Wear Behavior of Lubricant-Conditioned Copper Rails and Armatures in a Railgun

A solid lubricating interfacial compound (SLIC) has been used to condition the rails and armature of the NRL decoy launcher, a low-speed (100-140 m/s) railgun. The study tested the hypothesis that a very thin film would protect the sliding electrical contacts against damage by friction, wear, and arcing. The film, obtained by rubbing the rail and armature staples with a PTFE-based composite, dramatically improved launch reliability, increased projectile speed, and reduced armature damage and armature/rail arcing. High-speed (68 kfps) videos taken down the bore showed that the SLIC treatment could suppress light emissions from start of launch until the muzzle flash. The treatment also reduced or completely suppressed the spikes in the muzzle-voltage traces. Optical microscopy identified the damage mechanisms responsible for both rail and armature wear. The SLIC treatment reduced or eliminated arc damage in the breech, attachment of Cu shards to the rail, and both melting and abrasive wear of the staples. The effect of the rubbed film on wear behavior is discussed.