The reduction of barrel erosion by wear-reducing additives

Abstract

Abstract Wear-reducing liners such as polyurethane foam and TiO 2 -wax liners have markedly extended the useful life of 105 mm tank cannons. The wear life of 100 rounds without additives has been extended to 400 rounds with polyurethane foam and 10000 rounds with TiO 2 -wax liners in a flapped configuration suggested by the Swedish inventors of the TiO 2 -wax liner. When the TiO 2 -wax liner is placed in fin-stabilized rounds the liner is glued to the cartridge case wall without the flaps; the presence of fins precludes any other modification. The TiO 2 -wax liner in the fin-stabilized round improves cannon life from 100 to 1000 rounds. To discern the differences observed for the liners heat transfer measurements were made with thermocouples embedded in the barrel wall to within a millimeter of the bore surface. The reduction in heat transfer relative to standard rounds with the additives removed showed that the flapped configuration is more efficient than simply lining the case wall. In repeated firings of rounds with TiO 2 -wax additives it was observed that the heat input to the barrel steadily decreased during the first 13 rounds fired after which the heat input remained steady. This is attributed to the formation of an insulating layer on the bore surface and accounts for the higher wear life of the TiO 2 -wax liner relative to the polyurethane foam liner when used in the same configuration. It was also demonstrated that a talc-wax liner with the same dimensions as a TiO 2 -wax liner should produce improved wear life for finstabilized projectiles fired from the 105 mm tank cannon.