Crystal Growth of Energetic Materials during High Acceleration using an Ultracentrifuge

AbstractStudies of the growth of crystals of energetic materials under conditions of high acceleration in an ultracentrifuge are reported. When a saturated solution is accelerated in an ultracentrifuge, the solute molecules move individually through the solvent molecules to form a crystal at the outer edge of the tube if the solute is more dense than the solvent. Since there is no evaporation or temperature variation, convection currents caused by simultaneous movement of solvent and solute are minimized and crystal defects are potentially minimized. Crystal growth is controlled by the g-level of the acceleration. In addition, solution inclusions and bubbles migrate out of the saturated solution as a result of the pressure gradient induced by the g-force. We present results of TNT, RDX, and TNAZ grown at high g from various solutions.

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Mechanical Behavior of Energetic Materials during High Acceleration

10.1063/1.1483671 ◽

2002 ◽

Author(s):

Y. Lanzerotti

Keyword(s):

Mechanical Behavior ◽

Energetic Materials ◽

High Acceleration

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Chemical Reaction of Energetic Materials during High Acceleration

Shock Waves in Condensed Matter ◽

10.1007/978-1-4613-2207-8_134 ◽

1986 ◽

pp. 909-916 ◽

Cited By ~ 1

Author(s):

M. Y. D. Lanzerotti ◽

J. Pinto

Keyword(s):

Chemical Reaction ◽

Energetic Materials ◽

High Acceleration

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Mechanical Behavior of Energetic Materials at High Acceleration

Processing by Centrifugation ◽

10.1007/978-1-4615-0687-4_43 ◽

2001 ◽

pp. 367-369

Author(s):

Y. Lanzerotti ◽

J. Sharma

Keyword(s):

Mechanical Behavior ◽

Energetic Materials ◽

High Acceleration

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Density of RDX Crystals Grown During High Acceleration in an Ultracentrifuge

MRS Proceedings ◽

10.1557/proc-0896-h05-01 ◽

2005 ◽

Vol 896 ◽

Author(s):

Mary Y. D. Lanzerotti ◽

Richard Z. Squillace ◽

Alexander Gandzelko ◽

Jagadish Sharma

Keyword(s):

Crystal Growth ◽

Maximum Density ◽

Crystal Defects ◽

Commercial Grade ◽

Theoretical Maximum ◽

High Acceleration ◽

Cyclotrimethylene Trinitramine ◽

Crystal Density ◽

Defect Content ◽

Solvent Molecules

AbstractRDX (cyclotrimethylene-trinitramine) crystals were grown during high acceleration (high g) in an ultracentrifuge. These crystals are found to have a density ∼0.6% greater than 1 g crystals and to have a greatly reduced defect content. The high g crystals should therefore have significantly reduced shock sensitivity as compared to commercial grade RDX. When a RDX saturated acetone solution is accelerated at 200,000 g, the RDX solute molecules move individually through the acetone solvent molecules to form a RDX crystal because the density of the RDX (Theoretical Maximum Density 1.806 g/cc) solute is more dense than the acetone (0.79 g/cc)solvent. Crystal growth is controlled by the g-force. Crystal defects including voids and solution inclusions caused by temperature variation or evaporation at 1 g are minimized and the RDX crystal density increases. A nitrogen pycnometer was used to measure the density of the RDX crystals grown at 1 g and at 200,000 g. The density of the RDX crystals grown at 200,000 g (1.7980±0.0003 g/cc) is found to be greater than the density of RDX crystals grown at 1 g (1.7881±0.0003 g/cc) by 0.0099 g/cc. The density of the high g crystal is 99.6% of the Theoretical Maximum Density of RDX.

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Crystal growth of organic energetic materials: pentaerythritol tetranitrate

Open Engineering ◽

10.2478/s13531-012-0012-6 ◽

2012 ◽

Vol 2 (3) ◽

Cited By ~ 5

Author(s):

Gengxin Zhang ◽

Brandon Weeks ◽

Xin Zhang

Keyword(s):

Crystal Structure ◽

Thermal Stability ◽

Crystal Growth ◽

Energetic Materials ◽

Strong Dependence ◽

Energy Output ◽

Deposition Flux ◽

Strong Impact ◽

Layer By Layer ◽

Pentaerythritol Tetranitrate

AbstractThe energy output performance and thermal stability of organic energetic materials have a strong dependence on the porosity, particle morphology, and micro-scale crystal structure. This paper reviews the growth habit of pure pentaerythritol tetranitrate (PETN) crystals and the effect of metal impurities on microcrystal morphology of PETN films. The pure crystal growth shows that PETN molecules diffuse on the surface and nucleate in a two-dimensional layer-by-layer fashion; the final structure is controlled by the deposition flux. Also, the effect of metal cation impurities has a strong impact on the thermal stability and crystal structure, and is dependent on the doping level.

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AFM Studies of Fracture Surfaces of Composition B Energetic Materials

MRS Proceedings ◽

10.1557/proc-705-y7.11 ◽

2001 ◽

Vol 705 ◽

Author(s):

Y. D. Lanzerotti ◽

J. Sharma

Keyword(s):

Atomic Force Microscopy ◽

Tensile Strength ◽

Fracture Surface ◽

Surface Structure ◽

Energetic Materials ◽

Mechanical Failure ◽

Force Microscopy ◽

Atomic Force ◽

High Acceleration ◽

Columnar Grains

AbstractThe characteristics of TNT (trinitrotoluene) crystals in Composition B have been studied using atomic force microscopy (AFM). The size of TNT crystals has been examined by analyzing the surface structure that is exhibited after mechanical failure of the Composition B. The mechanical failure occurs when the material is subjected to high acceleration (high g)inan ultracentrifuge and. the shear or tensile strength is exceeded. AFM examination of the topography of the Composition B fracture surface reveals fracture across columnar grains of the TNT. The width of the columnar TNT grains ranges in size from ~ 1 μm to~2 μm. Their height ranges in size from ~ 50 nm to ~ 300 nm.

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Mechanical Behavior of Energetic Materials During High Acceleration in An Ultracentrifuge

MRS Proceedings ◽

10.1557/proc-362-131 ◽

1994 ◽

Vol 362 ◽

Author(s):

M. Yvonne D. Lanzerotti ◽

J. Sharma

Keyword(s):

Mechanical Behavior ◽

Surface Area ◽

Energetic Materials ◽

Area Ratio ◽

Crystal Defects ◽

Surface Area Ratio ◽

High Acceleration ◽

New Information ◽

Binding Surface ◽

Effective Additive

AbstractThe mechanical behavior of explosives subjected to high acceleration (high g) has been studied in an ultracentrifuge. The experiments reported here reveal new information on the mechanical behavior of such materials and the influence of grain size on the fracture process. Through measurement and analysis of fracture surfaces, we have found that predominately intergranular failure occurs when the shear or tensile strength of the explosive is exceeded. We have found that the mechanical strength of melt-cast polycrystalline TNT varies inversely with crystal size. That is, if the sample consists of large, homogeneous crystals, these are found to separate from the sample at lower g-levels due to the larger mass-to-binding surface area ratio of the crystals. Conversely, smaller original crystallites are found to separate at higher g-levets due to the smaller mass-to-binding surface area ratio. Our results show that single crystals of TNT fracture under a higher g-level at crystal defects. We have also found that the fracture acceleration of Octol decreases with increasing percent TNT and decreasing percent HMX. Hexanitrostilbene (HNS) has been shown by other investigators to be an effective additive to prevent growth of large TNT grains. We have found that the fracture acceleration increases when HNS is added to Octol.

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