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The reaction behavior between La‐bearing FeCrAl melt and CaO–SiO2‐based slags is quantitatively characterized based on industrial sampling, slag‐steel reaction simulation experiment, mass balance calculation, and thermodynamic theoretical analysis. In the results, it is shown that compared with FeCrAl melt, [La] in La‐bearing FeCrAl melt not only reacts with SiO2 in slags, but also promotes the reaction of [Al] with SiO2 and Na2O. The percentage of mass change of [La] after reaction with CaO–SiO2–Na2O–Al2O3 and CaO–SiO2–CaF2–Al2O3 slag is the highest increased by 92.43 wt%, and that of [Al] is the highest increased by 4.68 wt%. The percentages of mass change of SiO2, Na2O, and Al2O3 are the highest increased by 9.48, 2.91, and 52.86 wt%, respectively. Thermodynamic analysis shows that in FeCrAl melt, La not only increases the activity of itself, but also enhances the activity of Al to a certain extent, which is conducive to increasing the reaction degree between [Al] and Na2O and SiO2 in CaO–SiO2‐based slags. Moreover, the reaction behavior of CaO–SiO2–Na2O–Al2O3 and CaO–SiO2–CaF2–Al2O3 slags is compared and the main reasons are analyzed. The results of slag‐steel reaction simulation experiment are consistent with the trend of composition change of the mold flux in industrial sampling. [ABSTRACT FROM AUTHOR]

The present study investigated the surface morphology, phase composition, mechanical properties, and corrosion resistance of Ni-W alloy coatings prepared under current densities of 1–5 A/dm², after undergoing heat treatment at 400 °C, 600 °C, and 900 °C. The grain size of the as-plated Ni-W alloy coating was below 10 nm. After heat treatment at different temperatures, the grain size increased, reaching a maximum value of around 30 nm at 900 °C. Heat treatment crystallized and altered the structure of the coating. Different heat treatment temperatures yielded different precipitates, including Ni4W, Ni6W6C, and WC. The highest coating hardness (820–940 Hv) was achieved at 400 °C, while the best corrosion resistance was achieved at 600 °C. The precipitation hardening phase can be obtained by proper heat treatment temperature, yielding the desired properties of the composite coating. [ABSTRACT FROM AUTHOR]

The degradation of titanium diboride (TiB2)/titanium carbide (TiC) composites in the liquid Nd and molten NdF3–Nd2O3–LiF salts is investigated at 1,060 °C, respectively. The penetration of TiB2/TiC composites by liquid Nd mainly depended on the grain boundaries and residual pores, even if the coherent interface is formed between TiB2 and TiC. The oxidation of TiB2 led to further interfacial chemistry reactions, which speeded up the degradation of TiB2/TiC composites at the initial stage in NdF3 –LiF–Nd2O3 system. After that, the degradation was slowed because of the formation of diffusion boundary layer, and then chemical penetration was replaced gradually by the physical penetration. The dissolved Ti in liquid Nd and NdF3–LiF–Nd2O3 melts are used to evaluate the corrosion rate of TiB2/TiC composites, and the calculated values were about 0.56 and 7.8 mm/year, respectively. After the penetration by liquid Nd and NdF3–LiF–Nd2O3 melts, the bending strengths of TiB2/TiC composites decreased and the fracture mode changed from transgranular to intergranular due to the decreased grain boundary force.

Due to the demand of an efficient, inexpensive and scalable synthesis of an oxygen reduction reaction (ORR) catalyst for practical application in fuel cells, we demonstrate a facile strategy to fabricate the flexible Co3O4-C/C3N4 catalyst. The results show that Co3O4-C/C3N4 exhibits a remarkably enhanced ORR electrocatalytic activity due to the introduction of Co and carbon nanodots (CDots) into the graphitic carbon nitride (g-C3N4) sheet. The electron-transferred number of Co3O4-C/C3N4 toward ORR is calculated to be about 3.69, suggesting a desirable four-electron pathway. Furthermore, Co3O4-C/C3N4 shows better durability and tolerance to methanol crossover effects than the commercial platinum (Pt)/C catalyst, indicating a promising potential as an ORR electrocatalyst in practical applications.

A cobalt/nitrogen/carbon (Co/N/C) electrocatalyst has been successfully synthesized by the solvothermal method using cobalt acetate (Co(Ac)2), NH3·H2O and carbon quantum dots (CQDs) as the starting materials. The oxygen reduction reaction (ORR) activity of Co/N/C is better than single nitrogen-doped CQDs (NC) or cobalt-doped CQDs in terms of the onset potential and peak potential. The Co/N/C catalyst also exhibits better methanol durability and stability compared to the commercial Pt/C (20%). The electron-transferred number of Co/N/C for ORR is calculated to be about 3.51, indicating a four-electron pathway. Such a novel and high-efficient codoped carbon-based catalyst could be a promising substitute for commercial Pt/C in fuel cells as well as other energy storage and conversion systems.

The influence of Ca treatment, Mg treatment and Ca–Mg combined treatment on the inclusions in 45MnVS non-quenched and tempered steel were studied in the present work. After the melting experiment, a hot rolling test was carried out on the steel ingot. Additionally, the composition, quantity and morphology of inclusions in the test steel samples were analyzed by automatic scanning electron microscopy (ASPEX) and an energy dispersive X-ray spectrometer connected to scanning electron microscope (SEM-EDS). The results indicated that the inclusions in 45MnVS steel mainly consisted of a large amount of sulfides and a small amount of oxides. Sulfide inclusions could be nucleated and precipitated using oxides as a core during solidification. The proportion of spindle-shaped inclusions in sulfide with smaller sizes was higher. The sizes of MnS–oxide inclusions were larger than those of MnS. After hot rolling, the proportion of spindle-shaped MnS and complex sulfides with oxide cores in the samples was increased significantly. Compared with Ca treatment and Ca–Mg treatment, more oxides were formed in the steel with Mg treatment, which can in turn become the cores for sulfide nucleation and precipitation. Thus, the proportion of MnS–oxide inclusions in steel increased. Compared with Ca treatment and Mg treatment, steel with Ca–Mg treatment was more conducive to the formation of complex sulfides, and increased the proportion of spindle-shaped sulfides in 45MnVS steel. After Ca treatment, Mg treatment and Ca–Mg combined treatment, the proportions of spindle-shaped sulfides in steel were 23.31%, 19.39% and 43.24%, respectively. [ABSTRACT FROM AUTHOR]

Reduced graphene supported Co‐Sn‐Pd nanoparticle catalysts(Co0.2SnxPdy/rGO, x + y = 0.4) were successfully synthesized by reducing the trace amounts of ions (Pd2+, Sn2+, and Co2+) in the presence of reduced graphene via an ultrasonic irradiation method. Characterization of the Co0.2SnxPdy/rGO catalysts by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) indicates that the Co0.2Sn0.2Pd0.2/rGO catalyst with a mean diameter of ~3.8 nm is close to a single‐phase solid solution. X‐ray photoelectron spectroscopy (XPS) shows the binding energy of metallic Pd shifts to a higher angle in the Co0.2SnxPdy/rGO (x + y = 0.4) catalysts, indicating a shift of Pd electronic centre upon alloying with Co and Sn. Conventionally, ternary Co‐Sn‐Pd/rGO catalysts show greater oxygen reduction reaction (ORR) activities and durability than binary Pd‐Co/rGO catalyst and 20 wt% Pt/C catalyst even at a very low Pd content. Among of the synthetic catalysts, the Co0.2Sn0.2Pd0.2/rGO catalyst exhibits the best ORR activity (E1/2 = 0.91 V, k = −57 mV · dec−1) and dominates a 4‐electron pathway in the ORR process (n = 3.95 ± 0.09, H2O2<4%). Also, the Co0.2SnxPdy/rGO (x + y = 0.4) catalysts display a remarkable advantage of high methanol tolerance compared to that of the commercial 20 wt% Pt/C catalyst, which make them potential candidates for direct methanol fuel cells. [ABSTRACT FROM AUTHOR]