Design and Launching Performance of Armature Coating with Low Melting Point Alloy

Abstract

Hydrodynamic lubrication is an effective method to improve the sliding electrical contact performance for electromagnetic railguns. A kind of U-shaped aluminum armatures coated with low melting point alloy was designed, and the solid coating could melt and form a fluid dynamic lubrication film during initial launching process. A series launching experiments were comparatively conducted about armatures with and without coating, the current waveform, the muzzle velocity, and the contact resistance were collected. The experiments results reached three aspects. First, the variation of the sliding electrical contact resistance of the armature/rail can be divided into three stages: rapid reduction stage, stabilization stage, and oscillation and rising stage. And the coating works mainly in the first stage. Second, with the increasing number of repeated launching, the amplitude of oscillations in the last stage gradually decreases, and the muzzle velocity tends to be stable. And in the last stage, with the increase of rail depositions, contact resistance gradually tends to stability. Third, compared with common armature, the armature coating with low melting point alloy occupies a shorter launching time interval and gets a higher muzzle speed. That work has some reference significance to the sliding electrical contact of the electromagnetic railgun.