RDX-CMDB propellant

When the mass fraction of AP is increased, the dark zone of the base matrix is eliminated almost completely and the luminous flame approaches the burning surface as shown in Fig. 8.2(a). For reference, the flame structure of an RDX-CMDB propellant is also shown in Fig. 8.2(b). Since RDX is a stoichiometrically balanced... 

Fig. 8.2 Flame photographs of AP-CMDB propellant (a) and RDX-CMDB propellant (b) showing that the luminous flame front of the RDX-CMDB propellant is distended from the burning surface ...

Fig. 8.6 Temperature profiles in the combustion wave structures of an RDX-CMDB propellant at different pressures.

The catalysts (lead and copper salts of aromatic acid in combination with carbon black) which were effective for DB and RDX-CMDB propellants were also found effective for dinitropiperazine (DNP) containing CMDB propellants [259]. Copper chromite (CC) and ferric oxide which are generally used for ballistic modification of composite propellants are also effective for CL-20-based aluminized CMDB propellants. However, CC is a better BRM [260]. 

Lead metal has been shown to be important in burning-rate catalysis, where it has been proposed as the effective catalytic agent in double-base propellant combustion, in which it appears to promote the rate of collapse of organic nitrates. The lead(n) salt of 3,5-dinitro-2-pyridone and lead(ii) salts derived from >-nitrocalix[n]arene (n = 4, 6, 8) (Figure 22.1) have been prepared and shown to decrease the exothermic peak temperatures and improve the decomposition heats of the explosives NC-NG and RDX, and to increase the burning rates of both DB and RDX-CMDB propellants. ... 

When nitramine particles such as HMX or RDX particles are mixed with a doublebase propellant, nitramine composite-modified double-base propellants are formulated. Since HMX and RDX are stoichiometrically balanced materials, the use of these nitramine particles leads to a somewhat different mode of combustion as compared to AP-CMDB propellants. Since each nitramine particle can burn independently of the base matrix at the burning surface, a monopropellant flamelet is formed in the gas phase from each particle. The monopropellant flamelet diffuses into the reactive gas of the base matrix above the burning surface and a homogeneously mixed gas is formed. 

Since the energy contained within double-base propellants is limited because of the limited energies of nitrocellulose (NC) and nitroglycerin (NG), the addition of ammonium perchlorate or energetic nitramine particles such as HMX and RDX increases the combustion temperature and specific impulse. Extensive experimental studies have been carried out on the combustion characteristics of composite-modified double-base (CMDB) propellants containing AP, RDX or HMX parhclesli- l and several models have been proposed to describe the burning rates of these pro-... 

The data reported in the literature suggests that the replacement of DEP by Bu-NENA in the Dense NC/NG+ DEP/AP/AI/RDX-based composite modified double-base (CMDB) propellants results in increase in the burn rate by 18-20% at 70 kg cm pressure. The calorimetric value and percentage elongation also increase significantly. Further, thermal stability and sensitivity of such propellants are comparable with DEP-based CMDB propellants [184]. Bu-NENA is also a component of low vulnerability ammunition (LOVA) propellants [185, 186]. The introduction of butyl-NENA into SB, DB and gun propellants results in improvement of their mechanical properties and energetics and reduction in their sensitivity [187]. 

A study was conducted to find out the effect of addition of these nitroplasticizers on ballistic properties of AP and RDX/HMX filled CMDB propellants. The data generated clearly indicated that the incorporation of nitroplasticizer, that is, 1 1 mixture of BDNPF and BDNPA in place of diethyl phthalate (DEP) for AP and nitramine based CMDB propellants improved the burn rates as well as /sp and thermal decomposition behavior of these propellant formulations [193]. 

Typical crystalline-energetic-particles are AP and nitramines such as HMX and RDX. The use of AP leads to an AP-CMDB propellant and the use of HMX leads to an HMX-CMDB propellant. These particles burn as a monopropellant at the burning surface of the CMDB propellant, and the combustion products react again with the combustion products of the base matrix. 

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