Influence of electric current on the static friction of metal surfaces in air

The static coefficients of friction of aluminium, copper, brass and tin interfaces and aluminium mated with copper, brass and tin have been measured at light mechanical loading with the simultaneous passage of 50 Hz alternating current through the interface. When one surface was aluminium the friction was seen to decrease with increasing current. With brass/brass and copper/copper surfaces there was little dependence on current, while for tin/tin surfaces there was an increase in friction. These results indicate that the performance of aluminium power connectors which rely on frictional forces to maintain mechanical integrity may be in doubt during fault current conditions.