A Plasma Process to Apply Refractory Metal Coatings to Continuous Lengths of Copper Alloy Rails

High strength copper alloys are preferred as the base rails for railguns due to their combination of strength and electrical and thermal conductivity, but suffer damage due to high current densities, arcing, gouging, and exposure to molten aluminum armatures. A refractory metal/alloy coating on the copper base alloy is an attractive approach for increasing rail life if the refractory metal coating remains adherent and withstands the thermal transients and other phenomena that usually limit shot life. A plasma process can apply the refractory metal/alloys from a molten state that provides a functionally graded interface resulting in adhesion at least equivalent to the base copper alloy strength. The plasma coating process can produce the refractory metal/alloy-copper base in continuous length, and with arbitrary cross-sections. In a team with the University of Texas (UT), the plasma refractory metal/alloy process will produce rail coupons for railgun testing at UT and demonstration that continuous lengths are producible.