Kien-Yin Lee

3-Nitro-1,2,4-triazol-5-one, a less sensitive explosive

A less sensitive explosive, 3-nitro-1,2,4-triazol-5-one. The compound 3-nitro-1,2,4-triazol-5-one (NTO) has a crystal density of 1.93 g/cm3 and calculated detonation velocity and pressure equivalent to those of RDX. It can be prepared in high yield from inexpensive starting materials in a safe synthesis. Results from initial small-scale sensitivity tests indicate that NTO is less sensitive than RDX and HMX in all respects. A 4.13 cm diameter, unconfined plate-dent test at 92% of crystal density gave the detonation pressure predicted for NTO by the BKW calculation.

An improved synthesis of 5-amino-3-nitro-1H-1,2,4-triazole (ANTA), a useful intermediate for the preparation of insensitive high explosives

Abstract Treatment of the ammonium salt of 3,5-dinitro-1H-1,2,4-triazole (ADNT) with hydrazine hydrate gives 5-amino-3-nitro-1H-1,2,4-triazole (ANTA) in greater than 90% yields. In addition to its potential use as an insensitive high explosive, ANTA has been shown to be a useful intermediate for the preparation of other explosives.

Binary eutectics formed between ammonium nitrate and amine salts of 5-nitrotetrazole I. preparation and initial characterization

Abstract We have found that both the ammonium salt of 5-nitrotetrazole (ANT) and the ethylenediamine salt of 5-nitrotetrazole (ENT) form eutectics with ammonium nitrate (AN). Initial characterization and small-scale sensitivity tests of CO2-balanced AN/ANT and AN/ENT formulations were performed; it was found that both eutectics were less sensitive in all tests than pure ANT or ENT, respectively. The phase diagrams of both mixtures were also determined. ANT forms a eutectic with AN that melts at 121°C; the eutectic composition of the AN/ANT system is 78.5 mol% AN. The eutectic temperature and composition of the AN/ENT system were found to be 110.5°C and 87.8 mol% AN, respectively. Thermal stability studies of the eutectics indicate that they are stable below 160°C and that thermal decomposition occurs slowly over a long period of time. The detonation velocities of both eutectics, measured unconfined at 2.54-cm diameter, were found to be within 95% of those predicted by the Kamlet-Jacobs method assuming ide...

Submicron-Sized Gamma-HMX: 1. Preparation and Initial Characterization

As part of our ongoing nanotechnology research effort, we have developed a novel method for the preparation of submicron-sized HMX (sm-HMX) by a simple fast-cooling technique. Surface structure analysis of the sm-HMX by field emission scanning electron microscopy reveals particles that are oblong in shape with average width of ∼ 300 nm and length of ∼ 1–2 µm. Raman spectroscopic features in the 200–2000 cm−1 range and high-intensity powder neutron diffraction were used to determine the crystallographic polymorph of the sm-HMX. Comparison of the Raman spectrum and the neutron powder diffraction pattern of sm-HMX to literature data show that sm-HMX is the gamma polymorph. The Raman data also illustrate that the polymorphic purity of the gamma sm-HMX produced by our method is greater than 99%.

Second-harmonic generation and the shock sensitivity of TATB

The recent discovery of significant differences in second-harmonic generation (SHG) from various grades of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) prompted an investigation into the sensitivity of TATB based upon the crystal structure and morphology as indicated by SHG intensity. The Floret test was used as a means for rank ordering the shock sensitivity properties of fine TATB samples. Two types of TATB, which showed low SHG and performed poorly, were heated to obtain a much higher level of SHG, and then tested to compare sensitivities. One of the samples was significantly desensitized, and the sensitivity of the other was unchanged. Interpretations are presented which attempt to explain the relationship of SHG to the shock sensitivity of TATB. Although particle size and pressing density appear to be the main drivers for shock sensitivity, SHG intensity evaluations may help explain departures from those trends.

Submicron-Sized Gamma-HMX: II. Effect of Pressing on Phase Transition

In a previous article we described the preparation and initial characterization of a novel submicron-sized HMX (sm-HMX). Using Raman spectroscopy, the sm-HMX was found to be the gamma polymorph and to be stable with respect to conversion to beta-HMX under ambient conditions for at least a year. Pressing of sm-HMX powder in a small diameter pellet press at pressures from 10,000 to 31,000 psi and 1- to 5-min hold times was found to promote the gamma-to-beta polymorphic phase transition. The fraction converted and rate of conversion versus time after pellet removal from the press were found to fit a sigmoidal curve, indicating nucleation and growth as a possible polymorphic transition mechanism.

THE EVOLUTION OF SENSITIVITY IN HMX‐BASED EXPLOSIVES DURING THE REVERSION FROM DELTA TO BETA PHASE

In an effort to better understand the evolution of sensitivity in HMX‐based explosives formulations during the reversion from the delta to the beta polymorph, we have performed friction and impact experiments on Class 1 (coarse) and Class 2 (fine) HMX [1]. Initial baselines for Type 12 drop weight impact and BAM friction sensitivities were obtained for the β‐HMX starting material. The HMX was then heated at ∼184 °C for 14 h. Raman spectroscopy was used to confirm the conversion to delta‐phase. Raman results show that the δ material remains δ for long periods when stored in a dessicator at room temperature (RT), converts to alpha when stored at RT and 20–40% relative humidity (RH) over a period of days, and reverts to beta over a period of days when stored at RT and 95–98% relative humidity (RH). Impact and friction tests were performed on the δ‐HMX, converted α‐HMX, and reverted β‐HMX. The tests show similar sensitivities of the δ‐HMX and converted α‐HMX in both impact and friction, both of which are ∼10–...

Instrumented Floret Tests of Detonation Spreading

The floret test was originally devised to permit comparison of detonation‐spreading performance of various insensitive explosive materials, using only the dent in a copper witness plate as a metric. Dent depth in the copper plate is directly related to the fraction of a thin acceptor pellet that was detonated by impact of a small explosive‐driven flyer plate. We have now added instrumentation to quantitatively measure the detonation corner‐turning behavior of IHEs. Results of multi‐fiber optical probe measurements are shown for LLM‐105 and UF‐TATB explosive materials. Results are interpreted and compared with predictions from one reaction‐rate model used to describe detonation spreading, and may be advantageous for comparison with other reactive‐flow wave‐code models. Detonation spreading in UF‐TATB occurred with formation of a non‐detonating region surrounding a detonating core, and re‐establishment of detonation in a “lateral” direction beyond that region.

Study of chemical reactions under the influence of ultrasound

At Los Alamos the author is interested in sonochemistry because there is potential for accelerating reactions involving the synthesis of certain nitro compounds and for reducing the possibility of decomposition under milder reaction conditions. The author has initiated the study of the nitration of 2,4-dihydro-3H-1,2,4-triazol-3-one with concentrated nitric acid under sonication. The preparation of 3,6-bis(3,5-dimethylpyrazol-1-yl)-1,2-dihydro-1,2,4,5-tetrazine, and oxidation of 3,6-diamino-1,2,4,5-tetrazine were also studied. Sonication reaction conditions and results of these reactions under ultrasound are discussed in detail.

Preparation and Characterization of Fine‐Particle NTO and Its Formulation with Al Nanopowders

We have initiated study of the effect of nano‐aluminum on the detonation performance of NTO. A novel method for the preparation of both fine‐particle NTO (UF‐NTO) and its formulation with Al nanopowder has been developed. Results from small‐scale sensitivity tests on both the UF‐NTO and aluminized NTO composite indicated that they are insensitive to impact, friction and HESD. The performance of both UF‐NTO and NTO/Al mix was evaluated by detonation‐spreading floret tests. At the same pressed density, it was found that, when initiated by a 3‐mm‐diameter flyer plate, the aluminized NTO composite produced a shallower dent on a copper witness plate than neat UF‐NTO and thus was inferior to UF‐NTO in detonation spreading.