An Electrochemically Activated Nanofilm for Sustainable Mg Anode with Fast Charge Transfer Kinetics

Highly reversible Mg plating/stripping is key for rechargeable Mg batteries and has typically been successfully demonstrated using transient electrochemical techniques such as cyclic voltammetry measurements. However, little effort has been invested in studying the stability of the electrode/electrolyte interface over an extended time. We report here the development an in situ generated surface film for Mg anodes based on electrodeposited bismuth (E_Bi). This film improves the interfacial stability of Mg in contact with the electrolyte, particularly over an extended time, and possesses fast charge-transfer kinetics (< 30 Ω∙cm2) and low non-time-sensitive interfacial film resistance (ca. 5 Ω∙cm2) for active Mg species.

Simulation and experimental investigation of contact spot temperature for electrical contact components

The contact spot temperature of electrical contact components substantially affects the reliability and electrical life of any electrical connections within the electrical engineering. In this paper, finite element model of typical spring structure components is built by using COMSOL Multiphysics software. Furthermore, the transient process of contact temperature is simulated by taking account of film resistance on the contact surface. Moreover, a test rig is introduced that makes it possible to measure the electrical contact resistance and temperature within the electrical contact components simultaneously. Finally, correlation between contact resistance and contact spot temperature with different contact force and current levels are investigated explicitly.

Study of Microwave-Induced Ag Nanowire Welding for Soft Electrode Conductivity Enhancement

Silver nanowire (AgNW)-coated thin films are widely proposed for soft electronics application due to their good conductivity, transparency and flexibility. Here, we studied the microwave welding of AgNW-based soft electrodes for conductivity enhancement. The thermal effect of the microwave to AgNWs was analyzed by dispersing the nanowires in a nonpolar solution, the temperature of which was found to be proportional with the nanowire diameters. AgNWs were then coated on a thin film and welded under microwave heating, which achieved a film conductivity enhancement of as much as 79%. A microwave overheating of AgNWs, however, fused and broke the nanowires, which increased the film resistance significantly. A soft electrode was finally demonstrated using the microwave-welded AgNW thin film, and a 1.13 µA/mM sensitivity was obtained for glucose sensing. Above all, we analyzed the microwave thermal effect on AgNWs to provide a guidance to control the nanowire welding effect, which can be used for film conductivity enhancement and applied for soft and bio-compatible electrodes.

Corrosion Study of Selective Laser Melted IN718 Alloy upon Post Heat Treatment and Shot Peening

Selective laser melted (SLM) IN 718 alloy specimens are subjected to heat treatment and shot peening to assess the effect of post processing on the corrosion performance of the alloy in a 3.5 wt % NaCl solution. The four conditions used in this analysis are as-built material (AB), heat-treated as-built material (HT), shot-peened as-built material (SP), and heat-treated and shot-peened as-built material (HTSP). Microstructural studies revealed the presence of a 500 nm sized cellular structure with a γ matrix surrounded by the Laves phase in the AB material. Shot-peening reduced the surface roughness of the AB and HT samples to almost 80%. The potentiodynamic experiments revealed a highest Icorr value of 0.21 µA/cm2 for the AB material and the lowest Icorr value of 0.04 µA/cm2 for the HTSP material. In the Electrochemical Impedance Spectroscopy (EIS) analysis, the Nyquist plot substantiated the increasing corrosion resistance in the same order of decreasing corrosion rate. The Bode plot exhibited two resistance–capacitance (RC) time constants for all four conditions. The solution resistance measured around 30 Ω, with the HTSP specimen exhibiting the highest passive film resistance of 676 kΩ cm2 and the AB specimen exhibiting the lowest passive film resistance of 234 kΩ cm2. This study has shown that elimination of the network of the Laves phase in SLM material through heat treatment and smooth surface morphology achieved through shot peening improves the corrosion resistance of Inconel 718 alloy.

The Influence of Temperature on the Lateral Photovoltaic Effect in the Fe3O4/SiO2/n-Si Structure

We report on the results of a study of the lateral photovoltaic effect in the Fe3O4/SiO2/n-Si(001) structure at temperatures of 300 and 122 K under continuous and pulsed illumination. It is found that when the temperature changes from 300 to 122 K, the LPE sensitivity decreases from 112 to 65 mV/mm. At pulsed illumination, an increase of rise time and a fall time is observed with decreasing temperature. From a consideration of the energy band diagrams and equivalent circuits of the Fe3O4/SiO2/n-Si structure, it is assumed that the detected temperature effects of LPE are due to the strong dependence of the magnetite film resistance on temperature.