Thermoelectrically Modulatede/Nanoscale Multilayered Gradient Materials for Application in the Electromagnetic Gun Systems

Analysis of fired rails from electromagnetic railguns indicates severe surface damage occurs due to high current arcing and tribological mismatch. We have explored the behavior of several nanoscale multilayered materials as possible routes to improve the thermomechanical properties of the rail and armature materials Structures investigated include (i) Ti–Co alloy on Ta–Cu alloy on die (diamond–like carbon) on stainless steel; (ii) Ti–Co alloy on Ta–Cu alloy on die on Cu, (iii) Ti–Co alloy on Ta–Cu on Cu; and (iv) Ti–Co on Ta–Cu alloy on Al. The alloys were all 50:50 at% and film thicknesses were in the range 400–1000 A. The films were formed using a repetitively pulsed vacuum arc plasma deposition method with substrate biasing– and IBAD–like techniques. The surfaces were characterized by scanning electron microscopy, transmission electron microscopy, Rutherford backscattering spectroscopy, optical microscopy, microhardness measurements, arc erosion resistance and scratch resistance tests. Preliminary results show improvement in the microhardness, arc erosion resistance and scratch resistance, most especially for the dlc–coated surfaces. This kind of multilayered approach to the fabrication of electromagnetic railgun and armature surfaces could be important for future advanced Electromagnetic EM Gun systems.