Discrete Oxidation of a Hard Carbide Tool

Comparative investigations of the effect of discrete surface hardening by standard ion-plasma technology and discrete oxidation technology on the structure and hardness of high-speed steels are carried out. It is shown that, after hardening in the ion-plasma installation on the surface and in the thickness of the layer, droplet-shaped defects, craters and bundles are formed. Metallographic studies showed that the hardened discrete oxidation layer after repeated hardening has a dense, uniform structure. It has been established that the discrete oxidation technology allows to increase the wear resistance of a complex-profile cutting tool 2 times more, compared to a tool hardened by standard ion-plasma technology after regrinding.

An ultra-lithiophilic oxidation layer in a Ni-foam-based anode for lithium metal batteries

An ultra lithiophilic and highly electrical conductive NiO layer was epitaxially grown on the Ni-foam surface by oxidation in air. Oxidizing the Ni-foam in air remarkably increases the wettability of molten Li on the Ni surface.

Effect of Chloride Ions on the Electrochemical Oxidation of Chalcopyrite at 340 °C and 21 MPa

Understanding the oxidative mechanisms of chalcopyrite in various hydrothermal fluids is of great significance to improve copper extraction and to model the geochemical cycling of copper, iron, and sulfur. This paper investigated the effect of NaCl on the electrochemical oxidation of chalcopyrite at 340 °C and 21 MPa using polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. The experimental results showed that NaCl can promote chalcopyrite leaching. As NaCl concentration increases, the protective property of the oxidation layer degraded. In the absence of NaCl, the oxidation layer that consisted of CuSn, (n ≥ 1), probably with some Fe2O3 and Fe(OH)3 and also in the presence of NaCl, Fe2O3, is the principal oxidation product. More rapid ionic diffusion and further chemical reaction contributed to the improvement of chalcopyrite dissolution with increasing NaCl concentration. A dissolution mechanism is proposed in this paper to explain the chalcopyrite leaching processes which is dependent on NaCl concentration.

Performance-Enhanced Triboelectric Nanogenerator Based on the Double-Layered Electrode Effect

Recently, studies on enhancing the performance of triboelectric nanogenerators (TENGs) by forming nanostructures at the contacting interface have been actively reported. In this study, a double-layered bottom electrode TENG (DE-TENG) was successfully fabricated using a metal deposition layer after the water-assisted oxidation (WAO) process. As previously reported, the WAO process for the enhancement of electrical performance increases the effective contact area with an inherent surface oxidation layer (Al2O3). As a new approach for modifying deficiencies in the WAO process, a metal deposition onto the oxidation layer was successfully developed with increased device output performance by restoring the surface conductivity. The proposed metal–dielectric–metal sandwich-structured DE-TENG generated approximately twice the electrical output generated by the WAO process alone (WAO-TENG). This dramatically improved electrical output was proven by a theoretical demonstration based on a double capacitance structure. In addition, the double capacitance structure was confirmed with the aid of a field emission scanning electron microscope. The optimal point at which the DE-TENG generates the highest electrical outputs was observed at a specific Cu layer sputtering time. The exceptional durability of the DE-TENG was proved by the 1 h endurance test under various relative humidity conditions. The potential of a self-powered force sensor using this DE-TENG is demonstrated, having a comparably high sensitivity of 0.82 V/N. Considering its structure, increased electrical energy, easy fabrication, and its durability, this novel DE-TENG is a promising candidate for the self-powered energy harvesting technology in our near future.