Reversible oxygen reactions in Zn–air batteries require cost‐effective and highly‐active bifunctional electrocatalysts to substitute traditional noble‐metal based catalysts. Herein, a new and promising electrocatalytic material, ternary CoIn2S4 thiospinel, is demonstrated for effectively catalyzing oxygen reduction and oxygen evolution reactions (ORR and OER) with S‐doped reduced graphene oxide (S‐rGO) as an electronic conductor. Compared with Co9S8/S‐rGO (without In doping), the newly developed CoIn2S4/S‐rGO reveals superior electrocatalytic properties for the ORR (half‐wave potential of 0.83 V) and OER (overpotential of 0.37 V at 10 mA cm−2), demonstrating that the introduction of In can promote the reversible oxygen electrode reactions of CoIn2S4. The superior experimentally‐observed electrocatalytic properties are corroborated via density function theory investigations. Meanwhile, the synergistic improvements in the bifunctional activities resulting from the combination of CoIn2S4 and S‐rGO are also confirmed. As a proof of concept, home‐made Zn–air cells are assembled with CoIn2S4/S‐rGO as an air‐cathode. The developed Zn–air cells exhibit a high peak power density (133 mW cm−2) with an energy density of 951 Wh kgZn−1 and robust cycling stability over 150 cycles for 50 h, exceeding of those commercial Pt/C+RuO2 which highlights the practical viability of CoIn2S4/S‐rGO for rechargeable Zn–air batteries.
A multi-strand composite welding wire was applied to join high nitrogen austenitic stainless steel, and microstructures and mechanical properties were investigated. The electrical signals demonstrate that the welding process using a multi-strand composite welding wire is highly stable. The welded joints are composed of columnar austenite and dendritic ferrite and welded joints obtained under high heat input and cooling rate have a noticeable coarse-grained heat-affected zone and larger columnar austenite in weld seam. Compared with welded joints obtained under the high heat input and cooling rate, welded joints have the higher fractions of deformed grains, high angle grain boundaries, Schmid factor, and lower dislocation density under the low heat input and cooling rate, which indicate a lower tensile strength and higher yield strength. The rotated Goss (GRD) ({110}⟨1 1 ¯ 0⟩) orientation of a thin plate and the cube (C) ({001}⟨100⟩) orientation of a thick plate are obvious after welding, but the S ({123}⟨63 4 ¯ ⟩) orientation at 65° sections of Euler’s space is weak. The δ-ferrite was studied based on the primary ferrite solidification mode. It was observed that low heat input and a high cooling rate results in an increase of δ-ferrite, and a high dislocation density was obtained in grain boundaries of δ-ferrite. M23C6 precipitates due to a low cooling rate and heat input in the weld seam and deteriorates the elongation of welded joints. The engineering Stress–strain curves also show the low elongation and tensile strength of welded joints under low heat input and cooling rate, which is mainly caused by the high fraction of δ-ferrite and the precipitation of M23C6.
A novel route was investigated for the preparation of metal injection moulding (MIM) titanium alloys by TiH 2 powder. It can be known from the analysis of thermodynamics and kinetics of dehydrogenation reaction that decomposition occurs when hydrogen partial pressure is y10 22 Pa at 300uC. The temperature range of dehydrogenation is within that of debinding so that the dehydrogenation and debinding can be carried out simultaneously. The hydrogen content of the sample debound in 10 22 Pa is merely 0 . 016 wt-% as the temperature raised up to 525uC, indicating that the hydrogen can be removed effectively. Finally, the sintered parts with average tensile strength of 770 MPa and specific elongation of 4 . 3% were prepared, of which the impurity contents were satisfactory. The sintered parts have the uniform fully lamellar microstructure, in which the interlamellar spacing between a phases is thin.
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