Cobalt is a good material for catalysis, energy, and many other applications. In this study, a cobalt coating was prepared by applying electrodeposition in an ethylene carbonate (EC) -AlCl 3 -CoCl 2 electrolyte system at 333 K. The electrical conductivity of the 0.97EC-0.02AlCl 3 -0.01CoCl 2 system at 318–363 K varied with the temperature based on the following relation: σ = 70.3876 – 0.4035 T + 6.4394 × 10 −4 T 2 (µS/cm). Cyclic voltammetry and chronoamperometry analyses showed that the electrodeposition of cobalt was an irreversible process, and controlled by diffusion. The diffusion coefficient was 1.92 × 10 −8 cm 2 /s. Cobalt coating was achieved by applying electrodeposition under different conditions at − 0.4 to − 0.7 V (vs. Ag/AgCl). The cobalt coating electrodeposited at − 0.5 V for 2 h was found to be dense, with a grain size of 0.5 µm. Graphical Abstract
Composite powder of tungsten carbide with nano-cobalt coatings was successful manufactured via a novel sol-gel process, and coarse grained WC-4 wt% Co cemented carbide was produced from the cobalt-coated WC powder. Phase composition and microstructure evaluation were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results revealed that the WC particles were completely encased in the CoC 2 O 4 layers by the sol-gel process. Core-shell structured WC-4 wt% Co composite powder was subsequently prepared by reducing the WC-CoC 2 O 4 precursor powder in hydrogen atmosphere. The morphology and crystal structure of the cobalt-coating were found to depend on the reduction temperature. Chemical analyses revealed that the WC-Co composite powders were non-contaminated and composition-controllable. WC-4 wt% Co cemented carbide fabricated from the cobalt-coated WC composite powder showed a refined and uniform microstructure, and therefore improved mechanical properties , compared to the cemented carbide made by ball-milled WC-Co powder. The transverse rupture strength was 2249 MPa in the cemented carbide from the cobalt-coated WC powder, compared to 1871 MPa of the carbide made by the ball-milling powder.
Li Sun,Mengying Sun,Yuan Zhi,Hua Zhang,Yuejin Shan,Binlin Dou,Jian Chen,Lixin Zhang
The continuous-flow (C-F) reduction process has been limitedly applied in the treatment of dyeing wastewater owing to the weak catalytic performance of the reactors employed. In this work, a small tubular packed reactor and its module are designed, fabricated and used for the C-F reduction of nitro and azo compounds in dyeing wastewater. Here, Au–Co–CoOx-coated glass beads with superior catalytic activity are chosen as packing materials, prepared without any toxic chemical agents. By means of the reactor, 4-nitrophenol (4-NP) can be completely removed and its removal rate is determined to be 100 μmol h−1. After that, a novel strategy for the tandem module is proposed to further enhance the removal rate of 4-NP. Based on the tandem module, the removal rate of 4-NP can be dramatically boosted to 1900 μmol h−1. Meanwhile, the rate constant for the C-F reduction of 4-NP can reach up to 0.44 s−1. Furthermore, the tandem module displays satisfactory operating stability, reusability and reliability in real water samples. In addition, the tandem module first achieves the C-F reduction of 2-nitrophenol, 3-nitrophenol, methyl red and methyl orange. Clearly, the reactor and its module can effectively extend the application of the C-F reduction process in dyeing wastewater treatment.
危险品化学品经营许可证（带存储）