CHNO-explosive

Kamlet, M. J. und Jacobs, S. J. Chemistry of Detonations, a Simple Method for Calculating Detonation Properties of CHNO-Explosives, Journal of Chem. Phys. 48, 23-50 (1968)... 

Nonideal Detonation in a Composite CHNO Explosive Containing Aluminum. 

Table 9.2 Assumed reaction products and parameters of CHNO explosives.

Keshavard, M. H., and Pouretedal, H. R., Predicting the Detonation Velocity of CHNO Explosives by a Simple Method, Propellants, Explosives, Pyrotechnics, Vol. 30, 2005, pp. 105-108. 

To obtain the true value of the heat of detonation one must know the composition of the detonation products at C-J conditions. At present such compositions can be obtained only by theoretical calculations. These calculations depend strongly on the choice of the equation of state of the detonation products. For military CHNO explosives the main equilibria that determine product composition are (Ref 9) ... 

For a quick approximate computation of the heat of detonation of military CHNO explosives, the following is suggested (Ref 9) for obtaining an approximate product composition ... 

Figure 4.1 shows the influence of the oxygen balance on conventional CHNO-explosives. Usually (this is the case for very nitrogen-rich compounds as well) a good oxygen balance results in a greater (more negative) heat of explosion and therefore leads to a better performance of the explosive. 

As mentioned previously, most explosives consist of carbon, hydrogen, nitrogen, and oxygen and are called CHNO explosives. The general formula for all CHNO explosives is expressed as where x, y, w, and z are the number of... 

This set of rules is called the simple product hierarchy for CHNO explosives (and propellants). If the explosive had contained any metal additives, these would probably not oxidize until all the above oxidation steps were completed. By traces of NO, we mean less than 1%. An example of this is TNT, detonated in the open air, where measurements have shown from 0.2 to 0.5% total NO in the original undiluted products. Of this NO, approximately half was NO. Some examples of oxidizing reactions are shown in Figures 2.3, 2.4, and 2.5. 

Table 2.1 Atomic Weights for Elements in CHNO Explosives...

This method assumes a different hierarchy of formation of product species from the detonation reaction of a CHNO explosive than the hierarchy used earlier, where CO is assumed to be formed preferentially prior to the formation of CO2. Here, with the Kamlet-Jacobs method, CO2 is assumed to be formed as the only oxidation product of carbon. As with the previous hierarchy assumptions, water is still formed first. The generalized reaction for an underoxidized explosive can be written as ... 

The differences between the calculated and measured values may in part be explained by the small diameter, confinement, and the assumptions made in the derivation of the formula for pressure which applies to CHNO explosives, not necessarily azides. 

In order to gain some insight into the chemical processes leading to initiation of detonation in solid explosives, recovery experiments have been carried out in which a solid CHNO explosive is subjected to subcritical-shocks and then analyzed for evidence of reaction [106, 107]. The results show that some chemical reaction has taken place, but the decomposition fragments have not yet been identified. Moreover, inorganic azides have not yet been studied in this manner. 

It has been customary to circumvent these questions via the convenient cal-culational technique of calibrating an a posteriori-iyi Q EOS, once its form has been chosen. Surprisingly, in spite of the uncertainties mentioned, C-J predictions of the detonation velocities of a variety of ideal (fast-acting, infinite diameter ) CHNO explosives have been rather good, within 3-5% of experimental values. For the heavy-metal azides, however, only a few C-J calculations have been reported, and the predictions are only marginally acceptable. 

Of interest are some correlations which Cook tentatively established between theoretical detonation and explosion results and the practical performance of explosives. For a group of primary and near-primary explosives (lead azide, mercury fulminate, and six CHNO explosives), he found a correlation between the probable order of ease of transition from deflagration to detonation and adiabatic explosion temperature. Moreover, he noted a rough correlation between the effectiveness of a primary explosive as a detonator (its ability to transfer detonation to a secondary explosive) and the C-J pressure [130]. 

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