AP pyrolant

A mixture of B and AP particles formulates an energetic B-AP pyrolant. A small amount of polymeric material is added to serve as a binder of the B and AP parti-... 

B-AP pyrolants made with CTPB are cured with epoxy resin as in the case of conventional AP-CTPB composite propellants. The mixture ratio of large-sized AP particles (200 pm in diameter) and small-sized particles (20 pm in diameter) is 0.30/ 0.70. The mass fraction of boron is variously 0.010, 0.050, 0.075, or 0.150, and the diameter of the boron particles, d, is either 0.5 pm, 2.7 pm, or 9 pm. 

Fig. 11.12 shows a comparison of the burning rates of B-AP and Al-AP pyrolant-sas a function of pressure. In analogy to the B-AP pyrolants, the burning rates of the Al-AP pyrolants increase with increasing and with decreasing size of the alum-... 

Fig. n.l3 Temperature profiles in the combustion waves of AP pyrolants with and without boron particles. 

Fig. n.15 Burning rate augmentation as a function of pressure for B-AP pyrolants containing different mass fractions of boron particles. 

Fig. 11.16 Burning rate augmentation as a function of the total surface area of the boron particles in B-AP pyrolants composed of boron particles of different sizes.

Fig. 11.17 shows burning rate augmentation, Eb, as a function of the adiabatic flame temperatures of B-AP and Al-AP pyrolants. The incorporahon of aluminum particles into a base matrix composed of AP-CTPB pyrolant increases Ej. However, the effect of the addihon becomes saturated for adiabahc flame temperatures higher than about 2500 K. On the other hand, the incorporahon of boron particles into the same base matrix increases Eg more effectively, even though the adiabahc... 

Fig. 11.18 shows experimental results concerning the frichon sensihvity of mixtures of AP parhcles and catalysts.Iil The AP parhcles are trimodal mixtures with diameters of 200 pm (33%), 35 pm (33%), and 5 pm (34%). Catocene (C27H32pe2) and ferrocene (CjoHjoFe) are both liquid organic compounds with iron atoms in their molecular structures and carborane is a liquid compound that contains boron atoms.Ii] The physicochemical properhes of -hexyl carborane are shown in Table 11.7. These catalysts are used to increase the burning rate of AP pyrolants. 

Fig. 11.20 shows the burning rates of an AP pyrolant without a catalyst and with 5 % of three different catalysts. Catocene is seen to be the most effective catalyst for increasing the burning rate as compared with iron acetate and carborane. The burning rate is increased threefold from 5 mm s to 15 mm s" at 1 MPa and the... 

Fig. 11.21 shows the results of TG and DTA measurements on mixtures of AP particles and catalysts. The endothermic peak observed at 513 K is caused by the crystal structure transformation of AP from orthorhombic to cubic. A two-stage exothermic decomposition occurs in the range 573-720 K. The decomposition of the AP is seen to be drastically accelerated by the addition of catocene. The exothermic peak accompanied by mass loss occurs before the AP crystal transformation. Although the AP is sensitized by the addition of carborane, no effect is seen on the AP decomposition. The results indicate that carborane acts as a fuel component in the gas phase but does not catalyze the decomposition of AP. Thus, the critical friction energy is lowered due to the increased reaction rate in the gas phase. The results imply that the initiation of ignition by friction is caused by the ignition of the gaseous products of the AP pyrolants.PI... 

A mixture of ammonium perchlorate (AP NH4CIO4) and a hydrocarbon polymer (BDR) used as fuel binder forms an AP pyrolant that generates white smoke when it burns in a humid atmosphere. The polymer acts as a binder of the AP particles to form a rubber-like material. When the AP pyrolant burns, the AP particles oxidize the hydrocarbon polymer according to ... 

Combustion with complete gasification occurs when an AP pyrolant is composed of l2ip(0.86) and bi3I((0.14). The mass fraction of hydrogen chloride (HCl) among the combustion products is about 0.3. It is well known that HCl molecules combine with water vapor in the atmosphere to generate a white smoke. It is for this reason that AP pyrolants act as white smoke generators in a humid atmosphere. 

When fine aluminum particles are incorporated into AP pyrolants, aluminum oxide (AI2O3) particles are formed when they bum. Dispersal of these aluminum oxide particles in the atmosphere generates white smoke even when the atmosphere is dry. The mass fraction of aluminum particles added is approximately 0.2 for the complete combustion of AP pyrolants. Though an excess of aluminum... 

The burning rates of AN pyrolants are of the order of 1-3 mm s" at 10 MPa, which is very slow compared with AP pyrolants. Decomposition catalysts for AN powder, such as chromium trioxide (Cr203) and ammonium dichro-mate((NH4)2Cr207), need to be incorporated into AN pyrolants to aid their successive burning. Very unstable burning occurs without these catalysts. 

Typical gas-generating pyrolants include (1) AP pyrolant composed of AP, ap(0.50), and HTPB, htpb(0-50), which is cured with isophorone diisocy-anate(lPDl) (2) NP pyrolant composed of NC, nc(0-70) and NG, ng(0-30), which is plasticized with diethyl phthalate (DEP) and (3) GAP pyrolant composed of gly-cidyl azide copolymer, qap(0-85), which is cured with hexamethylene diisocy-anate(HMDl) and cross-linked with trimethylolpropane (TMP). 

The specific impulse of each pyrolant is computed as a function of air-to-fuel ratio, as shown in Fig. 15.7. In the computations, the pressure in the ramburner is assumed to be 0.6 MPa at Mach number 2.0for a sea-level flight When GAP pyrolant is used as a gas-generating pyrolant, the specific impulse is approximately 800 s at e = 10. It is evident that AP pyrolant and NP pyrolant are not favorable for use as gas-generating pyrolants in VFDR. However, the specific impulse and burning rate characteristics of these pyrolants are further improved by the addition of energetic materials and burning rate modifiers. 

The adiabatic flame temperature, 7, is 2220 K at (0.0), i. e., without B or A1 particles. 7 remains relatively unchanged in the region of less than 0.05, but then rises to a maximum of 2260 K at b(0.15). On the other hand, when A1 is mixed with AP, 7 reaches a maximum of3000 K at Ai(flT8). The maximum flame temperature of a B-AP pyrolant is thus approximately 740 K lower than that of an Al-AP py-rolant.[i7]... 

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