and stronger

• Families of Brass– Cast alloy brasses

• Copper-Tin-Zinc alloys (red, semi-red and yellow brasses)

•  Cast Copper-Bismuth and Copper-Bismuth-Selenium alloys.

• Copper-Zinc-Silicon alloys (Silicon brasses and bronzes)

– wrought alloy brasses• Copper-Zinc alloys• Copper-Zinc-Tin alloys (Tin

brasses)• Copper-Zinc-Lead alloys

(Leaded brasses)

3)Bronze

• Cast bronze alloys

– Copper-Tin alloys (Tin Bronzes)

– Copper-Tin-Lead alloys (Leaded and high leaded Tin Bronzes)

– Copper-Tin-Nickel alloys (nickel-tin bronzes)

– Copper-Aluminium alloys (Aluminium Bronzes)

• Wrought alloys

– Copper-Tin-Phosphorus alloys (Phosphor Bronzes)

– Copper-Tin-Lead-Phosphorus alloys (Leaded Phosphor Bronzes)

– Copper-Aluminium alloys (Aluminium Bronzes)

Alloying additions in Copper

Brasses-General

Alpha Brasses (Alloys containing 36 % Zinc)

• Yellow Alpha Brasses

• Red Alpha Brasses

Alpha + Beta Brasses (54-62% copper)

• Defects in Brasses

• Intergranuler corrosion (Seasonal Cracking)

• Dezincification

Phase Diagram

Tin Bronzes

• Alloys of copper and tin

• Other Alloying Elements may also be present With The Exception of Zinc

• Also called Phosphor bronzes

• Phosphorus content (0.01-0.5%)

• Tin Content (1-11%)

• High corrosion resistance , Toughness ,Low coefficient of friction, free from seasonal cracking

Phase Diagram

Silicon Bronzes

• Alloys of Copper And Silicon• Maximum Solubility In Alpha

Phase is 5.3 and decrease with the temperature

• Alloys contains less than 5% Si are single Phased

• These are the Strongest of the work hard enable Copper Alloys

• Their Mechanical Properties are comparable to mild steel and corrosion resistance is comparable to copper

• These are used for Tanks , pressure vessels , Marine construction , hydrulic preassure lines

Phase Diagram

Aluminium Bronzes

• Alloys of Al & Cu• Maximum solubility of Al in α-solid

solution is 9.5%• Commercial Al bronzes contain (4-

11%)Al• Alloys containing up to 7.5% al are

single phase, other are double phase• Other elements are also added

intentionally e-g , Fe , Mn , Si , Ni• Iron Increases strength , silicon

improves machinability , Mn improves sound casting

• Single phase Bronze show good cold working propertis along with high corrosion resistance to water and atomsphere

• These are used for water condenser tubes,nuts , bolts, corrosion resistance vessels ,and in marine application

Phase Diagram

Beryllium Bronzes• Alloys of Cu & Beryllium

• Maximum solubility in Alpha solid Solution is 2.1 % and decreases to 0.25 % to room temperature

• It is increased by age hardening

• They have excellent formability ,high tensile strength , creep resistance , high electrical conductivity

• These are used in diaphrames , surgical instrument ,bolts & screws , firing pins , dies.

Phase Diagram

Cupro-Nickels• Alloys of Cu & Ni , contains upto

30 % Ni

• Cupronickels Alloys are single phase alloys

• No heat treatment is required

• Properties are improved only by cold working

• They have high fatigue resistance , high corrosion & erosion resistance toward sea water

• These are widely used in condenser , heat exchanger tubes , coastal power plants

Phase Diagram

Nickel Silver

• Alloys of Cu-Ni-Zn

• Commercial Alloys are contain Cu (50-70%) , Ni (5-10%) , Zn (5-40%)

• If copper is more than 60 % these are single phased ,ductile & easily workable at room temp.

• Addition of Zinc imparts silver-blue-white colour ,good corrosion resistance.

• These are Excellent base metals for plating with Cr ,Ni ,Ag

• These are used For Rivets, screws, Costume jewelry , name plates & radio dials

Electrical Applications

• Approximately 65% of copper produced is used for electrical applications.

• Power generation and transmission generators, transformers, motors, busbars and cables provide and deliverelectricity safely and efficiently to homes and businesses.

• Electrical equipment - providing circuitry, wiring and contacts for PCs, TVs and mobile phones.

Copper is used in the manufacturing of heatsinks. In a microchip, copper is commonly used for what is known as the 'global

interconnects' because of its good conductivity. These are the wires that connect different sections of the chip together.

Cu-Ni 70-30 alloy is used in steam generators, heat exchangers, coolers, condensers, tanks, pipework, valves and fittings in electricity generation by Nuclear means

Automotive Applications• Almost all automation components• Automotives radiator is made of copper-brass alloy.

Other Applications

Inner grooved Heat radiation technology

Hardware: Gears and pinions Industrial: Automatic high speed screw machine parts