• Journal of the Korea Institute of Military Science and Technology
• /
• v.5 no.3
• /
• pp.56-61
• /
• 2002

The hexanitrohexaazaisowurtzitane(HNIW) is a polycyclic caged nitramine oxidizer. For most existing weapons systems, the most critical ingredient in explosive and propellant applications is the oxidizer, HNIW, with its increase in performance output and energy capabilities for future in explosive and propellant systems. Two new polyacylhexaazaisowurtzitanes were synthesized. Pentaacetylhexaaza-isowurtzitane(PAIW) or pentaacetylformylhexaazaisowurtzitane(PAFIW) can be a precursor in the preparation of HNIW, recently developed highly energetic material.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.23 no.3
• /
• pp.44-50
• /
• 2019

HNIW is a high energy material and has four crystalline phases, it is known that the thermal properties of the material depend on the crystal phase. In this sturdy, the viscosity, mechanical and burning properties of a solid propellant with nitrate ester polyester(NEPE) system with respect to the crystal phases of HNIW. According to the crystal phase of HNIW, the mechanical properties of the cured propellant did not change considerably, however differences were observed in the burning properties. Considering both a high density and stable burning properties, the optimum crystal phase of HNIW can be identified as the main factor influencing to the NEPE system propellant.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.4 no.4
• /
• pp.9-17
• /
• 2000

The crystal growth and dissolution rates were calculated by solving a model equation, which involved the dissolution of the metastable phase($\beta$-HNIW) and growth of the stable phase($\varepsilon$-HNIW), together with the mass balance equation. The model has been successfully used to simulate available kinetic data for the $\beta$$\longrightarrow$$\varepsilon$ polymorphic transformation via a solution phase. From the effectiveness factor based on the two-step model, it was found that the surface integration contribution to the process was comparatively small, and a diffusion dependency decreased with an increase of the mass fraction of chloroform in the mixed solvents of ethyl acetate and chloroform. Appling these kinetics in process simulation allowed for the prediction of the product size of $\varepsilon$-HNIW.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.4
• /
• pp.12-18
• /
• 2021

This study aimed at preparing the solid propellants featuring high pressure exponent available for throttleable rocket system development. The combustion properties of solid propellant based on PCP as a prepolymer were investigated with the different nitramine oxidizer, HMX and HNIW. As a main oxidizer, HNIW could deliver higher burning rate, specific impulse and flame temperature than HMX. In addition, the introduction of AP as a co-oxidizer in PCP/Nitramine propellants could enhance burning rate, specific impulse and flame temperature, showing the lower pressure exponent with increasing the content of fine-sized AP, total solids and plasticizer. Moreover, we examined the temperature sensitivity on burning rate of propellants between 150 psia and 2,500 psia.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1996.05a
• /
• pp.121-127
• /
• 1996

To compare the performance of aluminized solid propellants, the theoretical calculation was performed for the propellants using HTPB and PEG binder and four kinds of oxidizers such as AP, HMX, ADN, and HNIW. PEG/HMX/Al and PEG/HNIW/Al showed the maximum performance at 17% of aluminum level and there was no difference in maximum performance when HMX was partially replaced with AP in PEG/HMX/AP/Al propellant. The order of performance magnitude of various propellants which the specific impulse loss calculation was considered by semi-empirical equation was like the following; PEG/HNIW/AI>[$\frac{PEG/HMX/AI}{PEG/HMX/AP/AI}$>HTPB/AP/AI>PEG/ADN/AI

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1997.11a
• /
• pp.13-13
• /
• 1997

1980년대 후반 미국 China Lake의 Naval Weapon Center에서 개발된 hexanitrohexa-azaisowurzitane(HNIW;CL-20)은 nitro group의 배향에 따라 $\alpha$, $\beta$,$\gamma$,$\varepsilon$형으로 불리우는 네 가지의 분리가능 한 polymorph가 존재하는 것으로 알려져 있다. 이중에서 $\varepsilon$형은 다른 polymorph보다 더 안정한 상으로서 고체추진제의 산화제로 사용하기에 적당한 구형에 가까운 결정모양을 가지고 있으며 밀도가 가장 크다. 제조된 HNIW 결정 중에는 소량의 $\beta$형을 함유할 수 있으므로 이의 함량을 측정하는 일은 매우 중요한 것이라 할 수 있다. 본 연구에서는 FT-IR을 이용하여 $\beta$형과 $\varepsilon$형을 가장 명확하게 구분할 수 있는 영역을 선택하고 $\varepsilon$함량에 따라 변화하는 흡광도를 plotting하여 검정곡선을 작성한 후 상호 관계를 수식으로 나타내어 HNIW 결정중의 $\varepsilon$형 함량을 결정할 수 있는 방법을 개발하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.05a
• /
• pp.383-386
• /
• 2006

Several HTPB/AP and HTPB/AP/HMX propellants were investigated experimentally for ignition characteristics in subatmospheric pressure. The threshold ignition pressure was 4psia for HTPB/AP composite propellant. The partial replacement of AP in HTPB/AP composite propellant by $5\sim15%$ of HMX, HNIW showed improvements in the threshold pressure was below 0.4psia. This appears to be due to the exothermic dissociation characteristics of HMX and HNIW at lower temperature $(\sim220^{\circ}C)$ than that of AP. The ignition substance B/KNO3 was coated thinly on the propellant surface for better ignition effect. As a result, ignition delay time of 15% was improved. NC is applied to $B/KNO_3$ ignition substance as a secondary binder and $NC-B/KNO-3$ suspension solution is coated to the propellant surface.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.3
• /
• pp.67-72
• /
• 2006

Several propellants were investigated experimentally for ignition characteristics in subatmospheric pressure. The threshold ignition pressure was 4 psia for HTPB/AP composite propellant. The partial replacement of AP in HTPB/AP propellant by $5{\sim}l5%$ of HMX, HNIW showed that the improvements in ignition delay was over 50% and the threshold pressure was below 0.4 psia. This appears to be due to the characteristics of HMX and HNIW exothermic dissociated at the temperature(${\sim}220^{\circ}C$) love. than that of AP. The ignition substance $B/KNO_3$ was coated thinly on the propellant surface for better ignition performance. As a result, ignition delay time of 15% was improved. NC is applied to $B/KNO_3$ ignition substance as a secondary binder and $NC-B/KNO_3$ suspension solution is coated to the propellant surface.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.8
• /
• pp.95-103
• /
• 2006

The compositions, the gas properties in motor chamber and the aluminum oxide (Al2O3) particle size for two kinds of solid propellants with approximately 20% aluminum powder have been investigated. The SEM photographs of $Al_2O_3$ taken from nozzle entrance liner show that the aluminized PCP propellant with 47% volumetric fraction AP/HNIW and bimodal oxidizer 200-5 ${\mu}m$ can offer greater possibility for increasing aluminum agglomeration than the aluminized HTPB propellant with 64% volumetric fraction AP and trimodal oxidizer 400-200-6 ${\mu}m$. The nozzle entrance liner of solid rocket motor with the PCP propellant shows greater erosion at 4 circumferential sections in line with grain slots due to the impingement of large particles, but that with the HTPB propellant shows uniform erosion with circumferential angle.