Aluminum Alloys In Water Research Articles

Entropy optimization in squeezed nanofluidic dissipative transport of radiative water conveying aluminum alloys

In this paper, squeezing transport of radiative water conveying aluminum alloys (i.e., AA7072 and AA7075) mobilized by entropy generation and dissipative energy is analyzed. Problem is formulated in a rotating frame with the consideration of magnetohydrodynamics and Joule heating aspects. Maxwell model for nanofluid has been used to incorporate the thermophysical properties of nanoelements. Formulated governing expressions have been transformed into system of ODEs by introducing similarity variables. The transformed system of ODEs is then numerically solved by Runge–Kutta–Fehlberg (RKF) method based on shooting background. The physical quantities (i.e., skin-friction coefficient, Nusselt and Bejan numbers) of scientific interest are formulated and illustrated via various plots. Graphical representations of squeezing function, temperature profile and velocity profile have been made to examine the effects of involved parameters. Streamlines and isotherms patterns have been formed and discussed. To authenticate the validity of model, skin-friction values have been compared with published literature for limited version of the model. Entropy and temperature of the system are improved with the involvement of aluminum alloys in water. Symmetrical behavior of streamlines is observed for positive approach of squeezing parameter.

Effects of Mg and Si Doping on Hydrogen Generation via Reduction of Aluminum Alloys in Water

Harnessing the oxidation–reduction reaction between aluminum and water is an attractive option for hydrogen generation and storage. Using liquid metals as a method of circumventing aluminum’s nativ...

Hydrogen production for micro-fuel-cell from activated Al–Sn–Zn–X (X: hydride or halide) mixture in water

A systematic investigation of hydrogen production from milled Al–Sn–Zn–X (X: hydride or halide) mixtures in pure water was performed at room temperature. The hydrolysis mechanism of the mixtures was based on the work of micro-galvanic cell between aluminum and tin in water where aluminum reacted with water to generate AlOOH (Boehmite) and hydrogen. It was found that many effects such as milling time, temperature, additives and mass ratio had a significant role in the hydrogen production rate, especially that of the additives (hydride or halide) led to reduction of crystallite size and accumulation of uniform mixing. They also produced a lot of heat and the conductive ions which simulated the work of micro-galvanic cell. The milled Al–Sn–Zn–X (X: hydride or halide) mixtures had high reactivity and Al–Sn–Zn–MgH 2 mixture produced 790 mL g −1 hydrogen in 5 min of the hydrolysis reaction with the activation energy of 17.570 kJ mol −1, corresponding to 7.04 wt.% hydrogen excluding water mass. Therefore, a new method of CO 2 free and safe hydrogen production for micro-fuel-cell was obtained from the activated aluminum alloys in water.

Experiment assessment of hydrogen production from activated aluminum alloys in portable generator for fuel cell applications

Abstract An experiment assessment of hydrogen production from activated aluminum alloy in portable hydrogen generator for fuel cell applications was investigated. The optimum hydrogen capacity of the high–reactive Al–Bi–NaCl alloys (the abbreviation of milled material of aluminum, bismuth and NaCl particles) is about 9–9.4 wt.%, meeting the targets (9 wt.%) of the US Department of Energy in 2015. Hydrogen production rate can be controlled via controlling the water flow rate in the generator, being 1.369–6.198 L hydrogen/min while the water flow rate ranges in 5–20 mL/min. The larger water flow rate often leads to higher temperature and results in unsafety in the generator as the hydrolysis reaction of aluminum alloy and water releases 15 kJ/g heat. However, the heat problem can be successfully eliminated by using effective cooling stytles, which enable the maximum temperature of Al–H2O mixture (the abbreviation of hydrolysis products of aluminum alloy in water) controlled less than 474 K even though the water flow rate is 20 mL/min. Therefore, the experiment results show that the portable hydrogen generator from aluminum alloy could supply the CO2–free, high hydrogen capacity and safe hydrogen for fuel cell applications.

ESR and DRES study of the state of cobalt, nickel, and copper in oxide catalysts obtained from activated aluminum alloys

ESR and DRES were used to study the state of the cobalt, nickel, and copper ions in catalysts obtained by dissolving cobalt-, nickel-, and/or copper-containing activated aluminum alloys in water with subsequent roasting or impregnation of the support obtained by dissolving activated aluminum in water and solutions of Co, Ni, or Cu nitrates. The formation of highly dispersed M0 aggregates, which are rather readily oxidized, is characteristic before heat treatment for Co-and Ni-containing catalysts obtained from the alloys. In the case of Cu-containing systems, several types of copper ions are observed independently of the method of synthesis even before heat treatment. Heat treatment leads to the aggregation of oxidized Co2+ ions to give highly dispersed oxide phases. The roasted nickel and copper catalysts contain several types of nickel and copper ions, respectively.

State of the copper ions in the catalysts for oxidation of carbon monoxide to carbon dioxide

The state of the copper ions in the catalysts for the oxidation of carbon monoxide to carbon dioxide, prepared by dissolving an activated copper-containing aluminum alloy in water followed by calcination (method A) and by impregnation of the support produced by dissolving activated aluminum in water with copper nitrate solution (method B), was investigated by diffuse reflection electronic spectroscopy. It was established that the catalysts contain Cu2+ ions stabilized in fields of octahedral symmetry. The concentration of these ions depends on the method of synthesis of the catalyst, its copper content, and the pretreatment temperature. It is higher in the samples produced by impregnation than in the samples produced by fusion; increase in the amount of copper leads to a decrease while increase in the calcination temperature leads to an increase in the concentration of the above-mentioned ions. Treatment of the oxide systems with the reaction mixture does not affect the state and concentration of Cu2+. The catalytic activity of the samples depends on the method of preparation and increases with decrease in the amount of Cu2+ (Oh) and with increase in the content of the CuO phase in the system.

Polarization Studies of Aluminum Alloys In Water at 200 C and 300 C

Abstract Specimens of commercial 2S aluminum and two special alloys containing iron and nickel were polarized anodically and cathodically at a number of different current densities at 200 C and 300 C. Weight gains were obtained and the potentials relative to the stainless steel autoclave were measured by an interrupter method. The weight gain data indicated that the polarizing current is being carried by electronic conduction. The potential-time curves for anodic polarization indicate differences between 2S aluminum and the alloys in that greater polarization is obtained with the latter. These curves also indicate that the impressed current decreases the film resistance. In all cases the potential reached a plateau value with time and this time was shorter for the alloys. The potential-time curves for cathodic polarization also show plateau values but the rise to a plateau value is in the opposite sense to the applied current. With increasing cathodic polarization the plateau values occur at more negative values of the potential. This latter trend is in the same direction as the applied polarizing current. This apparently is explained in terms of the build-up of the aluminum oxidation potential which acts in a sense opposite to the applied current. Again the time to reach plateau values was shorter for the alloys. Voltage current curves were also obtained on specimens left overnight (approximately 17 hours) at two different anodic polarizing currents. These curves indicated differences between 2S aluminum and the alloys; these differences are discussed in terms of the semi-conducting properties of the oxide film. The observations made on the differences in the properties of the oxide films on the materials examined as revealed by potential and polarization curves are discussed as to their significance in determining corrosion resistance.

Polarisation of nickel and aluminium in neutral solutions

AbstractThe cathodic polarisation of nickel, aluminium, nickel‐aluminium alloy (2% nickel) and aluminium nickel‐plated with AI/Ni–1:1 and 10:1 under conditions of hydrogen evolution was studied at various temperatures in 3.17% IiCl solution. The results indicate a decrease in polarisation on alloying or plating with nickel, a decrease in polarisation with increasing temperature for nickel and an increase for aluminium under the same conditions. The results are discussed in terms of their effects on the corrosion resistance of aluminium alloys in water at elevated temperatures.

Structural Features of Corrosion Of Aluminum Alloys in Water at 300 C

Abstract A number of aluminum alloy specimens were immersed in distilled water heated to 300 C and a study made of the structural features of corrosion. Samples were of the following general types: Al-Ni alloys, Al-Fe alloys, Al-Ni-Fe alloys, Al-Cu alloys and Al-Ni-Si alloys. After exposure samples were examined by means of a metallographic microscope. In a number of cases the specimens were ground on a metallographic polishing wheel to reveal structural details of the corrosion process. Photomicrographs of both polished and unpolished specimens are included with the paper. 6.4.2

Aqueous Corrosion of Aluminum (Part 2-Methods of Protection Above 200 C)

Abstract At elevated temperatures most aluminum alloys in water suffer severe penetrating attack, resulting in their relatively rapid destruction. This penetrating attack is explained in terms of mechanical damage as a result of diffusion of corrosion-product hydrogen into the metal. It is prevented by adding to the water cations which are reduced on the aluminum to form deposits of low hydrogen overvoltage metals. It is also prevented in untreated water by using aluminum alloyed with the same metals. Alloying metals observed to be beneficial are nickel, copper, cobalt, iron and platinum, with nickel probably the most effective. There has been developed an alloy, containing approximately 1 percent nickel in 1100 aluminum,which appears to be completely safe against the penetrating attack up to 350 C. It is easy to make and is workable. It probably can be used, from a corrosion resistant point of view, wherever its normal reaction rate with water or a solution is tolerable. Penetration rates in static distilled water range from approximately 0.5 mg/dm2-day at 150 C to 18 mdd at 350 C (0.3 to 9 mils per year). They are higher where there is significant flow velocity of water past metal. 6.4.2