The Bronzes
The coinage bronze employed for making coins in earlier days contains 95% copper, 4% Sn and 1 % Zn. The Zn acts as a deoxidizer. Such alloy is soft and ductile.
Admiralty gun metal comprises 88% Cu, 10% Sn and 2% Zinc. This bronze is usually cast to generate steam and water fittings and bearings. The addition of Pb enhances the alloy's pressure tightness.
Phosphor bronzes are usually utilized in manufacture of bearings, bronze springs and hard drawn wires. In addition to tin they have minute percentage of phosphorous like alloying element. 0.2% P forms Cu3P that is a hard compound. This acts as deoxidizer and enhances fluidity.
Copper aluminium alloys posse high strength along with good resistance to fatigue, abrasion and corrosion and are golden in colour. Aluminium can dissolve in copper to the level of 9% and greater content than these encourage brittleness. Wrought alloys that are good for hot and cold working applications contain 5 to 7 percent Al. Casting alloys contain 10 percent Al. Minute percentage of Fe, Nickel and Mn are added to casting alloys to create them more simply heat treatable. Aluminium bronze is well identified for its colour and often termed as Imitation gold. Al bronze compares well along with the strength of steel.
Bronzes in common are identified for the following characteristics as:
- costlier than brass,
- better corrosion resistance,
- stronger than brass, and
- Bearing material.