Catalyzed NC-NG propellant

The heat of explosion of the uncatalyzed NC-NG propellant decreases rapidly when the pressure is decreased below about 4 MPa, as shown in Fig. 13.12. However, the heat of explosion of the catalyzed NC-NG propellant remains relatively unchanged, even below 2 MPa. 

Substituting the measured H xp data into Eqs. (13.32) and (13.28), one obtains an experimentally determined m value as a function of pressure. The results indicate that m of the uncatalyzed NC-NG propellant is approximately 0.35 at 0.6 MPa, gradually decreases with increasing pressure, and becomes zero at 5 MPa and above m of the catalyzed NC-NG propellant is approximately zero over the same tested pressure range. Substituting the results for m and n into Eq. (13.35), one gets... 

The combustion tests conducted for a rocket motor show that the combustion becomes unstable below 1.7 MPa and that the burning acquires a chuffing mode in the case of the uncatalyzed propellant. However, as expected, the combustion is stable even below 0.5 MPa for the nickel-catalyzed NC-NG propellant, as shown in Fig. 13.13. Propellants for which the flame temperature decreases with decreasing pressure tend to exhibit T combustion instability. 

Fig. 6.22 shows a typical set of burning rates for catalyzed and non-catalyzed NC-NG double-base propellants. The burning rate of the non-catalyzed propellant composed of 53 % NC, 40% NG, and 7 % DEP is seen to increase linearly with increasing pres sure in an In r versus In p plot. When the propellant is catalyzed with a com-... 

Fig. 6.23 shows a comparison of the burning rates of catalyzed NC-NG and NC-TMETN propellants. As shown in Table 6.8, the chemical compositions of both propellants contain equal quantities of the same catalysts. The burning rates of the non-catalyzed NC-NG and NC-TMETN propellants are shown in Fig. 6.18. The energy densities of the two catalyzed propellants are approximately equal.

Fig. 6.23 Burning rates of catalyzed NC-NG and NC-TMETN double-base propellants, showing two platonized regions for both propellants resulting from the addition of a combination of two lead compounds.

Figure 6-22 shows a comparison of the burning rates of catalyzed NC-NG and NC-TMETN propellants. As shown in Table 6-5, the chemical compositions of both... 

Table 6.8 Chemical compositions of catalyzed NC-TMETN and NC-NG double-base propellants (% by mass).

Super-rate burning occurs when lithium fluoride (LiF) is incorporated into NC-NG or NC-TMETN double-base propellants. As shown in Fig. 6.27, the burning rate of a propellant catalyzed with 2.4% LiF and 0.1% C increases drastically in the pressure region between 0.3 MPa and 0.5 MPa. This super-rate burning effect diminishes gradually as the pressure is increased above 0.5 MPa. The non-cata-lyzed propellant is a conventional NC-NG double-base propellant composed of 55 % NC, 35% NG, and 10% DEP. The maximum burning rate increase is about 230% at 0.5 MPa. 

Like double-base propellants, CMDB propellants show super-rate and plateau burning when they are catalyzed with small amounts of lead compounds. Fig. 8.21 shows a typical plateau burning for a propellant composed of NC-NG and HMX.P I The chemical composition of the catalyzed propellant is shown in Table 8.1. 

The propellants composed of NC-NG and HMX show super-rate and plateau burning rate characteristics as shown in Fig. 6-25 201. The chemical compositions on noncatalyzed and catalyzed propellants are shown in Table 6-6. 

Fig. 6.29 shows the effect, or lack thereof, of the addihon of Ni particles on the burning rate of a double-base propellant. The double-base propellant is composed of Nc(0-44), ng(0.43), i3gp(0.11), and Iec(0-02) as a reference propellant. This propellant is catalyzed with 1.0% Ni particles (2 pm in diameter). No burning rate change is seen upon the addition of Ni particles.F However, the flame structure is altered significantly by the addition of Ni. The flame stand-off distance between the burning surface and the luminous flame front is shortened, as shown in Fig. 6.30. Though the flame stand-off distance of the reference propellant is about 8 mm at 1.5 MPa and decreases rapidly with increasing pressure (1 mm at 4.0 MPa), the flame stand-off distance of the Ni-catalyzed propellant remains unchanged (0.3 mm) when the pressure is increased.

Figure 6-31 shows the effect of the addition of Ni particles on the burning rate of a double-base propellant. The double-base propellant is composed of 44.0% NC, 43.0% NG, 11.0% DEP, and 2.0% EC as a reference propellant. This propellant is catalyzed with 1.0% Ni particles (2 pm in diameter). No burning rate change is seen on addition of Ni particles1221. However, the flame structure is altered significantly... 

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