SECONDARY EXPLOSIVES

If a delay and/or relay is not used in the explosive train, the explosive most often following the primer is a booster, which is a secondary explosive. The booster is less sensitive to initiation than the primer but is more sensitive than the main or, as it is sometimes called, bursting charge. The booster's role is to add detonation energy to that of the primer, thus bringing it up to a level sufficient to initiate the main charge.

Both the booster and the main charge are secondary explosives. As a secondary explosive they differ from primary explosives in three basic ways. The first is the secondary explosive's insensitivity relative to the primary explosive. In other words, it takes more initiation energy to get secondary explosives to detonate than it does primary explosives. A second difference is that secondary explosives do not normally undergo a DDT (remember: a deflagration to detonation transfer). Secondary explosive's relative insensitivity to ignition by electrostatic spark is the third difference between secondary and primary explosives.

There is an extremely large range of energetic materials that fall into the category of secondary explosives, too many to list all of them. In general, however, secondary explosives can be divided into seven basic groups. Each group and examples of representative explosives are listed below.

 

 

Aliphatic Nitrate Esters:

nitroglycerin

PETN

 

 

Nitramines:

HMX

RDX

tetryl

 

 

Nitroaromatics:

ammonium picrate

TNT

Ammonium Nitrate

 

Binary:

amatol

C4

Ternary

Quaternary