Bronze is an alloy of copper and tin. – The first metal purposely alloyed by the smith – May contain up to 25% tin Brass is an alloy of copper and zinc. – Contain 5-30% zinc – The zinc increases the strength of the copper. – Ductility and formability are also increased. Bronze Mask Bronze and Brass
Copper, Brass, and Bronze Copper is one of the oldest metals- used by early civilizations Copper is FCC Copper ores are found close to the earth’s surface as –oxide (cuprite) –sulfide (chalcopyrites, bornite, chalconite, and covellite) –carbonate (malachite and azurite) –silicate form (chrysocolla) Copper properties –high thermal is 10 times that of steel, useful for chill, casting molds –melting point is 1981 F (however, oxides form when Cu is exposed to heat or environmental conditions thus surface treatments are needed. –electrical conductivity requires relatively pure copper –Silver, cadmium, and gold can be added to increase strength without significantly reducing conductivity
Copper Applications Copper and Copper alloys are used for tubing and pipe and in heat transfer applications. Copper compounds are toxic and thus not used in food-related Copper Alloys –brass: alloy of copper and zinc –bronze: alloy copper and elements other than zinc Copper is very useful in electrical applications –A large percentage of Copper produced is used in electrical and electronic industries. –At very low temps (absolute zero), Cu becomes a superconductor. –Superconductors have very low resistance to current flow. –A current started in a superconductor will flow almost indefinitely. –Magnetic Resonance Imaging (MRI) devices used in hospitals for diagnosing patients are examples of superconductivity. –Future uses may include magnetic levitation (Mag-lev) trains being prototyped in Japan today.
Unalloyed copper: – So soft and ductile that it is difficult to machine – Unlimited capacity to be cold worked – Highly resistant to corrosion in diverse environments Copper alloys: strengthened by cold working and/or solid-solution alloying. Bronze and brass are two common copper alloys. Applications: costume jewelry, cartridge casings, automotive radiators, musical instruments, electronic packaging, and coins Copper and Its Alloys
Copper Smelting Process –Copper ores are cleaned in a floatation process to remove silica (sand), aluminum oxide (clays), and other unwanted materials. –Floatation process grind ores into powder and place in water. foaming agent (soap) is added, creates a froth, brings the copper ore to surface. Ore is skimmed off leaving undesirable materials in the water. –Concentrated ore is roasted in an oven to convert iron sulfides to iron oxides and contains copper oxides, copper sulfides, iron sulfates, silicates, and other impurities. –Ores are placed in smelting furnace and melted at 2600 F. –Melted ore is called matte copper, containing 30% copper. –Mixture placed in a converter with a flux (silica), air is blown through Sulfur is oxidized and removed from the melt by Sulfur dioxide bubbling through the ore leaving blister copper. Copper is 98% to 99% pure. –Slag drawn off t he mixture is further refined to extract other Au, Ag.
Copper Electrical Wire Production Copper Electroplating –Small amounts of impurities reduces conductivity of the copper. –Impurities removed by electroplating Blister copper is remelted and cast into plates called anodes (+). Refined copper cathodes (-) are placed on the other side in staggered pairs (figure below) Plates are immersed in plating solution of copper sulfate. Anode connected to Positive and cathode to Negative terminal of direct current. When current is applied, the metal in the anode goes into solution and the copper is plated on the cathode. Impurities in anode metal are left in the solution Plating on cathode will be 99.9% pure copper. –Copper used in electrical wire is remelted using an oxidizing flame to prevent sulfur from being reabsorbed into the copper and keep oxygen less than 0.04%, called electrolytic tough pitch (ETP) copper. –Phosphorous is added to control the amount of oxygen in copper, oxygen-free high conductivity (OFHC) or phosphorous deoxidized (DHP) copper
Copper Alloys Copper alloys are among the oldest of metallic alloys –Alloying elements increase strength,hardness, machinability, appearance, and cost –Melting points of copper alloys are lower than that of pure copper. –Alloying elements Aluminum, beryllium, lead, manganese, Nickel, phosphorous, silicon, tin, and zinc –Brass: copper-zinc alloy Zinc is added to increase strength, improve ductility, and improve machinability –Bronze: copper-tin alloy Tin is added to improve strength, hardness, and ductility; reduce cost –Names, compositions, and typical uses of copper alloys There are more alloying elements in brasses than copper and zinc alone. Brass and bronze are multi-component systems and have a phase diagram
Copper-Zn Phase Diagrams Phase Diagram for Copper Zinc There are more alloying elements in brasses than copper and zinc alone. Brass and bronze are multi-component systems and have a phase diagram. Alfa brasses: up to 36% Zn can dissolve in Copper and form one phase. FCC Beta phase is BCC Alfa + Beta is 38% to 46% Zn Brass Varieties: Yellow & Red –Red » less alloy better corrosion »most ductile and malleable
Copper-Tin Phase Diagrams Bronze refers to metal alloys containing copper with any other metal –Traditionally copper and tin –Phosphorous added to improve ductility: phosphor bronzes (1% to 11% P) –Red Bronzes contain more than 90% copper –Al bronzes are heat treatable and highest strength bronzes. Uses structural –Si bronzes are high strength alloys of Cu and Ni. Uses in tubing as per resistance to attack from fresh and salt water –Be bronzes (<2% Be) are heat treatable and highest strength copper alloy. Non-sparking when struck by another metal. Uses with explosives. –Nickel bronzes named Nickel silver and German Silver used for coins »Present dimes and quarters are 75% Cu and 25% Ni clad over and inner core of copper
2.2. Cu and its Alloys http://www.copper.org/ General properties Yield strength: 20-200 MPa Tensile: 200-400 MPa Young’s modulus: 117 GPa FCC structure: excellent formability Exhibits no sub-zero T embrittlement Castable and weldable Corrosion resistant High thermal conductivity High electrical conductivity 50% copper produced are consumed as electrical conductors Copper Brass (Cu-Zn) Berrylium copper (Cu-Be) Bronze (Cu-Sn, Al,Si) Cupronickel (Cu-Ni) Nickel silver (Cu-Ni-Zn)
Blister copper - An impure form of copper obtained during the copper refining process. Applications for copper-based alloys include electrical components (such as wire), pumps, valves, and plumbing parts, where these properties are used to advantage. Brass - A group of copper-based alloys, normally containing zinc as the major alloying element. Bronze - Generally, copper alloys containing tin, can contain other elements. Copper Alloys
Cu Alloys Designation (Copper Development Association: CDA) CDAUNS 100C10000 …... 799C79900 800C80000 …… 999C99900 Wrought Cast
Cu and its Alloys Commercially Pure Coppers Electrical tough pitch (ETP) copper: used for conductors Deoxidised phosphorus copper: heat conductors, piping, tubing, heat exchangers Beryllium Copper (1.5-2.0%Be) (C172000) precipitation hardened high strength comparable to steels: up to 1400 MPa used for springs, bearings, high-strength components Bronzes (up to 13%Sn) Silicon bronze (Cu-Sn-Si, <4%) Aluminium bronze (Cu-Al, 8-12%) excellent castbility good metal-metal wear resistance when lubricated
Cu and its Alloys Brasses (up to 50%Zn) -brass: FCC, up to 35%Zn red-brass: 15%Zn yellow-brass: 30%Zn, (strength increases with increasing Zn%) Naval brass, admiralty brass: yellow brasses + 2% Sn to improve pitting resistance in seawater. -brass:BCC+FCC, 40-50%Zn: Muntz metal (UNSC28000) Copper-Nickel Alloys (Cupronickel, 90/10 and 70/30) High ductility and formability excellent corrosion resistance in seawater Strengthened by cold working 85/15 alloy for coinage 70/30 alloy for seawater piping, heat exchangers Copper-Zinc-Nickel Alloys (Nickel Silver) Pale yellow at 10-12%Ni, silver white at 20-30%Ni Decorative applications and silver plated dinnerware
Cu and its Alloys There are some 800 Cu alloys commercially available. The average designer could solve most application problems with ~10 alloys: ETP copper: C11000 (99.9%) (electric tough pitch copper) DHP copper: C12200 (99.9%) (deoxidized high phosphorus copper) Beryllium copper: C17200 Red brass: C23000 (85Cu-15Zn) Yellow brass: C26000 (70Cu-30Zn) Free cutting, yellow brass: C36000 (62Cu-35Zn-3Pb) Tin bronze: C90700 (89Cu-11Sn) Lead tine bronze: C94300 (70Cu-5Sn-25Pb)
Brass — An Alloy of Copper and Zinc Fig. 9.17 The copper-zinc phase diagram.
Generic name Major componentsUNS designation number Coppers>= 99.3% CuC10100…C15999 High-copper alloys > 96% Cu but <99.3% Cu C16000…C19999 BrassesYellow BrassesCu-ZnC21000…C28999 Leaded BrassesCu-Zn-PbC30000…C39999 Tin BrassesCu-Zn-Sn-PbC40000…C49999 BronzesPhosphor BronzesCu-Sn-PC50000…C52999 Lead Phosphor BronzesCu-Sn-Pb-PC53000…C54999 Copper-Phosphorous alloysCu-P, Cu-P-AgC55000…C55299 Copper-Silver-Zinc AlloysCu-Ag-ZnC55300…C60799 Aluminum BronzesCu-Al-Ni-Fe-Si-SnC60800…C64699 Silicon Bronzes\Silicon BrassesCu-Si-SnC64700…C66199 Other copper-zinc alloysCu-Zn-…C66200…C69999 Copper-Nickels\(Copper-Nickel-Iron Alloys) Spinodal Bronzes Cu-Ni-Fe Cu-Ni-Sn C70000…C73499 Nickel SilversCu-Ni-ZnC73500…C79999 Wrought copper alloys designation
Temper designation F: As Fabricated O: Annealed H: Strain-hardened W: Solution heat-treated T: Thermally treated to stable tempers
Nickel and cobalt alloys are used for corrosion protection and for high-temperature resistance, taking advantage of their high melting points and high strengths. Superalloys - A group of nickel, iron-nickel, and cobalt- based alloys that have exceptional heat resistance, creep resistance, and corrosion resistance. Nickel and Cobalt Alloys
Figure 13.8 (a) Microstructure of a superalloy, with carbides at the grain boundaries and γ΄ precipitates in the matrix ( 15,000). (b) Microstructure of a superalloy aged at two temperatures, producing both large and small cubical γ΄ precipitates ( 10,000). (ASM Handbook, Vol. 9, Metallography and Microstructure (1985), ASM International, Materials Park, OH 44073.)
2.3. Ni and its Alloys http://www.incoalloys.com/ http://www.haynesintl.com/ http://www.nidi.com/ Pure Ni has a FCC structure, similar melting temperature (1450°C), elastic modulus and density (7.85) to steels, but twice electrical conductivity. It is highly corrosion resistant in many environments. Some 2/3 of it production are consumed in stainless steels. Most Ni alloys are proprietary: they are often identified by trade names. Pure Ni Nickel 200 (UNSN02200), very corrosion resistant in strong caustics, used as coating or cladding in pipes, pumps, valves, autoclaves, etc. Ni-Cu Ni Ni-CrNi-Cr-FeNi-Mo Ni-Cr-Mo
Ni-Cu Alloys MostNi-Cu alloys come from the Monel series, manufactured by Inco Alloys (Special Metals). These alloys are excellent in resisting corrosion in seawater and are also used to handle H 2 SO 4, HCl and deaerated HF. Typical application include marine engineering, chemical and petrochemical processing equipment, valves, pumps, shafts, fittings, heat exchangers, etc. Example: Monel 400 (UNS N04400): 66Ni-30Cu-1Fe-3%Al Ni-Cr, Ni-Cr-Fe Alloys MostNi-Cr alloys come from the Inconel and Incoloy series manufactured by Inco Alloys. These alloys are particularly good for resisting oxidation at high temperatures and corrosion in Chloride-containing environments, while having high strengths. Typical applications include marine engineering, chemical processing, gas turbine engines, rocket engines, nuclear reactors, pressure vessels, heat treatment equipment, heat exchangers, heating element sheathing, etc Examples: Inconel 600 (UNS N06600): 72Ni-15.5Cr-8Fe Inconel X725 (UNS N07750): 73Ni-15.5Cr-7Fe-2.5Ti Incoloy 800 (UNS N08800): 32.5Ni-46Fe-21Cr
Ni-Mo, Ni-Cr-Mo Alloys These alloys are manufactured by Haynes International as Hastelloy series. They are used in severe corrosion environments, such as HF, high temperature and high stress- corrosion cracking risk conditions. Example: Hastelloy B-2 (UNS N10665): 65Ni-28Mo-2Fe Stainless steels Other metallurgical products: Ni alloys Superalloys Plating Miscellaneous 65% 20% 9% 6%