Phosphor Bronze-An overview

Phosphor bronze is an alloy of Copper, Tin ( 3.5 to 10%) and Phosphorous (1%).  Phosphor bronze is used in applications which require resistance to fatigue, corrosion and wear.  They are used in springs, bolts, etc. 

In Electrical Engineering, phosphor bronze is used in springs in instruments such as galvanometers and other instruments.   The current is guided to the coil through the phosphor bronze rings.  Phosphor Bronze has low resistivity. 

The phosphor bronze is used as a wound spring which is used to provide the restraining torque in the instrument. 

Another important characteristic of phosphor bronze is that it is non magnetic. So it does not interfere with the instrument's functioning.

Phosphor bronze is also used for contact springs in Electric motors.  When plated with silver, the conductivity of phosphorous increases further.