Effect of Aluminum Particles

Effects of Aluminum Particles. Dependence on Particle Type (9)... 

We had an interest in knowing whether aluminum coatings would improve the survivability of the foams in space. Rather than preparing the foams in a skin of metal or other material, we evaluated intimately mixing aluminum particles into the foam mix. We could find no previous mention of studies of the effects of aluminum particles on mixing or on ultimate foam properties. Interestingly, with... 

Mock, W. and Drotar, J.T. (2007) Effect of aluminum particle size on the impact initiation of pressed PTFE/Al composite rods. Shock Compression of Condensed Matter-2007, pp. 971-974. 

Combustion of aluminum particle as fuel, and oxygen, air, or steam as oxidant provides an attractive propulsion strategy. In addition to hydrocarbon fuel combustion, research is focussed on determining the particle size and distribution and other relevant parameters for effectively combusting aluminum/oxygen and aluminum/steam in a laboratory-scale atmospheric dump combustor by John Foote at Engineering Research and Consulting, Inc. (Chapter 8). A Monte-Carlo numerical scheme was utilized to estimate the radiant heat loss rates from the combustion products, based on the measured radiation intensities and combustion temperatures. These results provide some of the basic information needed for realistic aluminum combustor development for underwater propulsion. 

Fig. 11.17 shows burning rate augmentation, Eb, as a function of the adiabatic flame temperatures of B-AP and Al-AP pyrolants. The incorporahon of aluminum particles into a base matrix composed of AP-CTPB pyrolant increases Ej. However, the effect of the addihon becomes saturated for adiabahc flame temperatures higher than about 2500 K. On the other hand, the incorporahon of boron particles into the same base matrix increases Eg more effectively, even though the adiabahc... 

The sonophotocatalytic system is effective for overall water splitting as shown in Fig. 12.2 and Table 12.1. This system requires, properly, a photocatalyst such as particulate Ti02. As ultrasonic waves pass through the solution, the properties of the solution influence a sonochemical reaction. In particular, negative effects are considered in the presence of powdered photocatalysts. The effects of fine particles in the solution on the sonochemical reaction have been noted so far. For example, Yasuda et al.19) reported the effects of insoluble particles, such as silicon oxide (Si02) or aluminum oxide (Al203), in the reactant solution on the sonochemical reaction and demonstrated that the reaction rate constant depended on particle properties, particle size and number of particles. It is assumed that a powdered photocatalyst suspended in the solution obstructs the transmission of ultrasonic waves. In this section, the influence of the photocatalyst powder suspended in solution on the sonochemical reaction is examined. 

An oxide coating forms on the surface of aluminum particles, which tends to protect it against chemical action. This oxide layer is also formed on magnalium, but is less protective. (In alloys of less than 30% aluminum, the oxide coating s effectiveness has been significantly reduced.) In terms of safety ... 

Another potential disadvantage arises from the lead content of the solder bump. Containing radioactive isotopes, most lead is a source of alpha particles that can potentially change the state of nearby transistors not shielded by aluminum. The effects of alpha particles are mainly of concern to dynamic random access memories (DRAMs) and dynamic logic. 

A bimodal distribution of polygonal aluminum nitride and planar boron nitride fillers was used for the examination of effects of the particle size and the relative composition in an attempt to enhance heat conduction of epoxy (Hong et al. 2012). The optimal thermal conductive path was strongly influenced by the packing efficiency and interfacial resistance of the particles in a sensitive way. Maximum thermal conductivity was achieved up to 8.0 W/mK in the 1 1 volume ratio of both types of particles. This methodology revealed that different particles should be packed closely to fill up the interstitial space and, simultaneously, the contact resistance and the contact area of the fillers should be balanced to maximum enhancement of the thermal conductivity. 

The higher efficiency of fortified rosin sizes is beHeved to result from the semihydrophilic nature of the rosin adduct molecules, which results in a more dispersed system of particles during size precipitation by alum. Consequendy, there is a more uniform distribution of somewhat smaller particles on the sized fibers. This dispersing effect may result from the strong tendency of aluminum to coordinate with organic anions. 

Sodium alumiaate is an effective precipitant for soluble phosphate ia sewage and is especially useful ia wastewater having low alkaliaity (20,21). Sodium alumiaate hydrolyzes ia water to Al(OH)2 and Al" which precipitate soluble phosphate as aluminum phosphate [7784-30-7], AlPO. Sodium alumiaate has also been described as an effective aid for the removal of fluorides from some iadustrial waste waters (22). Combiaations of sodium alumiaate and other chemicals are being used to improve the detackification of paint particles ia water from spray-painting operations (23). 

FIQURE A-6-1.2. Schematic effect of particle size and equivalence ratio on MIE of aluminum. 

Coulomb blockade effects have been observed in a tunnel diode architectme consisting of an aluminum electrode covered by a six-layer LB film of eicosanoic acid, a layer of 3.8-nm CdSe nanoparticles capped with hexanethiol, and a gold electrode [166]. The LB film serves as a tunneling barrier between aluminum and the conduction band of the CdSe particles. The conductance versus applied voltage showed an onset of current flow near 0.7 V. The curve shows some small peaks as the current first rises that were attributed to surface states. The data could be fit using a tunneling model integrated between the bottom of the conduction band of the particles and the Fermi level of the aluminum electrode. 

The effect of particle size, and hence dispersion, on the coloring properties of aluminum lake dyes has been studied through quantitative measurement of color in compressed formulations [47], It was found that reduction in the particle size for the input lake material resulted in an increase in color strength, and that particles of submicron size contributed greatly to the observed effects. Analysis of the formulations using the parameters of the 1931 CIE system could only lead to a qualitative estimation of the effects, but use of the 1976 CIEL m v system provided a superior evaluation of the trends. With the latter system, the effects of dispersion on hue, chroma, lightness, and total color differences were quantitatively related to human visual perception. 

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