Effect Of Inert Additives Research Articles

Numerical simulations of near-field blast effects using kinetic plates

Numerical simulations using two hydrocodes were compared to near-field measurements of blast impulse associated with ideal and non-ideal explosives to gain insight into testing results and predict untested configurations. The recently developed kinetic plate test was designed to measure blast impulse in the near-field by firing spherical charges in close range from steel plates and probing plate acceleration using laser velocimetry. Plate velocities for ideal, non-ideal and aluminized explosives tests were modeled using a three dimensional hydrocode. The effects of inert additives in the explosive formulation were modeled using a 1-D hydrocode with multiphase flow capability using Lagrangian particles. The relative effect of particle impact on the plate compared to the blast wave impulse is determined and modeling is compared to free field pressure results.

The Effect of Inert Additives on the Activation Period of Mechanically-Induced Self-Propagating Reactions

The Effect of Inert Additives on the Activation Period of Mechanically-Induced Self-Propagating Reactions

The Effect of Inert Additives on the Activation Period of Mechanically-Induced Self-Propagating Reactions

The Effect of Inert Additives on the Activation Period of Mechanically-Induced Self-Propagating Reactions

Self-Sustaining Metal-Sulfur Reactions Induced by Ball Milling

Combination reactions between chalcogen elements and metals are probably the most widely studied mechanically induced self-sustaining reactions (MSR). A series of five papers by Chakurov and his collaborators in the 1980s [1, 6–9] represents the first results on MSR. More recently, we performed detailed investigations on the Sn–Zn–S system [10, 12]. Those efforts resulted in hundreds of ignition time data, which exhibit systematic variation as a function of composition and milling conditions. It was shown that the degree of mechanical activation can be characterized by the mechanical dose received by the powder charge. Whether a reaction can become self-sustaining or not depends primarily on its thermodynamic properties, such as the adiabatic temperature. The ignition time, however, is more sensitive to the hardness of the reactants. The effect of inert additives is discussed, again contrasting thermodynamic and kinetic factors. The mutual suppression of ignition in mixtures of binary systems that show MSR by themselves is described.

Ignition of thermally thin thermoplastics — the effectiveness of inert additives in reducing flammability

We describe a mathematical model to evaluate the retardancy effect of inert additives on the flammability parameters of thermally thin thermoplastics in radiative ignition experiments. The concept of a critical mass flux from the solid phase into the flame is used as the criticality condition for defining ignition. Kinetic parameter values are chosen by relating the Arrhenius parameters to the ‘characteristic temperature’ measured in thermogravimetric experiments (TG). The specific application that we have in mind for our model is piloted ignition in the Cone Calorimeter.

Percolation phenomena in explosive mechanochemical synthesis of some metal chalcogenides

Percolation phenomena are observed during the transition from an explosive to nonexplosive mechanochemical synthesis in Met-Met-Halc systems. The transition occurs under the effect of inert additives. In the systems investigated the inert admixtures are unreacted metals and metal chalcogenides synthesized nonexplosively. Two explosive synthesis mechanochemical reactions and two critical volumes x c 1 and x c 2 for the transition from an explosive to a nonexplosive mechanochemical reaction, respectively, correspond to the Met-Met-Halc system. Depending on the x c 1 and x c 2 values, three possible cases, considered in the percolation theory, are observed. It is shown that the final product synthesized in a nonexplosive mechanochemical way plays the role of an inert impurity. On this basis, a mechanism is proposed which explains the existence of a series of mechanochemical, in principle, nonexplosive reactions.

The effect of inert additives on the explosive mechanochemical synthesis of some metal chalcogenides

The effect of different inert additives on the mechanochemical synthesis of SnS was studied. A transition from explosive to nonexplosive mechanochemical reaction was observed. It was shown that this change takes place only when a critical volume x c is occupied by inert material. The critical volume for a transition from an explosive to nonexplosive mechanochemical synthesis were determined for the chalcogenides of Zn, Cd, and Sn. The x c values obtained are discussed. On the basis of the new data concerning the critical dimensions r c of the exploding mechanical aggregates and the percolation phenomena, a mechanism for the transition from an explosive to nonexplosive mechanochemical synthesis is suggested.

Effects of inert additives on the divergence speed of plates driven by mixed explosives

Little is known about the effects of inert additives on the driving capacity of mixed explosives. This paper measures the effects of inert additives on the collision speeds between plates produced by explosive mixtures. The main result from the first series of experiments is that the divergent speed was reduced for the denser additives. The divergent speed is also independent of the dispersion of the additive in the range used for mixtures containing potassium chloride and aluminum. In the second series, the volume proportion of the additive was constant, while the mass proportion varied in accordance with the density. In conclusion, the reduced divergence speed for a metal plate displaced from the end of a charge containing an inert additive is largely determined by the density of the additive.

Free Convection Diffusion Flames With Inert Additives

An analysis of laminar, free-convection, diffusion flames burning on a vertical fuel surface is presented. The study is directed towards determining the effects of inert additives on the boundary layer structure and burning rates. Results are presented for several classes of inert additives using polymethyl methacrylate burning in air as the base system. The use of a fuel-phase additive to release noncombustible gases is modeled by varying the parameter YFT, the mass fraction of fuel in the gaseous products of pyrolysis. The effects of an additive which promotes char formation is modeled by varying the heat of pyrolysis per unit mass of gaseous pyrolysate released for combustion. The effects of a spray of water droplets on a wall fire is modeled by a combination of the release of a noncombustible gas and a surface heat sink which results from evaporation of water droplets at the fuel surface. The water spray calculations predict an extinction limit which is within a factor of two of experimental results.

Detonation of highly diluted porous explosives. I. Effect of inert additives on detonation parameters

Detonation of highly diluted porous explosives. I. Effect of inert additives on detonation parameters

Study of detonation wave structure

The detonation wave structures of hydrogen-oxygen detonations were studied experimentally and computationally. Experimental methods used in this study were high speed framing photography and soot pattern records. A two-dimensional cell model was proposed and the velocity change observed in a single cell was explained by the processes occurring in the cell. The three-dimensional detonation structure in a rectangular tube was determined and applied to one-mode detonation. It was concluded that the detonation proceeds in a complex surface of spherical and cylindrical waves that converge and diverge repeatedly. The effect of inert additives on the regularity of the cell structure was observed experimentally and the causes of irregular structure were studied from two points of view: First, to check whether the initial shock pressure and temperature lie inside or outside the second explosion limit. It was ascertained that polyatomic diluents generally give outside points in P-T diagrams. Second, to conduct a numerical analysis of one-dimensional shock waves followed by reactions. It was found that nitrogen dilution gave a long induction period followed by a sharp temperature and pressure rise. This should result in a pressure pulse that overtakes the shock front. These may be important factors for the disturbance of the cell structure.

Effect of inert additives on the detonation properties of igdanite

Effect of inert additives on the detonation properties of igdanite

Collisional Deactivation of Intermediate C4H8+ Ion in the Photolysis of Ethylene at 1048–1067 Å

The vacuum ultraviolet of photolysis of ethylene with argon resonance radiation leads to ion formation with a quantum yield (ionization efficiency) of 0.218 ± 0.015. Ethylene ion immediately forms an adduct with ethylene with an internal energy of 58 kcal/mole above the most stable 2-butene or methylpropene ion configurations. Neutralization of the C4H8+ ions by charge exchange with toluene, dimethylamine, or trimethylamine yields 2-butene and methylpropene as neutral counterparts to ions assumed to have a similar structure. The relative abundance of the isomers is dependent on the concentrations of charge acceptor and of inert gases. Results are interpreted in terms of an equilibrium between the ionic precursors of 2-butene and methylpropene. A transition state corresponding to a loose methylcylopropane ion structure, with a barrier of about 30 kcal/mole, is postulated for the isomerization. The effects of inert additives and ethylene, which does not react rapidly with C4H8+ ion, are ascribed to successive energy loss by collision and a resultant change in the equilibrium constant. This model is developed quantitatively and it is shown that, within the framework of some limiting assumptions, energy transfer in nonreactive ion–molecule collisions is considerably less than anticipated on the basis of an intimate complex. This is ascribed to inefficient energy loss for ion–molecule collisions at large impact parameters where redissociation occurs rapidly as a result of small increases in over-all angular momentum.