Burning mechanism and regression rate of RX-35-AU and RX-35-AV as a function of HMX particle size measured by the hybrid closed bomb-strand burner

Conference · Sun Apr 01 00:00:00 EST 1990

OSTI ID:6922864

Tao, W C; Costantino, M S; Ornellas, D L

In this study, the average surface regression rate of two HMX-based cast explosives, RX-35-AU and RX-35-AV, is measured to pressures above 750 MPa using a hybrid closed bomb-strand burner. The hybrid design allows the simultaneous measurement of pressure and regression rate over a large range of pressures in each experiment. Nitroglycerin/Triacetin (75/25) and polyethylene glycol (PEG) are used as the energetic plasticizer and polymeric binder, respectively, in both formulations. The HMX solids loading in each formulation is 50 wt %, consisting of a narrow particle size distribution of 6--8 {mu}m for RX-35-AU and 150--177 {mu}m for RX-35-AV. Of special interest are the regression rate and burning mechanism as a function of the initial particle size distribution and the mechanical properties fo the cast explosives. In general, the regression rate for the larger particle size formulation, RX-35-AV, is two to three times faster compared to that for RX-35-AU. Up to 750 MPa and independent of the initial confinement pressure, RX-35-AU exhibits a planar burning mechanism with the regression rate obeying the classical aP{sup n} formalism. For RX-35-AV, however, the burning behavior is erratic for samples ignited at 200 MPa confinement pressure. At confinement pressures above 400 MPa, the regression exhibits more of a planar burning mechanism. The unstable combustion behavior for RX-35-AV at lower confinement pressures is related to several mechanisms: (1) an abrupt increase in surface area due to particle fracture and subsequent translation and rotation, resulting in debonding and creating porosity, (2) thixotropic'' separation of the binder and nitramine, causing the significantly greater fracture damage to the nitramine during the loading cycle, (3) microscopic damage to the nitramine crystals that increase its intrinsic burning rate. 12 refs., 8 figs., 2 tabs.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
• Sponsoring Organization: DOE/DP
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6922864
• Report Number(s): UCRL-102578; CONF-9004147-5; ON: DE90010677
• Resource Relation: Conference: 1990 JANNAF propulsion systems hazards meeting, Laurel, MD (USA), 3-5 Apr 1990
• Country of Publication: United States
• Language: English

Related Subjects

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
CHEMICAL EXPLOSIVES
COMBUSTION KINETICS
NITRO COMPOUNDS
BURNERS
COMBUSTION
PARTICLE SIZE
PRESSURE EFFECTS
SURFACE AREA
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
EXPLOSIVES
KINETICS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDATION
REACTION KINETICS
SIZE
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
450100* - Military Technology
Weaponry
& National Defense- Chemical Explosions & Explosives