Summarize and analysis of rail-gun's grooving phenomenon with large pulse current and high-velocity sliding electrical contact

Because the electromagnetic railgun's main current can reach several MA and the muzzle velocity is more than 2 km/s, launching in this harsh environment in barrel will cause grooving to the rail. Using existing experimental data and references, we described the position, depth, length, and shape of the grooving, and introduced the shape, thickness, layers and composition analysis of the deposition. On the basis of the experimental phenomena of grooving and deposition, we also analyzed their formation mechanism. Two causes of the grooving in initial period are hypothesized, the one is material yielding due to high contact pressure, and the other is material softening at elevated temperature. And then as the temperature rises, the armature is melting. There are two explanations of the formation mechanism of the continuously extending grooving. One is that it will be caused by mechanical impact of high-pressure molten aluminum, which is likely to contain un-melted granules of aluminum alloy. The other is that the aluminum and copper will form a eutectic liquid, when the liquid is scrubbed from the surface by the flow, the copper surface will recede. Finally, on the basis of the formation mechanism of grooving and deposition, we suggest to improve the design of the launcher and armature, and to improve the lifetime of the rail. The formation mechanism of grooving summarized will be benefit to the high-speed sliding electrical contact theory with high currents.