Overview of Copper

Copper ranks highest in commercial importance of all conductor materials. With the exception of silver, it has the highest conductivity, volume for volume, of any other metal or substance.  In addition to its high conductivity, it has sufficient strength to be used for a limited number of structural purposes. It is easily rolled and drawn at a comparatively small expenditure of power. Its has a high resistance to deterioration by oxidation which is due to the fact that an initially thin surface coating of oxide protects the metal underneath from further oxidation. Copper can be brazed, soldered and tinned with relative ease. However, it cannot be easily welded because its high thermal conductivity will not permit a sufficient temperature build up in a concentrated area. Pure copper is not used extensively for casting owing to its high cost and the difficulty in casting it.

Conductivity standards of copper apply to pure copper in the annealed or unrestrained condition, for as the metal is cold worked its resistance is increased and conductivity decreased. The cold working of copper greatly increases its ultimate tensile strength as shown by the marked difference between cast copper at approximately 24,000 lbs. per square inch and hard-drawn copper wire which attains ultimate tensile strengths as high as 70,000 lbs. per square inch. The introduction of impurities in small amounts, likewise exhibits a marked effect on the conductivity of copper, for example, the introduction of approximately .005% of phosphorus will depress the conductivity of copper from 100% to 94%.

PHYSICAL PROPERTIES OF COPPER