Particle Size Of Aluminum Powder Research Articles

Numerical simulation on the bomb case effects of non‐ideal aluminized explosive

AbstractThe detonation process of non‐ideal explosives is influenced by the casing of the bomb. Non‐ideal charges in the process of the explosion of live ammunition energy output mechanism and distribution ratio, the impact of the case on the explosion flow field, and other issues cannot be obtained through the existing theoretical analysis and testing techniques to obtain specific values. This paper establishes a “detonation+afterburning” energy output model to characterize the energy release characteristics of non‐ideal charges, using step‐by‐step numerical simulation of the near and middle, and far fields of the explosion, and verify simulation results through experiments, quantitative analysis the case of a type of earth penetrator on the normal particle size (4 μm) and two times the normal particle size (8 μm) of non‐ideal charges of aluminum powder explosion process. The results indicate that the presence of the casing enhances the energy output of aluminum powder with 4 μm by ≈5 %. When the particle size of aluminum powder is doubled, the maximum reaction rate and the peak of the shock wave are merely around 35 % and 75 %, respectively, compared to those of normal particle size. The detonation products, case fragments, and air constitute 49 %, 48 %, and 3 % of the overall explosion energy, respectively. The proportional equation of the conversion between the chemical energy of the explosion and the kinetic energy of the case fragments is obtained. These conclusions can provide data support for the design of non‐ideal charge warheads, lethality assessment, and establishment of engineering protection standards.

Preparation and characterization of anode foil for aluminum electrolytic capacitors by powder additive manufacturing

In this paper, anode foils for aluminum electrolytic capacitors were successfully prepared using additive manufacturing technology. The effects of sintering temperature and particle size the anode foil were investigated. The results indicated that the sintering neck and particle size were the key factors to determine the electrical properties of the prepared powder foil. As the sintering temperature increased, both the porosity and the pore diameter of the anode foil decreased and the sintering neck increased, resulting in a decline of specific capacitance, while the dissipation factor did not change significantly. As the particle size of aluminum powder increased, the porosity, the pore diameter and the sintering neck of the anode foil increased. The specific capacitance of the anode foil first increased and then decreased, while the dissipation factor showed a gradual decrease. The anodic foil sintered at 630 °C and prepared with aluminum powder of 5– 6 μm had the best electrical performance.

Experimental investigation of the catalyst-free reaction characteristics of micron aluminum powder with water at low and medium temperatures

Aluminum metal has a high energy density and can react with water to produce hydrogen instantly, which is environmental-friendly and safe. Aluminum has great potential to provide a good carrier for energy and hydrogen storage. The utilization of aluminum is constrained by the oxide layer on its surface. In order to promote the aluminum-water reaction to continue efficiently, the reaction needs to be activated. The modification of aluminum is often complicated and dangerous, and it is difficult to apply the hydrogen produced by the reaction and the heat released. The increase of temperature and pressure of the reaction has also been proved as a useful activation method. Continuous reactions are difficult to achieve at high temperature and pressure, and it becomes difficult to obtain reaction initiation and development processes. However, the reaction process has an essential impact on the utilization of the aluminum-water reaction. In this paper, the aluminum-water reaction process at medium temperature was investigated using micron aluminum powder. The effects of initial temperature, particle size of aluminum powder and water type on the reaction were further analyzed. In addition, the kinetic analysis of the aluminum-water reaction was carried out to obtain kinetic models. Experimental results indicate that the product of the aluminum-water reaction is Al(OH)3 at 90–150 °C. The reaction initial temperature shows a multipolar effect on the reaction between aluminum and water. The hydrogen yield from the reaction between ∼25 μm aluminum powder and tap water at 150 °C is 31.9 %. The pre-exponential factor and apparent activation energy increase with the reaction proceeding. The present research is conducive to further safe and efficient utilization of micron aluminum powder for energy conversion, and benefits the achievement of carbon peaking and carbon neutrality.

The Effect of Aluminum Particle Size on the Formation of Reactive Jet

In order to study the morphology characteristics of the PTFE/Al reactive shaped charge jet and the chemical reaction during the jet formation, PTFE/Al reactive liners with aluminum particle sizes of 5 μm and 100 μm were prepared. The parameters of the Johnson–Cook constitutive model of PTFE/Al reactive materials (RMs) were obtained through quasi-static compression experiments and SHPB (Split Hopkinson Pressure Bar) experiments. X-ray imaging technology was used to photograph the shape of reactive shaped charges jet at two different time points. The AUTODYN secondary development technology was used to simulate the jet formation, and the simulation results are compared with the experimental results. The results show that the simulation results are close to the experimental results, and the error is in the range of 4–8%. Through analysis, it is observed that the RMs reacted during the PTFE/Al reactive shaped charge jet formation, and due to the convergence of the inner layer of the liner during the jet formation, the chemical reaction of the jet is from inside to outside. Secondly, the particle size of aluminum powder has an influence on the chemical reaction and morphology of the jet. During the jet formation, there were fewer RMs reacted when the PTFE/Al reactive liners were prepared with 100 μm aluminum powder. Compared with 5 μm aluminum powder, when the aluminum powder is 100 μm, the morphology of the jet is more condensed, which is conducive to generating greater penetration depth.

Influence of micron-sized aluminum particles on micro-explosion and combustion characteristics of ethanol-biodiesel droplets under co-heat flow

• The characteristics of droplets doped with micron-sized particles were studied. • Increasing the particle size will promote the micro-explosion phenomenon. • The droplet heating time will vary due to changes in particle content. • The particle content of the optimal micro-explosion intensity is about 20%. As a high-energy metal fuel, aluminum powder particles (AP) have long been used as fuel propellants and combustion-supporting additives in explosives to meet the design requirements of a new generation of high-energy–density fuels. In this experiment, the micro-explosion and combustion characteristics of ethanol-biodiesel mixed droplets with different aluminum powder particle contents and particle sizes were studied under high temperature and pure oxygen environment. In order to better control the experimental variables, a more accurate single-droplet suspension method was adopted in this experiment. The entire evaporation and combustion process of the mixed fuel was completely recorded and analyzed by using high-speed photography technology, binarization imaging technology and droplet optimization algorithms. The experimental results show that when the content of aluminum powder particles remains unchanged, increasing the particle size of aluminum powder in the mixed droplets will promote the micro-explosion phenomenon. When the particle size of the aluminum powder contained in the mixed fuel is different, the increase of the particle content will have a completely different effect on the heating time of the droplet. When the particle size of aluminum powder particles is small, the combustion duration of the mixed droplets increases with the increase of aluminum powder content, while the opposite results are shown when the aluminum powder particles are larger. Increasing the amount of aluminum powder also extends the full life of the droplets. In addition, this study introduces the microburst intensity (MI), which provides a new idea and method for laterally comparing the microburst phenomena of fuel droplets with different initial diameters. For mixed fuel containing micron-sized aluminum particles, the particle content that produces the best micro-explosion intensity is about 20%.

Synthesizing AlN Coatings Using Suspension Plasma Spraying: Effect of Promotional Additives and Aluminum Powder Particle Size

Synthesizing AlN Coatings Using Suspension Plasma Spraying: Effect of Promotional Additives and Aluminum Powder Particle Size

Research on law and mechanism of dust explosion in bag type dust collector

The bag type dust collector will accumulate dust during long-term operation, and the high temperature during operation will cause dust explosion. In this paper, with the dust removal system involved in the “8·2” Kunshan dust explosion accident taken as the research background, the minimum ignition temperature and lower explosion limit experiments are carried out on aluminum powder with different particle sizes (10–60 μm) by using the lowest ignition temperature test device and the 20 L near-spherical explosive device. The dust concentration distribution and temperature field in the bag type dust collector are analyzed through the CFD-FLUENT software. Through the analysis of the experimental results, it is found that when the particle size of aluminum powder is 19 μm, the minimum ignition temperature is 585 °C, and the lower explosion limit of concentration is 0.04 kg/m3. The simulation results indicate that the dust particles gather in the dust collecting bucket, and the aluminothermic reaction occurs in the dust collecting bucket. The temperature of the upper and right parts in the dust collecting bucket is above 600 °C, which exceeds the minimum ignition temperature. At the interface between the dust hopper and the dust collecting bucket, the concentration of aluminum powder reaches 0.126 kg/m3, which exceeds the lower explosion limit of aluminum powder.

Effects of particle size of aluminum powder in silver/aluminum paste on n-type solar cells

Silver paste, which mainly consists of silver metal, glass frit, and organics, has been used for contacting n + emitter of conventional p-type solar cells, whereas aluminum-added silver paste (silver/aluminum paste) has been used for p + emitter of n-type solar cells. It has been reported that the addition of aluminum powder to the silver paste decreases contact resistance between the paste electrodes and the p + emitter with increasing content of the aluminum powder in the paste, and in addition, that the silver/aluminum paste creates large and deep metallic spikes underneath the paste, which has been considered to decrease the contact resistance. However, how particle size of the aluminum powder affects the contact resistance and the electrical characteristics of the n-type solar cells has not been clear yet. In this study, the effects of the particle size of aluminum powder in the silver/aluminum paste on the contact resistance and the electrical characteristics are investigated. Our study demonstrates that the particle size of the aluminum powder strongly affects the contact resistance and the electrical characteristics. The contact resistance decreases not only with increasing the content of the aluminum powder in the silver/aluminum paste, but also with increasing the particle size of the powder. In addition, the optimization of the particle size of the aluminum powder can effectively increase FF of the n-type solar cells, resulting in increasing efficiency of the cells.

Influence of aluminum particle size on ignition and nonstationary combustion of heterogeneous condensed systems

The results of studies of the effect of particle size of aluminum powder in condensed systems on the ignition, nonstationary combustion, and acoustic conductivity of the burning surface are presented. Analysis of the experimental data shows that the ignition delay and the temperature of burning surface of the heterogeneous condensed systems under study decrease with increasing particle size of aluminum powder, and the nature of the dependence of the nonstationary burning rate on the time of depressurization of the combustion chamber for compositions containing micron or ultrafine aluminum powders is in qualitative agreement with the phenomenological theory of nonstationary combustion. Replacement of micron aluminum powder by ultrafine powder in a heterogeneous condensed system increases acoustic conductivity.

Effect of catalytic additives and aluminum particle size on the combustion of mixed compositions with a chlorine-free oxidizer

Experimental results on the stationary burning rate and solid content in the combustion products of mixed compositions with a chlorine-free oxidizer and an active fuel binder in the pressure range 0.025–6.0 MPa are presented. The effect of catalytic additives (silica and carbon black), the particle size of aluminum powder, and the method of preparing samples for combustion of the mixed compositions under consideration are analyzed.

Influence of Parameters on Alumina Particles Size and Morphology

The sol - gel method is the effective technique to prepare high purity ultrafine alumina powder. Laser particle size analyzer and scanning electron microscopy were used to study the inflence of pH, leaching of precursor sol, surface modification of alumina powder on the secondary particle size. The impact of leaching sol on powder crystal was tested with X-ray diffraction. The results show that: aluminum nitrate solution showed different appearance with different pH values during titration aluminum nitrate solution with ammonia. When pH=3~5.5, the solution occur through no precipitation to the white precipitate, then the solution becomes relatively thin paste; when the pH was from 6.0 to 6.5, the solution becomes more thick paste. When the pH increased from 7.0 to 8.0, the solution has turned into a more dilute paste. The impact of pH on the particle size is: When the pH increased from 5.5 to 7.0, aluminum powder particle size gradually become thicker and larger. When the pH continues to rise, powder particle size is reduced, when the sol pH value is 8.0, it can get the smallest particle size for alumina powder, up to 548nm. Powder average particle size when adding TEA surfactant to sol is less than the sol without any surfactant particle size from the micrograph. Moreover, particle size is more uniform with TEA surfactant, but powder particle size which did not add surfactant to the sol is clear size differences and the dispersion is poor. When the sol containing surfactant, the effect of surface modification is not obvious. In the case of sol without surfactant powder particle size reduced after the surface modification, then powder surface modification is necessary, it can prevent the powder from congregating. The crystal type is relatively perfect and single α-Al2O3 after filtration, the crystal type without leaching is α-Al2O3 and γ-Al2O3, with a smaller particle size, crystal grain size is relatively smaller. If alumina sol isn’t be leached it contains ammonium nitrate, ammonium nitrate will decompose and release various gases during sintering, the gas emission has an crushed effect on the sintered powder.

Experimental study of the acoustic admittance of the burning surface of composite solid propellants

A method for measuring the acoustic admittance of the burning surface of solid propellants using a two-dimensional combustion chamber (T-burner) is considered. The paper presents the results of an experimental study of the effect of the pressure and frequency of acoustic oscillations in the combustion chamber and the effects of the composition, mass content, and aluminum powder particle size on the acoustic admittance of the burning surface of composite solid propellants.

Optimization and kinetics of the cementation of lead with aluminum powder

The cementation of lead with aluminum powder from the brine-leaching filtrate of lead-bearing zinc plant residues (ZPRs) has been investigated. The influence of several parameters on the course of the reaction such as aluminum powder quantity, time, aluminum powder particle size and temperature was examined. The optimum cementation conditions were found to be as aluminum powder quantity = 1.5 times of stoichiometric value, time = 90 min, aluminum powder fraction with a particle size − 125 + 88 µm and temperature = 70 °C. Cementation of lead was shown to be a feasible process to achieve a high degree of lead removal (~ 95%) within a fairly reasonable contact time. Also, the kinetics of the cementation was studied over a range of experimental parameters. The cementation was shown to be a diffusion-controlled reaction in the range of 50–70 °C with activation energy of 23.6 kJ/mol. However, the process was found to be highly temperature sensitive in the range 40–50 °C, suggesting a chemical reaction control model for that range. This finding was in concordance with a severe slope change in Arrhenius curve in the range 40–50 °C.

Thermal behavior of aluminum powder and potassium perchlorate mixtures by DTA and TG

In this work the thermal decomposition characteristics of micron sized aluminum powder + potassium perchlorate pyrotechnic systems were studied with thermal analytical techniques. The results show that the reactivity of aluminum powder in air increases as the particle size decreases. Pure aluminum with 5 μm particle size has a fusion temperature about 647 °C, but this temperature for 18 μm powder is 660 °C. Pure potassium perchlorate has an endothermic peak at 300 °C corresponding to a rhombic–cubic transition, a fusion temperature around 590 °C and decomposes at 592 °C. DTA curves for Al 5/KClO 4 (30:70) mixture show a maximum peak temperature for thermal decomposition at 400 °C. Increasing the particle size of aluminum powder increases the ignition temperature of the mixture. The oxidation temperature increased by enhance in the aluminum content of the mixture.

Formulation effects on the burning rate of aluminized solid propellants

Porous ammonium perchlorate was prepared by a fluidization process at 230°C, the product of which was used as a partial substitute for crystalline ammonium perchlorate in composite solid propellants. Fourteen aluminized propellants were divided into five groups containing various promoters (modifiers) having different burning rates in order to compare the effects of aluminum powder particle size on the burning rates of the propellants. Aluminum powders having three particle sizes (6-9,16-19, and 60 /im) were used. The burning rate was measured in a strand burner at 30, 50, 70, 100, and 150 atm of nitrogen pressure. The burning rates of propellants containing catocene or n-butylferrocene as a promoter increased with decreasing aluminum particle size. When copper chromite and/or ferric oxide was used as a promoter, the particle size of aluminum had no effect on the burning rate of the propellant. Therefore, the effect of aluminum particle size on the burning rate depends on the burning rate modifier in the propellant.

Volume changes experienced by Al-Zn compacts during liquid-phase sintering

The sintering of compacts from aluminum powders with zinc additions in the presence of a liquid phase is accompanied by their volume growth and a corresponding increase in their porosity. The volume growth of compacts from Al-Zn powder mixtures during liquid-phase sintering is mainly due to the Kirkendall effect, which manifests itself during the formation of a solid solution on the aluminum particles as a result of the diffusion of zinc atoms from the melt to the particles preceding their dissolution in the liquid phase. In general, the porosity of sintered compacts is satisfactorily described by Eq. (1). When, however, the zinc content of a compact does not exceed its limit of solid-phase solubility in aluminum at the sintering temperature, the process of dissolution of aluminum in the melt may be ignored. In such a case the end porosity of compacts is described by Eq. (2) with a correction for shrinkage due to a regrouping of particles. The extent to which the volume of compacts from an Al-Zn powder mixture grows during sintering increases with increasing mean aluminum powder particle size.

窒素ガスふん囲気中で作製したアルミニウム焼結体とその陽極酸化についての研究

In this study, an anodic oxidation was made by electrolysis by using a sintered body of aluminum prepared in nitrogen atmosphere as anode and ammonium dihydrogen phosphate as electrolyte A dielectric element thus obtained was made into a solid electrolytic condenser by coating with manganese dioxide (MnO2) as semiconductor. That is: a solid electrolytic condenser of sintered sluminum was prepared. Experiments were conducted to examine the effects of particle size of aluminum powder and compacting pressure on electric characteristics of the condenser. The particle size in the experiments was of 4 kinds: 20, 35-150, 150-200, and 200 mesh, and the compacting pressure applied was 0.1 and 0.2t. The capacitance at 120Hz was assumed to be 100 as a standard and the ratio of capacitance at each frequency was considered for examination. As the results of experiments, it was observed that the capacitance ratio at each frequency was smaller and the value of tan δ was larger with the decrease in particle size of aluminum powder, and there were little differences between the effects of 0.1 and 0.2t of compacting pressure.

The effect of the particle size of aluminum powder on the sintering of a Cu-Al alloy in the presence of a liquid phase

1. During the sintering of mixed copper and aluminum powders at temperatures above the eutectic point, the compacts exhibit growth, which depends on the particle size of the aluminum powder and the rate of heating during sintering. 2. The smaller the aluminum particle size of an alloy and the slower the heating of specimens to the temperature of isothermal holding, the greater is the extent of volume growth in the presence of a liquid phase. 3. The observed growth is attributed to the preferential diffusion of the aluminum atoms from the liquid into the solid phase. When the diffusion cannot proceed to a sufficient extent, the compacts may exhibit shrinkage.