A new type of shell that heats up on impact to burn through steel is being developed by the US Office of Naval Research (ONR).
The projectile, which has shown potential for use against aircraft and light armour, contains a mixture of aluminium polytetrafluoroethylene (PTFE) and perchlorate oxidiser, moulded together into an aerodynamic shape.
Soft Teflon tape is wound around this substance at high tension then heated and covered with an epoxy glue, forming a covering that stops the projectile from disintegrating as it travels through the air at high speed.
The impact of the shell starts a reaction in which the chemicals produce a burst of heat strong enough to burn through armour plating. Pure Teflon shells have been available for some time, but a structural reactive material shell with Teflon as the binding material has not previously been developed beyond initial concept level.
The Teflon and perchlorate used in the shell are both oxidizers. Any metals in contact with them will react at their respective thermal decomposition temperatures; for example, aluminium would heat to around 3,500ºC.
The shells are designed to be fired using existing equipment. ‘Conventional explosives can be used to propel reactive materials containing Teflon fragments,’ said Dr. Clifford Bedford, scientific advisor at the ONR’s Air Warfare and Weapons Department.
‘The issues of drag associated with material density of the composition are, of course, a principal concern.’
‘The reactive fragment warhead has demonstrated significant effectiveness against air targets. It generally causes significant structural damage to light-skinned armour.’
The only toxic materials generated by the Teflon shell would be small quantities of low molecular-weight fluorocarbons, though full analysis of the product of the decomposition caused by the shells’ impact has not yet been conducted. But Bedford said this type of shell was not effective enough to replace depleted uranium rods used on heavy armour-piercing shells, which cause radioactive contamination of battle sites.