New pyrotechnic smoke compositions, containing only environmentally benign materials, have been demonstrated to produce thick white smoke clouds upon combustion. These compositions use powdered boron carbide (B4C) as a pyrotechnic fuel, KNO3 as a pyrotechnic oxidizer, and KCl as a combustion temperature moderator. Small amounts of calcium stearate and polymeric binders may be added to moderate burning rate and for composition granulation. Prototype tests involving three preferred compositions were conducted in end- and core-burning grenade and canister configurations. Smoke release times ranged from 3.5 to 70 s for the grenades and from 8 to 100 s for the canisters. Notably, any desired smoke release time within these ranges may be obtained by fine adjustment to the calcium stearate content of the compositions and/or small changes to the device containers. Aerosolization efficiency and quantitative performance, as determined by smoke chamber measurements, remain consistent regardless of smoke release time. Impact, friction, and electrostatic discharge tests show that the compositions are insensitive to accidental ignition and are safe to handle.

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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 B 4 C/NaIO 4 /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 slowburning 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 NaIO 4 and above the melting points of NaIO 3 and PTFE.