Cold Sprayed Liners for Gun Tubes

Abstract

The use of refractory materials is currently being developed for gun barrel coatings and liners. Explosive cladding, as well as a novel gun liner emplacement with elastomeric material (GLEEM) technique has been shown to be a successful method for bonding liners into 25-mm M242 Bushmaster barrels. The process relies on commercially available tube products that serve as the liner materials that are often difficult to manufacture. Cold spray is a novel process used to consolidate metal powders into both thin coatings and large bulk materials that is being investigated as a cost effective alternative to conventional processing techniques. This work examines the use of cold spray as it pertains to the consolidation of Ta donor tubes for explosively bonded gun liners. Ta tubes were consolidated and annealed to increase the ductility of the material from 0.2% to 35% strain as determined by tensile testing. Ta donor tube was successfully explosively clad to 25 mm gun barrel forging. Bond strength testing results of explosively clad cold spray tube were found to be comparable to commercially obtained liners. GLEEM was also successfully employed. However, the mechanical bond strength of this cladding was considerably lower than that of the explosively clad liner. The failure mechanism during GLEEM is slip between the liner and the forging and is due to the fact that the process relies on frictional bonding rather than metallurgical bonding.