Demonstration of the B4C/NaIO4/PTFE Delay in the U.S. Army Hand-Held Signal

A pyrotechnic time delay based on boron carbide has been demonstrated as a viable replacement for the perchlorate- and chromate-containing formulation currently used in U.S. Army hand-held signals. Tests involving fully assembled hand-held signal rockets were conducted to evaluate the characteristics of the B4C/NaIO4/PTFE delay system in an operational configuration. The delay times observed in such dynamic tests were substantially shorter than those expected from prior static testing, necessitating the use of very slow-burning compositions to achieve the desired 5–6 s dynamic delay time. The behavior of the system at extreme temperatures (−54 and +71 °C) was also evaluated, confirming its reliability and safety. Impact, friction, and electrostatic discharge tests have shown that the boron carbide-based delay is insensitive to unintended ignition. TGA/DSC analysis indicated an ignition temperature of 475 °C, well above the decomposition temperature of NaIO4 and above the melting points of NaIO3 and PTFE.