Mn+Sb2O3Thermite/Intermetallic Delay Compositions (original) (raw)
Related papers
Tungsten and Copper (II) Oxide Mixtures as Gasless Time Delay Compositions for Mining Detonators
Materials
The widespread use of pyrotechnic compositions in time delay detonators is the reason for research aimed at expanding knowledge of the combustion properties of new pyrotechnic mixtures, whose components react with each other in the solid or liquid state. Such a method of combustion would make the rate of combustion independent of the pressure inside the detonator. This paper presents the effect of the parameters of W/CuO mixtures on their properties of combustion. As this composition has not been the subject of previous research and is not described in the literature, the basic parameters, such as the burning rate and the heat of combustion, were determined. In order to determine the reaction mechanism, a thermal analysis was performed, and the combustion products were determined using the XRD technique. Depending on the quantitative composition and density of the mixture, the burning rates were between 4.1–6.0 mm/s and the heat of combustion in the range of 475–835 J/g was measured...
Some Aspects of the Burning Process of Antimony and Potassium Manganate(VII) Compositions
Materials
Antimony and potassium manganate(VII) compositions are widely used in time delay elements of detonators. Despite the existing literature on such systems, there is no complete information on the burning process of Sb/KMnO4 compositions in closed systems. There are also no data on the heat of their combustion in conditions of increased pressure without the access of oxygen from the air and on the composition of solid combustion products. These issues are the subject of the presented work.
Defence Technology, 2018
Significance of body material and temperature variation on burning time and burning rate of Si/PbO/ Pb 3 O 4 /FG and B/BaCrO 4 /FG pyrotechnic delay compositions were experimentally studied. Brass and stainless steel were used as delay body materials. High resolution oscilloscope and a customized chronometer were simultaneously used for the measurement of burning time and burning rate. Results reveal that brass material with controlled column dimensions reduced the variation in burning time of Si/PbO/ Pb 3 O 4 /FG delay mixture from 7.43% to 4.17% and that of B/BaCrO 4 /FG mixture from 16.83% to 9.39%. Similarly the variation in burning rate was reduced from 7.57% to 4.12% and from 17% to 9.69% for Si/PbO/ Pb 3 O 4 /FG and B/BaCrO 4 /FG mixtures respectively. Si/PbO/Pb 3 O 4 /FG delay mixture was also subjected to temperature ranging from À54 C up to þ100 C. The burning rate of this composition varied linearly with temperature. Burning rate increased from 28.01 mm/s to 34.38 mm/s when the temperature was varied from À54 C to þ100 C.
Journal of Thermal Analysis and Calorimetry, 2018
The effect of mass ratio of fuel to oxidant in pyrotechnic compositions of Mg/Ba(NO 3) 2 and Mg/Sr(NO 3) 2 was studied using the non-isothermal thermogravimetry (TG) and differential scanning calorimetry (DSC) techniques. The mass ratios 10:90, 25:75 and 50:50 of Mg powder to oxidant (nitrate salt) were used for preparation of pyrotechnic compositions. The kinetic parameters of thermal ignition reactions of pyrotechnics were obtained by using TG/DSC curves under nitrogen atmosphere at heating rates of 20, 25 and 30°C min-1. The DSC curves showed that the 25:75 weight ratio of fuel to oxidant resulted in a complete ignition reaction and showed the highest enthalpy of the reaction. Also, this mass ratio was not indicated a mass gain after the combustion step in the TG curves. The model-free methods of Kissinger, Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) were used for calculation of activation energy (E a) of ignition reactions of pyrotechnics. The E a values 130.5 and 146.3 by Kissinger, 138.3 and 153.2 by OFW and 132.2 ± 2.4 and 146.3 ± 1.7 kJ mol-1 by KAS methods, respectively, were obtained for Mg/Ba(NO 3) 2 and Mg/Sr(NO 3) 2 pyrotechnics. Also, the nonlinear model-fitting method was used to determine the pre-exponential factor (A) and kinetic model function. The sigmoidal shapes were resulted from the curves of conversion factor (a) versus T. The model of A 3/2 with the functions of g(a) = [-ln(1-a)] 2/3 and f(a) = 3/2(1-a)[ln(1-a)] 1/3 as a nucleation reaction model was proved by using the model-fitting method for the ignition reaction of both pyrotechnic compositions. The ln A values 8.1 and 7.6 min-1 were obtained, respectively, for the ignition reaction of magnesium powder with Ba(NO 3) 2 and Sr(NO 3) 2 .
Review of Gasless Pyrotechnic Time Delays
Propellants, Explosives, Pyrotechnics, 2018
Gasless pyrotechnic delay compositions for time‐sequencing energetic events are reviewed. They are mixtures of powdered fuels and oxidants capable of a highly exothermic oxidation‐reduction reaction. Trends favor ‘green’ compositions targeted to replace compositions containing perchlorates, chromates, lead and barium. Thermite‐based reactions dominate but intermetallics (especially multi‐layered versions) and hybrids appear promising considering progress in self‐propagating high temperature synthesis technology. Improving computer modelling will require better description of condensed phase reactions. Progress was made with the development of “hot spot” models and expressing reactivity in terms of the number of contact points (or contact surface area) between particles. Promising processing advances include mechanochemical synthesis of reactive particle composites by arrested milling or comminution of cold‐rolled multilayer intermetallics. Dry mixing of reactive powders has made way...
Journal of Energetic Materials, 2018
An experimental investigation was carried out to determine the effect of binders and loading pressures on burning performance of B/BaCrO 4 and Si/ PbO/Pb 3 O 4 delay compositions. The consolidated density and percent theoretical maximum density (%TMD) of these compositions were also studied with different binders and at multiple loading pressures. Carboxyl methyl cellulose (CMC), dextrin, and fish glue with varying wt. % were used as binders. It was observed that the burning rate of these delay compositions was inversely proportional to the binder content. The burning rate of B/ BaCrO 4 delay composition was 71.0 mm/s without binder. The burning rate decreased to 38.1 mm/s by adding 3.0 % fish glue. When 1.0 % CMC was added to the mixture, the burning rate decreased to 61.8 mm/s. By adding 3.0 % dextrin to the delay composition, the burning rate decreased to 38.2 mm/s. The burning rate of Si/PbO/Pb 3 O 4 delay mixture was 38.6 mm/s without binder. The burning of this mixture decreased to 16.4 mm/s by adding 1.0 % fish glue. The loading pressures were varied from 103 to 414 MPa. The effect of loading pressures on the burning rate of both the delay compositions was marginal. The burning rate of B/BaCrO 4 delay mixture decreased with the increase in loading pressure. On contrary, the change in burning rate of Si/PbO/Pb 3 O 4 pyrotechnic delay composition was minimal by varying the loading pressures. Results also revealed that loading pressures of 345 and 348 MPa produced the minimum standard deviation in burning rate of B/BaCrO 4 and Si/PbO/Pb 3 O 4 compositions. The consolidated density and %TMD of both mixtures increased by adding binders and increasing the loading pressures.
Engineering, Technology & Applied Science Research, 2017
In the present study, experimental investigation was carried out on the delay time consistency of modified Si/PbO/Pb3O4/FG pyrotechnic delay composition in a delay tube. Where Si is the fuel, PbO/Pb3O4 are oxidizers and Fish Glue (FG) is the binder. Ingredient mixing and loading pressure were studied. Results revealed that homogenous mixing of the delay composition is a very critical parameter for controlling the time consistency of pyrotechnic delay composition. The delay time accuracy was improved from 25% to about 7.42% by ensuring homogenous mixing of the ingredients. Results also show that loading pressure ranged from 30,000 to 65,000 psi did not affect much the delay time of this pyrotechnic composition and the burning rate.
Performance and Aging of Mn/MnO 2 as an Environmentally Friendly Energetic Time Delay Composition
ACS Sustainable Chemistry & Engineering, 2014
The Mn/MnO 2 reactive system was investigated as a suitable replacement for the traditional W/BaCrO 4 /KClO 4 /diatomaceous earth delay composition. The delay performance, ignition sensitivity, and aging characteristics were examined in aluminum microchannels similar in diameter to common delay housings (4.7 mm). Stoichiometries with measured combustion temperatures between 1358 and 2113 K were self-sustaining with combustion velocities ranging from 2.4 to 7.3 mm s −1 . The Mn/MnO 2 system produced less gas than W/BaCrO 4 /KClO 4 /diatomaceous earth compositions allowing consideration for use in sealed delay housings. Accelerated aging at 70°C and 30% relative humidity for 8 weeks resulted in no measurable loss of performance. Safety characterization showed that this composition is not sensitive to ignition by friction or electrostatic stimuli. The combustion products (as determined by X-ray diffraction) appear to be benign based on current regulations. Therefore, the Mn/MnO 2 system appears to be a suitable low gas-producing, nonsensitive, less toxic delay composition with good longevity.