Introduction About Alloys of Copper Video:
A mixture containing two or more metallic elements or metallic and nonmetallic elements usually fused together or dissolving into each other when molten.watch Introduction About Alloys of Copper Video to learn more.
COPPER AND ITS ALLOYS
Melting point of copper – 10830 C Main properties of copper: High electrical and thermal conductivity Good corrosion resistance, Machinability, strength Ease of fabrication Non magnetic Has a pleasing colour Can be welded, brazed, and soldered Easily finished by plating and lacquering Electrical conductors- 99.9% Cu and identified as Electrolytic Tough Pitch (ETP) copper or Oxygen Free High Conductivity (OFHC) copper. Arsenical copper – ≈ 0.3% Arsenic – improved resistance to special corrosive conditions Free cutting copper – ≈ 0.6% Tellurium – excellent machining properties Silver bearing copper – 7 to 30 oz/ton silver – Silver raises the recrytallization of copper Prepared by: DrD.K.Hurreeram August 04 2
Cu and most of its alloys are homogeneous single phases, there are not susceptible to heat treatment and t heir strength may be altered only by cold working. Two general classes of temper for non heat treatable wrought copper alloys : cold worked and soft or annealed. The different cold worked tempers are obtained by cold working the annealed material a definite amount.
Brasses – essentially alloys of cu and Zn. Some of the alloys may contain small amounts of Pb, Sn, Al Variations in composition will result in desired colour, strength, ductility, machinability, corrosion resistance, or a combination of such properties Best combination of strength and ductility 70Cu- 30Zn Prepared by: DrD.K.Hurreeram August 04 3 Commercial Brass Brasses for cold worked (Alpha brasses) Brasses for hot working (Alpha Plus Beta Brasses) A. Alpha brasses – containing up to 36% Zn Relatively good corrosion resistance and good working properties. 1 Yellow α brasses – 20-36% Zn Good strength with high ductility Suitable for drastic cold working Common practice to stress relief anneal these bronzes after cold working to prevent stress corrosion cracking Subjected to selective leaching which can be minimized by small amount of tin or antimony 0.5-3% lead improves machinability Admiralty metal (71Cu-28Zn-1Sn)- improved strength and corrosion resistance Prepared by: DrD.K.Hurreeram August 04 4 Aluminium brass (76 Cu-22Zn-2Al)- better corrosion resistance form tenacious and self healing film 2 Red brasses – 5 to 20 % Zn Better corrosion resistance than yellow brasses and not susceptible to stress corrosion cracking and dezincification. Gliding metal (95Cu-5Zn), Commercial bronze (90Cu-10Zn), Red brass (85Cu-15Zn), Low brass (80 Cu-20 Zn) B. Alpha Plus Beta Brasses – 54 to 62 % Cu Consist of two phases – α + β1 β1 harder and more brittle than α at room temperature therefore more difficult to cold work. At elevated temperatures- single phase β becomes very plastic, hence excellent hot working properties. Prepared by: DrD.K.Hurreeram August 04 5 Muntz Metal – 60Cu-40Zn – has high tensile strength and excellent hot working properties Free cutting brass (61.5Cu-35.5Zn-3Pb) Forging brass (60Cu-38Zn-2Pb) Architectural Bronze – (57Cu-40Zn-3Pb) Naval Brass – (60Cu-39.25Zn-0.75Sn) Manganese bronze – (58.5Cu-39Zn-1.4Fe-1.5Sn-0.1Mn) Bronzes – up to 12 % alloying elements. Alloys of Cu and Sn, Al, Si, Be, in addition may contain P, Pb, Zn, or Ni A. Tin bronzes (Phosphor bronzes) B. Silicon bronzes C. Aluminum bronzes D. Beryllium bronzes Cupro-Nickels – Alloys of Copper and Nickel Nickel Silvers – alloys of Copper, Nickel and Zinc
Useful for CBSE, ICSE, NCERT & International Students
Grade : 8
Subject : Chemistry
Lesson : Metals and Non Metals
Topic: Alloys of Copper Video
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