Reduction of Heat Transfer to Gun Barrels by Wear-Reducing Additives

Heat transfer measurements were made in a 37-mm gun equipped with thermocouples at a series of axial and radial positions. The heat transferred to the gun barrel was markedly decreased when wear-reducing additives such as polyurethane foam, titanium dioxide/wax, and talc/wax were used as liners wrapped around the gun propellant. The reduction in heat transfer was greatest when the additives were folded over the forward end of the propellant at the base of the projectile. For a given configuration, all three additives tested reduced heat transfer to the gun barrel equally. This contradicts conclusions reached in full-scale tank-cannon firing tests that TiO₂/wax and talc/wax are superior to polyurethane foam as erosion reducing additives. In these firings only the metal-oxide/wax liners had flaps folded over the forward end of the propelling charge.