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With the development of aerospace, Mg-Gd-Y-Zn-Zr alloy as a high-performance light alloy has attracted much attention. In this paper, the Mg-8.8Gd-3.9Y-0.85Zn-0.45Zr (wt%, GWZ941) alloy single-pass multilayer components fabricated by cold metal transfer wire and arc additive manufacturing (CMT-WAAM) in CMT mode, CMT-P mode and CMT-Advance mode. Studying the effects of the three CMT characteristics on voltage and current waveforms and metal transfer behaviors of the deposition processes for the GWZ941 alloy. The macro morphology, defect distribution, microstructure, and mechanical properties of the three as-deposited samples were compared. The GWZ941 alloy deposit fabricated by CMT-WAAM exhibits a uniform equiaxed grain structure whose average grain size of the three samples was 11.9 μm, 13.9 μm, and 7.9 μm, with the porosity less than 0.01%. The UTS and EL of the three GWZ941 alloy samples were 257 ± 4 MPa and 7.5 ± 1%, 230 ± 8 MPa and 3.5 ± 1%, 253 ± 2 MPa and 7.0 ± 0.3%, respectively. In the presence of oxide particles in the GWZ941 alloy formed by CMT-WAAM, the oxide content is less than 0.08%, which is the main influencing factor for the reduced strength and plasticity of the GWZ941 alloy.

A detailed study of the pulsed triple-wire gas indirect arc (TW-GIA) welding process based on the arc deflection effect was carried out in this article. The arc anode deflection mechanism, the effect of pulse parameters on weld forming and efficient welding process were systematically studied. The results showed that the special annular electric field and the non-uniform magnetic field were the main reasons for the indirect arc deflection to the anode. When the main wire acted as the anode and the side wires acted as the cathode, the two indirect arcs would deflect synchronously toward the main wire and couple into one arc with high energy density and larger arc stiffness. The arc length and welding depth can be controlled by adjusting the pulse parameters. A stable and efficient single-pass pulsed TW-GIA welding process for a 10 mm Q235 steel plate was developed. The fusion of the side wall of the welded joint was very good, the average tensile strength reached 471.2 Mpa and all joints broke in the base metal.

Constructing novel functional photocatalysts represents a promising approach to optimize the energy band structure and facilitate the separation of photogenerated carriers. Layered double hydroxides (LDHs) exhibit notable advantages in photocatalysis due to the exceptional photoelectrochemical properties and elevated number of active surface atoms. However, an unsuitable band gap and limited carrier migration have inhibited their development in photocatalysis. Herein, we propose a novel in situ topological vulcanization strategy for optimizing the photocatalytic activity of ZnAl LDH-derived sulfides (ZnAlSx). The subsequent etching process via a 1 M NaOH solution was introduced to construct the ZnSxphotocatalysts. Then, the crystallinity of the crystals was enhanced by etching to further improve the catalytic activity and stability of ZnSx. The as-synthesized ZnSxshows an excellent photocatalytic hydrogen production rate (11.89 mmol/g/h) and tetracycline degradation efficiency (91.94%) under light illumination, and its hydrogen evolution efficiency is approximately 176 and 2 times greater than that of ZnAl LDH and ZnAlSx, respectively. The characterization and density functional theory (DFT) analysis confirmed that the surface electronic properties and energy band structure of ZnAl LDH were significantly optimized after experimental treatment, resulting in enhanced carrier separation and photooxidative reduction capacity. Combining in situ topological vulcanization and etching to realize the functional conversion of ZnAl LDH provides promising insights into the construction of high-performance, low-cost photocatalysts.

Triple-wire gas indirect arc (TW-GIA) welding is a new type of welding method. In the TW-GIA welding process, the workpiece is not connected to the power source, and the arc is built between the three wires. In this essay, the arc stability and bead forming of the high-speed TW-GIA welding are studied under a new wire arrangement. Results show that with the increasing of the welding currents, the range of voltage and current fluctuations are reduced during the welding process, and the arc stability is improved. The reason is that increasing current can stabilize the droplet transfer. Since the arc is built between the welding wires, the influence of welding speed on the arc stability of TW-GIA welding is limited. Compared with traditional gas metal arc welding, TW-GIA welding has the characteristics of high deposition rate and low dilution rate, which is helpful for increasing welding speed. The welding speed of 2 mm-thickness steel plate can reach 2.8 m/min by using TW-GIA welding.

This study presents a modified triple-wire indirect arc welding method to improve melting efficiency of the base metal. To achieve this, a mirror-symmetrical wire arrangement was adopted because of small arc distribution space and the electrode polarity is changed different from the previous triple-wire indirect arc welding method. The arc shape is observed with the novel wire arrangement, and the bead-on-plate welding experiments arecarried out and the melting efficiency of the base metal was calculated. Results reveal that the adopting welding wire polarity of the main wire and the side wire respectively acting as anode and cathode can superimpose the two indirect arcs into a single indirect arc which increases the arc energy concentration. The main reason is that the indirect arcs deflect to the main wire and the arc voltage is improved. As a result, the penetration, the melting area and the melting efficiency of the base metal are improved to varying degrees with increasing current. For instance, at the current is 400A, they were increased to 2 times, 3 times and 2.55 times, respectively. Meanwhile, a single pass butt joint of 10mm plates by the modified triple-wire indirect arc welding with low energy consumption and high efficiency is successfully accomplished.