Leaded copper is a

metal alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...

of copper with lead. A small amount of lead makes the copper easier to machine. Alloys with a larger amount of lead are used for bearings.

Brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...

and

bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloids such ...

alloys of copper may have lead added and are then also sometimes referred to as leaded copper alloys.Welter (2014) Leaded copper and its alloys have been used since ancient times.

Applications

Leaded copper alloys are used to make electrical connectors and mechanical bearings, especially in the automotive industry where high performance and reliability are required. Mechanical bearings can have high lead content. Such high lead content alloys are unsuitable for welding or brazing.

Machined alloys

Alloys with around 2-4% lead are used for machined copper applications, where the lead content lubricates the copper and makes it easier to machine. These include high-quality electrical connectors where a high current capacity and low electrical resistance are required. Such connectors are used in industrial automation and the automotive industry. Brasses (copper alloyed with zinc) may also be leaded for the same reason.Aalco, p.74.

Cast and sintered alloys

High-strength

casting Casting is a manufacturing process in which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a ''casting'', which is ejected ...

copper alloys typically contain less than 2% lead. Bearing alloys are often cast or

sintered Clinker nodules produced by sintering Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing ...

onto a steel backing. Softer alloys with a higher lead content are also used, for example in bushes where conformance to the opposite bearing surface is important.Engine Bearing Materials
catalogue, Glacier Vanderbell. Some casting alloys have over 20% lead content but, due to their toxicity, they are no longer used.

Toxicity

When lead alloys wear, lead is released into the environment. Lead is a heavy metal toxin and in recent times the use of leaded copper alloys has been reduced.

History

Signs of leaded copper use are found in the manufacture of ancient

Egyptian faience Egyptian faience is a sintered-quartz ceramic material from Ancient Egypt. The sintering process "covered he materialwith a true vitreous coating" as the quartz underwent vitrification, creating a bright lustre of various colours "usually in ...

. By 1500 BC leaded copper could be found across the Old World from East Asia to Africa and Europe. Enigmatic entries in a Chinese manuscript, the ''

Kao Gong Ji The ''Kao Gong ji'' (考工记), translated variously as the ''Record of Trades'', ''Records of Examination of Craftsman'', ''Book of Diverse Crafts'' or ''Artificers' Record'', is a classic work on science and technology in Ancient China, compiled ...

'' dating from around 300 BC, were deciphered by scholars in 2022, and seem to indicate that a pre-prepared copper-lead alloy named ''Xi'' may have been used in the preparation of ancient

s. Another copper-tin-lead alloy named ''Jin'' was also tentatively identified as a pre-prepared component of Chinese bronzes. This part of the manuscript relates to an attempt to standardise the quality of bronze manufacture.

References

Notes

Bibliography

Aalco brochure
Pages 70-85. *Jean-Marie Welter
Leaded Copper Alloys for Automotive Applications: A Scrutiny
European Copper Institute, 2014. Copper alloys Lead alloys {{alloy-stub