Dabin Liu

Combustion heat of the Al/B powder and its application in metallized explosives in underwater explosions

An underwater explosion test is used to determine the detonation properties of metallized explosives containing aluminum and boron powders. An oxygen bomb calorimeter (PARR 6200 calorimeter, Parr Instrument Company, USA) is used to obtain the heat of combustion of the metal mixtures. As the content of boron powders is increased, the heat of combustion of the metal mixtures increases, and the combustion efficiency of boron decreases. The highest value of the combustion heat is 38.2181 MJ/kg, with the boron content of 40%. All metallized explosive compositions (RDX/Al/B/AP) have higher detonation energy (including higher shock wave energy and bubble energy) in water than the TNT charge. The highest total useful energy is 6.821 MJ/kg, with the boron content of 10%. It is 3.4% higher than the total energy of the RDX/Al/AP composition, and it is 2.1 times higher than the TNT equivalent.

Underwater Explosion Analysis of Hexogen-Enriched Novel Hydrogen Storage Alloy

A novel hydrogen storage alloy was used in hexogen-based thermobaric explosive (RDX-based TBE). Two types of fashioned explosive charges with mass of 160 g and 500 g were used in this work. The energy of TBE was tested by underwater explosion. The results indicate hexogen-enriched novel hydrogen storage alloy can produce higher bubble energy than that enriched aluminum. The total useful energy was 4.7 % (160 g) and 6.4 % (500 g) higher than an explosive with the same aluminum content, and Trotyl (TNT) equivalent of 2.1 times. The heat of explosion test shows the similar result that the novel hydrogen storage alloy can improve the total energy, about 7.9 % higher than the aluminized.

Detonation characteristics of ammonium nitrate and activated fertilizer mixtures

To better understand the detonation characteristics of ammonium nitrate (AN) and activated additives mixtures, potassium chloride (KCl) and monoammonium phosphate (MAP) are mixed with AN by different mixing methods. The UN gap test and scanning electron microscopy are applied to study AN and AN-additive mixtures. For the mechanical mixing method, the detonation velocity of AN-additives decreases with increasing the additive proportion, while the detonation velocity of modified AN prepared by the solution mixing method shows the opposite tendency. It is proved that the sensitivity to shock waves increases as the size of AN particles decreases. The type of additives, the mixing methods, and the particle size distribution are important parameters that affect the detonation characteristics of AN.

Study on Thermal Decomposition Characteristics of Ammonium Nitrate Emulsion Explosive in Different Scales

ABSTRACT Numerous accidents of emulsion explosive (EE) are attributed to uncontrolled thermal decomposition of ammonium nitrate emulsion (ANE, the intermediate of EE) and EE in large scale. In order to study the thermal decomposition characteristics of ANE and EE in different scales, a large-scale test of modified vented pipe test (MVPT), and two laboratory-scale tests of differential scanning calorimeter (DSC) and accelerating rate calorimeter (ARC) were applied in the present study. The scale effect and water effect both play an important role in the thermal stability of ANE and EE. The measured decomposition temperatures of ANE and EE in MVPT are 146°C and 144°C, respectively, much lower than those in DSC and ARC. As the size of the same sample in DSC, ARC, and MVPT successively increases, the onset temperatures decrease. In the same test, the measured onset temperature value of ANE is higher than that of EE. The water composition of the sample stabilizes the sample. The large-scale test of MVPT can provide information for the real-life operations. The large-scale operations have more risks, and continuous overheating should be avoided.

Effect of potassium chloride on thermal stability of ammonium nitrate under acidic conditions

Ammonium nitrate (AN) can decompose and further detonate under some conditions, e.g., in the presence of impurities which act as promoters. Its reactive hazards have been widely studied for several years. However, many large accidents involving AN still happened frequently in the recent years. It is found that, for accidents in storage or transportation, the thermal runaway is a major factor. The main objective of the research is to examine the effect of potassium chloride (KCl) on the thermal stability of AN under acidic conditions. The thermal stability of samples was investigated by differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC), the Cook-off test and the Dewar test. The results indicate that KCl can significantly reduce the thermal stability of AN under acidic conditions. The catalytic effect of KCl on the decomposition of AN is limited without acidic conditions. The scale effect also is important factor to influence the thermal stability of AN.

Performance of a New Composite Explosive Used in Permissible Detonators for Coal Mining

ABSTRACT A new type of composite explosive used in a permissible detonator for coal mining has been manufactured through a two-phase granulation process. The new composite explosive (NCE) contains 79–88 wt% RDX, 3–5 wt% polymer binder, 1.5–2.5 wt% insensitive agent, 6–14 wt% sodium aluminum silicate (SAS), and 1–2 wt% polyvinyl alcohol (PVA). Firstly, a water suspension granulation method was utilized to produce spherical explosive molding powder. Then, the molding powder was coated with a flame inhibitor by a spraying granulation technique. Comparatively, the molding powder provided in this work outperforms the powder manufactured from other processing in terms of fluidity, particle size distribution, flame inhibitor coating quality, and accumulation of static electricity as a result of the chemical composition and the unique granulation process. This study offers a new type of detonating explosive with improved safety and initiating ability for mining industries, and it may also provide a novel strategy for processing other types of energetic materials.

Properties of dust clouds of novel hydrogen-containing alloys

Novel hydrogen-containing alloys based on aluminum, boron, and magnesium hydride (MgH2) are fabricated in a special process. The properties of their dust clouds (minimum ignition energy, minimum explosive concentration, and maximum explosion pressure) are studied. The results show that the minimum ignition energies of the novel hydrogen-containing alloys are 20–40 mJ, which is 50 mJ lower on the average than those of flake aluminum. The minimum explosive concentration values are between 20 and 30 g/m3. The maximum explosion pressure of the novel hydrogen-containing alloys is up to 0.88 MPa at the dust cloud concentration of 750 g/m3, which is obviously higher than that of flake aluminum (0.78 MPa). Magnesium hydride existing in the alloy can change the way of energy releasing and improve the efficiency.

A pressurized vessel test to measure the Minimum Burning Pressure of emulsion explosives

It is well known that emulsion explosives locally ignited in closed vessels do not undergo sustained combustion when the pressure is lower than some threshold value. The latter is usually referred to as the Minimum Burning Pressure (MBP) of the explosive and is now being used by some manufacturers as a basis of safety for many associated manufacture, transport, and handling processes. In the present work, both an apparatus based on hot-wire ignition and an associated methodology were developed to measure the MBP of emulsion explosives. Typical formulation of emulsion explosives in China was been measured. Water content, oil phase, emulsifiers and inorganic salts are all have important influence to MBP value. It is also shown that the MBP is a very important and useful safety parameter as, if an emulsion explosive formation pressure is maintained below its MBP, accidental ignition and propagation should not be possible.