HMX detonation

Both RDX and HMX are stable, crystalline soHds, somewhat less sensitive to impact than PETN. Both may be handled with no physiological effect if appropriate precautions are taken to assure cleanliness of operations. Both RDX and HMX detonate to form mostiy gaseous, low molecular weight products and some intermediate formation of soHd carbons. The calculated molar detonation products of RDX are 3.00 H2O, 3.00 N2, 1.49 CO2, and 0.02 CO. RDX has been stored for as long as 10 months at 85°C without perceptible deterioration. 

Picric acid and tetryl, both yellow powders, are no longer used by the military, though do-it-yourself books outline the synthesis of picric acid for the would-be criminal/terrorist and tetryl is still found in old munitions. Most of the military explosives are white-colored powders (TNT is cream colored). Since all, but TNT, decompose upon or instead of melting, they require some sort of compounding in order to be shapeable. They can be blended into TNT in a variety of ratios to make the formulations listed in Table 2.3. They can also be formulated in wax or plasticizer. The use of plasticizer is preferred because less dilution of the explosive occurs. (In the world of performance, TNT, with detonation velocity of 6900 m/s is considered a dilutant of HMX, detonation velocity of 9100 m/s.)... 

A one-dimensional model of layers of explosive and metal with dimensions appropriate to the size of the metal particles was considered. For the explosive system of HMX with tungsten, the C-J pressure of HMX is 395 kbar and velocity is 0.9159 cm//its. The HMX detonation will interact with a tungsten plate forming a shock of 668 kbar and 830 K, moving at 0.495 cm///s. A 65/35 volume percent HMX/tungsten system in layers would have a velocity of about 0.77 cm//ns. This velocity is much higher than the experimental value of 0.5 cm//Lis. 

Three-dimensional calculations of a detonation wave in HMX interacting with a matrix of particles showed the detonation wave propagating between the particles at the C-J detonation velocity with the actual velocity determined by the shortest path through the particles. This effective velocity was less than the HMX detonation velocity and greater than the one-dimensional layer model velocity discussed earlier. The explosive shock pressures were C-J or even higher from the shock interaction with the tungsten and colliding detonation waves. 

Only relatively few compounds can act as primary explosives and still meet the restrictive military and industrial requirements for reflabiUty, ease of manufacture, low cost, compatibiUty, and long-term storage stabiUty under adverse environmental conditions. Most initiator explosives are dense, metaHoorganic compounds. In the United States, the most commonly used explosives for detonators include lead azide, PETN, and HMX. 2,4,6-Triamino-l,3,5-triuitrobenzene (TATB) is also used in electric detonators specially designed for use where stabiUty at elevated temperatures is essential. 

HMX, the highest density and highest energy soHd explosive produced on a large scale, primarily for military use, exists in four polymorphic forms. The beta form is the least sensitive, most stable, and the type requited for military use. The mole fraction products of detonation of HMX in a calorimetric bomb are 3.68 N2, 3.18 H2, 1.92 CO2, 1.06 CO, 0.97 C, 0.395 NH3, and 0.30 H2. 

Calculated relative energy of explosive released on detonation and subsequent expansion of detonation gases relative to HMX. 

RDX and Nitrocellulose, no detonation occured. Similar experience has been reported at the US Naval Ordnance Station, Indian Head, Md (Ref 3) in over 100 irradiations with 40mg samples of RDX, HMX, anhydrous hydrazine and composite propints... 

Thus it can be seen that continuous improvements in defensive armor require ever more sophisticated expl technology for its defeat, which in turn results in the escalation of military budgets for conventional warfare. The increased cost of HMX relative to other expls has caused continuing efforts to reduce manufg costs, to improve and more precisely evaluate its effectiveness. In a recent, very painstaking comparison of Cyclotol and Octol, the effects of changes in the compn, density, and diameter of the expl charge upon detonation velocity were determined. HMX was found more ef-... 

Development work by the US Navy has included attempts to use expls other than RDX and HMX viz, HNS and TACOT (Tetranitro-1,2,5,6-tetraazadibenzocyclooctatetrene) together with binders such as RTV silicon rubbers. As reported by Stott (Ref 43) such work was not fruitful because of the low deton vel and d of the developed compns... 

Threshold shock pressures to initiate detonation in several SP are shown in Table 55. In general, unless the SP contains solid HE ingredients such as HMX or RDX, the threshold pressures are considerably greater than for solid HE at a comparable degree of compaction. Even so, the pseudo-composites of AP/wax must be considered to be rather shock-sensitive provided their degree of compaction does not exceed about 90% of their theoretical max density (TMD), Figure 21 shows that up to about 90% TMD the shock sensitivity of an 80/20 AP/wax composite is very similar to that of TNT... 

This nitrimine, the nominal monomer of the cyclic nitramine high explosives RDX and HMX, may be involved in their detonation and can be formed from them by pyrolysis. 

A summary of our results on the phase diagram of water is shown in Figure 8. We find that the molecular to non-molecular transition in water occurs in the neighborhood of the estimated ZND state of HMX. This transition shows that the detonation of typical energetic materials occurs in the neighborhood of the molecular to non-molecular transition. 

Although RDX and HMX are adequate for military applications, they are by no means perfect. The risk of premature detonation increases when such explosives are used in shells for high calibre guns due to the higher set-back force. Also of concern is the risk of catastrophic... 

Heat of formation and density calculations correlate so well with performance parameter like detonation velocity that chemists have a good idea of the performance of an energetic material before its synthesis and testing. The pyrazolo[4,3-c]pyrazoles DNPP (9) and LLM-119 (10) were predicted to exhibit performances equal to 85 % and 104 % relative to that of HMX. 

The physicochemical properties of explosives are fundamentally equivalent to those of propellants. Explosives are also made of energetic materials such as nitropolymers and composite materials composed of crystalline particles and polymeric materials. TNT, RDX, and HMX are typical energetic crystalline materials used as explosives. Furthermore, when ammonium nitrate (AN) particles are mixed with an oil, an energetic explosive named ANFO (ammonium nitrate fuel oil) is formed. AN with water is also an explosive, named slurry explosive, used in industrial and civil engineering. A difference between the materials used as explosives and propellants is not readily evident. Propellants can be detonated when they are subjected to excess heat energy or mechanical shock. Explosives can be deflagrated steadily without a detonation wave when they are gently heated without mechanical shock. 

Table 9.3 shows the measured detonation velocities and densities of various types of energetic explosive materials based on the data in Refs. [9-11]. The detonation velocity at the CJ point is computed by means of Eq. (9.7). The detonation velocity increases with increasing density, as does the heat of explosion. Ammonium ni-trate(AN) is an oxidizer-rich material and its adiabatic flame temperature is low compared with that of other materials. Thus, the detonation velocity is low and hence the detonation pressure at the CJ point is low compared with that of other energetic materials. However, when AN particles are mixed with a fuel component, the detonation velocity increases. On the other hand, when HMX or RDX is mixed with a fuel component, the detonation velocity decreases because HMX and RDX are stoichiometrically balanced materials and the incorporation of fuel components decreases their adiabatic flame temperatures. 

In general, PBX materials are used for the warheads of rockets and guns. Thus, the detonation pressure pj represented by Eq. (9.7) is the most important parameter above all others. Since the detonation velocity Wj, can be measured more easily and more accurately than pj, performance is evaluated by measuring Wp, which is converted into pj by means of Eq. (9.7). Table 9.6 shows Wj, and p data, along with computed detonation pressures at the CJ point, for various HMX-PBX and RDX-PBXmaterials. 

As shown in Table 9.6, the detonation velocity is highly dependent on the density of the PBX, which, in turn, depends on the mass fraction of HMX or RDX.PB When a mixture of nylon powder and HMX particles is pressed into an explosive of the desired shape, a high-density HMX-PBX is formed. However, during the formulation process, the material is sensitive to pressurization and to mechanical shock. 

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