Material Transfer of Composite Contact Materials

Composite technology provides very promising possibilities of improving one property of a given material without changing the other for the worse. The material transfer behavior of some fiber composite materials like AgNi and CuPd has been studied. Fiber composite contact materials can be fabricated in a simple and thus inexpensive way by bundling and simultaneous deformation of clad wires. It was found that there is no distinct difference in material transfer behavior between AgNi composite materials with a given composition but with different structures. On the other hand there is a great difference between CuPd composite materials and CuPd alloys of the same composition. Whereas contact rivets made out of CuPd fiber composites show only a slightly roughened contact surface after switching direct current, the corresponding alloys show peaks on the cathode and craters in the anode. This is due to the better thermal conductivity of the fiber composites. It can be shown that, by means of composite technology, material-transfer resistent contact materials can be fabricated with a much lower noble metal content than the normally used alloys.