Plated armature contacts for solid armature electromagnetic railgun launchers

Solid armature firing tests have shown that, under electromagnetic railgun firing conditions, the armature contact areas wear excessively and after transitioning, lose contact with the rail surfaces. It is desirable to maintain rail contact as long as possible. Previous work, regarding the engineering design of metal armature contacts has shown that copper, plated on aluminum armatures, as a contact material in rail guns, may be over twice as good as aluminum. It was stated, also, that the armature contacts obey the same physics as pin-on-disk contact experiments have shown. Recent work has led to the development of a process for the copper plating of aluminum 7075-T6 armature contact surfaces. This paper reports on the armature fabrication process, the copper plating, an the associated testing required to assure that the copper adheres to the aluminum armature substrate material. The armatures were test fired at ARL and the results of these tests and observations are presented.<>