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This work aimed to explore the effect of cBN (cubic boron nitride) content on the microstructures and wear-corrosion resistance of the CoCrFeNiTi0.8-xcBN (x = 0, 2, 4, 6 wt.%) particle-reinforced high-entropy alloy coatings. Laser cladding technology was used to prepare the coatings on TC18 substrate. The microstructures, volume wear rates and polarization curves were characterized. The results showed that the CoCrFeNiTi0.8-xcBN coatings had an optimal forming quality under the process parameters: laser power of 1500 W, scanning rate of 12 mm/s and overlapping rate of 60%. As the cBN content increased, plenty of TiN and TiB2 hard particles formed in situ in the coatings, significantly improved the wear resistance. As a result, the volume wear rate of CoCrFeNiTi0.8-6cBN was only 4.0% and 16.5% of that of TC18 substrate and CoCrFeNiTi0.8 coating, respectively; the wear mechanism changed from adhesive wear + oxidative wear to abrasive wear + oxidative wear gradually. Moreover, CoCrFeNiTi0.8-xcBN coatings can effectively inhibit the infiltration of corrosive media by dense organizational characteristics and the physical barrier effect of oxidation-protective films. After 480 h of neutral salt spray (NSS) test, the CoCrFeNiTi0.8-xcBN coatings exhibited excellent corrosion resistance, both of the appearance and protection rating reached level 10. Therefore, it can be used as the wear-corrosion-resistant coating for the TC18 substrate in a NSS environment. [ABSTRACT FROM AUTHOR]

Co9S8 is a highly promising electrochemically active material for energy devices; its rational design and manufacture for further enhancing the electrochemical activity and durability are still challenging. Herein, Co9S8@CNT compounds are synthesized by one-step pyrolysis, which self-assembled the monomolecular precursor and carbon nanotubes (CNTs). The CNTs effectively improve the electrical conductivity of the materials and availability of the catalytically active sites, which means that the electrochemical ability of Co9S8@CNT is better than that of individual Co9S8 and CNTs. The onset potential of Co9S8@CNT is 132 mV, which has greatly decreased. At the mass current density of 10 mA mg−1, the overpotential is 337 mV, and the Tafel slope is 49.8 mV dec−1. The addition of CNTs makes up for the deficiency of low electrical conductivity of the CoSx. Furthermore, the three-dimensional (3D) structure of the composite improves its electrocatalytically active surface area, and the electrocatalytic ability has been improved efficiently, owing to the increased number of catalytic sites on the surface. [ABSTRACT FROM AUTHOR]

In recent years, a polymer-free fracturing fluid is under research to minimize the conductivity damage in formation and fracture during and after fracturing. Through extensive experiments, we prepared CO2-sensitive wormlike micelles (WLMs) based fracturing fluid system using anionic surfactant NaOA (Sodium Oleate-C18H33NaO2) and TMTAD (2,6,10-trimethyl-2,6,10-triazaundecane-C11H27N3). Rheological results from viscosity variation with steady shear rate using CO2/pH/time-response after CO2 bubbling confirm that the 3NaOA-TMTAD (3:1) was found as the best one in the properties of WLMs structure and the intermolecular interactions when comparing to 1NaOA-TMTAD and 2NaOA-TMTAD. Further, the surface tension after CO2 bubbling shows a good capability to decrease about 27.01 mN·m−1 at a CMC of 0.543 mM. The cryo-TEM test justifies the occurrence of spherical and WLMs in the fluid, before and after CO2 injection. The fluid system presents an outstanding sand suspension and gel breaking property, which are the positive features during the fracturing and flow back period; respectively. Good response with the alternative changes in CO2 pressures possesses an effective influence on shear viscosity using different temperatures (25 and 85 °C) and shear rates (20, 170, and 200 s−1). Also, the results of a linear relationship and low filtration coefficients verify that the fluid system has good filtration property. Such an easy and environmentally benign fluid system may be involved as a potential candidate in fracturing in unconventional hydrocarbon reservoirs, to reduce the formation damage which is usually very common in the polymer-based fracturing fluid. [ABSTRACT FROM AUTHOR]

Transitional metal oxides have attracted increasing attention as the most promising anode material for lithium-ion batteries (LIBs). However, due to the poor ionic conductivity and great structural changes in the process of Li+ insertion and extraction, the performance of the pristine materials in batteries still has a far way to go to satisfy requirements. In this article, using spherical ZIF-12 as a pyrolysis precursor, two Co3O4 hollow core-shell carbon nanocomposites (CHS@C and CHS@CG) were fabricated via a molecular precursor pyrolysis strategy. The synergistic effect of the yolk-shell hollow nanosphere structure shortens the diffusion path of ions, increases the contact area between the electrode and electrolyte, and provides a buffer space for the volume change in the electrochemical reaction. Both materials have excellent structural stability and good electrical conductivity. In comparison, the performance of CHS@CG is better, and the reversible specific capacity reaches 831 mAh·g−1 at 0.2 C after 400 cycles. In the galvanostatic charge–discharge process, the Coulombic efficiency reaches nearly 100%, exhibiting a good reversible cycle. The synthesis method of these electrode materials can provide a reference for making other energy storage equipments. [ABSTRACT FROM AUTHOR]

Soliton microcombs, offering large mode spacing and broad bandwidth, have enabled a variety of advanced applications, particularly for telecommunications, photonic data center, and optical computation. Yet, the absolute power of microcombs remains insufficient, such that optical power amplification is always required. Here, we demonstrate a combined technique to access power-sufficient optical microcombs, with a photonic-integrated soliton microcomb and home-developed erbium-doped gain fiber. The soliton microcomb is generated in an integrated Si 3 N 4 microresonator chip, which serves as a full-wave probing signal for power amplification. After the amplification, more than 40 comb modes, with 115-GHz spacing, reach the onset power level of >−10 dBm, which is readily available for parallel telecommunications , among other applications. [ABSTRACT FROM AUTHOR]

Palladium‐catalyzed cross‐dehydrogenative coupling of 3‐benzoyl substituted coumarins through C−H activation is described to synthesize indeno[2,1‐c]chromene‐6,7‐diones. A broad range of indeno[2,1‐c]chromene‐6,7‐diones using this method could be easily achieved in moderate to good yields (up to 93%). [ABSTRACT FROM AUTHOR]