A comparison of the wear behaviors of six elemental wire conductors

The goal of this work is to relate properties of armature materials to observed armature performance. In simple railgun electromagnetic launchers, the wear behavior of the widely-used aluminum alloys as sliding electrical contacts on copper rail conductors leads to a progressive change on the rail conductor surface as debris from the armature/rail interaction adheres to the rail. Here, the authors compare the behavior of wires of silver, copper, aluminum, nickel, molybdenum, and tantalum as armature conductors on ETP copper rail conductors. Some of these wires were also tested on molybdenum rail conductors to assess the effects of rail hardness. The emphasis is on the effect of current/contact under current densities greater than 1 kA/mm/sup 2/ on the wear behavior and eventual failure of the armature wire conductors. Characteristics of material transfer and a descriptive model are presented. The value of temperature-dependent properties such as hardness and surface tension are related to materials transfer of the wire conductors as the contact surface deforms and flows in response to specific driving current profiles.<>