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The main goal of the present study is to investigate the friction and wear behaviors of aluminum matrix composites with an A360 matrix reinforced with SiC, B₄C and SiC/B₄C particles.

Un‐reinforced aluminum casting alloy, Al/SiC, Al/B₄C and Al/SiC/B₄C aluminum composites were prepared for the present study. Friction and wear tests of aluminum and its composites versus AISI316L stainless steel were carried out for dry sliding condition using by a pin‐on‐disc arrangement. Tests were realized at the sliding speed of 0.5, 1.0 and 1.5 ms⁻¹ and under the loads of 10, 20 and 30 N. The microstructures of the present composites were examined by scanning electron microscopy and energy dispersive spectroscopy analysis.

The coefficient of friction of the composites is approximately 25‐30 percent lower than that of the un‐reinforced aluminum. The specific wear rate of the aluminum and its composites decreases with the increase in load and increases with the increment of sliding speed. Un‐reinforced aluminum has specific wear rate value of 1.73×10⁻¹³ which is the highest specific wear rate, while Al+17%SiC has specific wear rate value of 2.25×10⁻¹³ m² N⁻¹ which is the lowest specific wear rate among the tested materials. The average specific wear rates for Al+17%B₄C, Al+17%SiC/B₄C and Al+17%SiC composites are obtained about 49, 79 and 160 percent lower than aluminum wear rate under the same test conditions, respectively.

In the present study, composites were prepared by pressured infiltration technique. The employed composites are important in industry due to their higher wear resistance, light in weight and less thermal distortion comparing to conventional composites. Also, wear behavior of Al/B₄C, Al/SiC/B₄C and Al/SiC composites produced by pressured infiltration technique were not studied very much earlier, therefore more explanation about these composites were proposed.

Aluminum alloy is considered an ideal material in aerospace, automobile and other fields because of its lightweight, high specific strength and easy processing. However, low hardness and strength of the surface of aluminum alloys are the main factors that limit their applications. The purpose of this study is to obtain a composite coating with high hardness and lubricating properties by applying GO–PVA over MAO coating.

A pulsed bipolar power supply was used as power supply to prepare the micro-arc oxidation (MAO) coating on 6061 aluminum sample. Then a graphene oxide-polyvinyl alcohol (GO–PVA) composite coating was prepared on MAO coating for subsequent experiments. Samples were characterized by Fourier infrared spectroscopy, X-ray diffraction, Raman spectroscopy and thermogravimetric analysis. The friction test is carried out by the relative movement of the copper ball and the aluminum disk on the friction tester.

Results showed that the friction coefficient of MAO samples was reduced by 80% after treated with GO–PVA composite film.

This research has made a certain contribution to the surface hardness and tribological issues involved in the lightweight design of aluminum alloys.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0427/

This paper aims to develop a specific type of mobile nonrigid support friction stir welding (FSW) robot, which can adapt to aluminum alloy trucks for rapid online repair.

The friction stir welding robot is designed to complete online repair according to the surface damage of large aluminum alloy trucks. A rotatable telescopic arm unit and a structure for a cutting board in the shape of a petal that was optimized by finite element analysis are designed to give enough top forging force for welding to address the issues of inadequate support and significant deformation in the repair process.

The experimental results indicate that the welding robot is capable of performing online surface repairs for large aluminum alloy trucks without rigid support on the backside, and the welding joint exhibits satisfactory performance.

Compared with other heavy-duty robotic arms and gantry-type friction stir welding robots, this robot can achieve online welding without disassembling the vehicle body, and it requires less axial force. This lays the foundation for the future promotion of lightweight equipment.

The designed friction stir welding robot is capable of performing online repairs without dismantling the aluminum alloy truck body, even in situations where sufficient upset force is unavailable. It ensures welding quality and exhibits high efficiency. This approach is considered novel in the field of lightweight online welding repairs, both domestically and internationally.

The military operation of the Russian Federation on the territory of Ukraine exerted additional pressure on prices on the aluminum market since aluminum supplied by Russia accounts for about 10% of the total volume of US imports. It is known that Russia has become the largest aluminum producer after China, and now there is also an increase in aluminum production. Since electricity prices remain relatively low in Russia, especially in energy-surplus Siberia, the increase in output along with the increase in metal prices is a positive factor, since 70% of the primary aluminum produced is exported and only less than a third is consumed domestically. At the same time, high aluminum prices may constrain the expansion of domestic consumption of the metal and may force manufacturers to look for a cheaper alternative. In general, the increase in aluminum prices coincides with the general “supercycle” of raw materials in the last year and a half, and there is a chance to stabilize aluminum prices at current high levels, which will be facilitated, among other things, by new metallurgical projects in Russia. At the same time, it is worth noting that limited metal supplies will haunt the industry for most of 2022, and some experts predict that it may take up to five years to solve the problems.

Aluminum is an exchange commodity. But physical trading of this metal in most cases does not occur on the stock exchange, since more than 90% of aluminum sales with physical delivery occur under direct contracts between producers and buyers of the metal (over-the-counter market). Aluminum as an exchange commodity has standardized consumer properties, namely: the goods are interchangeable, easily transported and stored, and can be divided into batches. That is why upstream products are traded on commodity exchanges, not semifinished products or finished products. When commodity exchanges were first created, they served as a place for concluding physical contracts for the supply of such exchange-traded goods, but with the increase in trading volumes and the development of financial instruments, the role of exchanges has changed. Today, futures contracts for raw materials are traded on them – financial instruments that almost never entail a real physical supply (at the same time, this possibility is not excluded). As a result of the bidding, a price is set that serves as a guideline for producers and consumers around the world.

Purpose – This chapter analyzes two environmental conflicts in Southeast Michigan. It analyzes how activists in each community framed each conflict and what factors prevented the groups from collaborating.

Design/methodology/approach – This essay uses a multi-method approach. Researchers used participant observation, interviews, and archival information gleaned from government documents and newspapers.

Findings – Both community groups had a common opponent – a corporation that had closed its facilities in a predominantly black, low-income urban community and relocated it to a predominantly white, middle-class, rural community. Both communities had complaints about pollution, yet they did not collaborate with each other in their campaigns against the corporation.

Originality/value – The essay blends two theoretical approaches – social movement and conflict theories – to help in the assessment of how the conflicts unfolded and why collaboration between activists in the two communities did not occur. This is one of the first attempts to analyze environmental justice conflicts from this perspective.

The purpose of this paper is to provide acid‐dyes, known for the dyeing of porous aluminum oxide films, as inhibitors of the corrosion of aluminum in neutral chloride solutions.

Potentiodynamic polarization plots are recorded on mechanically pretreated aluminum using a three‐electrode cell containing 0.01 M NaCl solution with or without 0.025 mM of the acid‐dyes monosulfonic methyl orange (MO), disulfonic chromotrop RR (CH), disulfonic alphazurine A (AZ) and trisulfonic light green SF yellowish (LG). The X‐ray fluorescence technique is used in certain cases for the estimation of sulfur net content of the surface of the probes and thus of the concentration of the adsorbed dye.

The inhibition efficiency of acid dyes on corrosion of mechanically pretreated aluminum seems to be related more to the presence of a following quinonoid structure which probably contributes more to the formation of mono‐ or bi‐dentate compounds with the aluminum cations in the substrate than to the number of sulfonic groups in their molecule. Thus, the triphenylmethane dyes LG and, to a greater extent AZ, having this quinonoid structure means they are more efficient as corrosion inhibitors in near‐neutral chloride solution than the azo dyes MO and CH, that do not have it.

Selected acid‐dyes such as triphenylmethane sulfonic‐dyes, which have found wide application in the dyeing industry, seem to protect aluminum against the corrosive action of chlorides.

This paper is intended to be the nucleus for the electrochemical studies of the effectiveness of acid dyes as corrosion inhibitors for aluminum.

The purpose of this paper is to promote the corrosion resistance of the 5083-111H aluminum alloy by laser cleaning.

Laser with 2 ns pulse width was adopted in this project and the corrosion resistance of cleaned samples was tested by copper-accelerated salt spray (CASS). The surface morphology, elemental composition and distribution were then characterized by SEM. Moreover, surface morphology, elemental composition and distribution were also tested.

Results suggested a higher corrosion resistance was successfully obtained by laser cleaning. Compared with samples cleaned by 2000 grit sandpaper, mechanical cleaning resulted in a 53% larger height difference between the peak and valley. The content of the oxygen is 8.85% on the surface cleaned mechanically and the distribution is dependent on the distribution of aluminum whereas that of the laser cleaning sample is 24.41% and the distribution existed even in the Al-poor area.

In this project, the 2-ns laser cleaning was proved to have the capability to remove the oxide layer on the aluminum alloy surface while retaining an excellent corrosion resistance and smooth surface. Meanwhile, a thorough elemental distribution and smaller grain size lead to a smaller difference in elemental concentration. This retards the diffusion of oxygen into the substrate and hence increases the corrosion resistance of the surface.

This study aims to investigate the effect of coatings prepared by the addition of copper-aluminum alloy powder on the corrosion behavior of 90/10 copper-nickel alloy.

Coatings of copper-aluminum alloy powder at different contents (Wt.% = 50%, 60%, 70% and 80%) were prepared by the high-temperature heat treatment process. The microstructure and component of the coatings were characterized by scanning electron microscope, X-ray diffraction, energy dispersive spectrometer and X-ray photoelectron spectroscopy. The electrochemical properties of the coating were explored by electrochemical impedance spectroscopy.

The results show that the aluminized layer was successfully constructed on the surface of 90/10 copper-nickel alloy, the composition of the coating was composed of copper-aluminum phase and aluminum-nickel phase, the existence of the aluminum-nickel phase was formed by the diffusion of Ni elements within the substrate and because of the diffusion, the Al-Ni phase was distributed in the middle and bottom of the coating more. The Al-Ni phase is considered to be the enhanced phase for corrosion resistance. When the copper-aluminum alloy powder content is 70 Wt.%, the corrosion resistance is the best.

The enhancement of corrosion resistance of 90/10 copper-nickel alloy by the copper-aluminum alloy powder was revealed, the composition of the aluminized layer and the mechanism of corrosion resistance were discussed.

The conventional method for evaluation of corrosion resistance of aluminum flakes is based on the volume of evolved hydrogen in acidic and basic environments. This study aims to introduce electrochemical impedance spectroscopy (EIS) as a method to evaluate corrosion resistance of aluminum flakes.

Aluminum flakes with different surface modifications were compressed to build a disk. Then, the disks were examined by EIS in NaCl solution. Also, the corrosion resistance of the flakes was evaluated by the conventional method.

The results revealed applicability of EIS for evaluation of corrosion resistance of aluminum flakes.

Application of EIS to evaluate corrosion resistance of aluminum flakes is novel. As it can provide fast, reliable and quantitative estimation of the corrosion resistance of the aluminum flakes in the 3.5 per cent NaCl solution. This medium is highly encountered for the aluminum flakes used in organic coatings, that is why test in NaCl solution is more convenient compared to the conventional methods using acid and alkaline conditions.