Experimental study of armature melt wear in solid armature railgun

Transition is an important issue in rail electromagnetic launches which limits the performance of electromagnetic launch systems. In the launch progress, wear on contact surface of armature significantly affects the morphology of contact surface and armature structure. Studying wear, contact resistance and sliding friction coefficient of the contact surface is important to understand principles of transition and suppress transitions in electromagnetic launches. In this paper, special designed armature, which makes the wear on armature contact surface all melt wear, is used in rail launch experiments to measure the wear rate of melt wear and the effects of loading on wear. Launch experiment results show that the wear rate is represented by the average thickness of the aluminum debris left on the rail. The average wear rate is about 0.6 to 2 mm/m and the average debris thickness is in a range of 3-10 um in the experiments. Based on the idea of melt wear is the main part, the heat balance of armature contact surface in launch process was analyzed. It is concluded that melt-wear absorbs mounts of heat generated on the surface, and the left heat goes into rails through the contact. The heat balance based equations was then derived, which established relationship among melt wear, launch parameters and material parameters. By the equations obtained, and using the data of launch experiments, the contact resistance of armatures with 80 mm² contact area is 2.5564μΩ, the contact resistance of armatures with 50 mm² contact area is 4.0902 μΩ and the sliding friction coefficient is 0.1131.