SBIR-STTR Award

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.

Benefit:
In addition to producing rails for railguns for all the military services, refractory metal coated copper base materials have applications to any electro-mechanical high heat, stress and current carrying requirement, high-speed maglev contacts, electrical generation facilities, high current switches, arc based electrodes and erosion resistant electrical contacts.

Keywords:
rail, rail, Electromagnetic, wear, Launcher, conductor, Railgun, Refractory

An electromagnetic launcher also known as a rail gun is a major gun system the Navy is developing for long range fire support. A refractory metal cladding on a copper rail is enabling for the successful high fire rate and long life of the electromagnetic launcher. Heretofore, a successful process for adherently cladding/coating a refractory metal onto a copper rail that withstands the rigors of an electromagnetic launcher has not been demonstrated. In Phase I it was demonstrated a plasma transferred arc (PTA) process was capable of producing a refractory metal clad copper gun rail which withstood bending and thermal shock testing. The Phase II is to further develop PTA cladding processing and produce experimental gun rails for multiple shot testing at the University of Texas. The PTA system is capable of processing non-planer gun rail cross-sections in continuous lengths which will also be demonstrated in the Phase II program.

Benefit:
In addition to gun rails, refractory metal clad copper has potential applications of high speed mag-lev contacts, high current switches, and electrical generating facilities.

Keywords:
plasma transferred arc, Refractory Metal Coated Copper, electromagnetic launchers, Rail Guns, Molten Metal Deposition