Reliability improvement of gas discharge tube by suppressing the formation of short-circuit pathways

After cumulative discharge of gas discharge tube (GDT), it is easy to form a short circuit pathway between the two electrodes, which increases the failure risk and causes severe influences on the protected object. To reduce the failure risk of GDT and improve cumulative discharge times before failure, this work aims to suppress the formation of two short-circuit pathways by optimizing the tube wall structure, the electrode materials and the electrode structure. A total of five improved GDT samples are designed by focusing on the insulation resistance change that occurs after the improvement; then, by combining these designs with the microscopic morphology changes inside the cavity and the differences in deposition composition, the reasons for the differences in the GDT failure risk are also analyzed. The experimental results show that compared with GDT of traditional structure and material, the method of adding grooves at both ends of the tube wall can effectively block the deposition pathway of the tube wall, and the cumulative discharge times before device failure are increased by 149%. On this basis, when the iron-nickel electrode is replaced with a tungsten-copper electrode, the difference in the electrode’s surface splash characteristics further extends the discharge times before failure by 183%. In addition, when compared with the traditional electrode structure, the method of adding an annular structure at the electrode edge to block the splashing pathway for the particles on the electrode surface shows no positive effect, and the cumulative discharge times before the failure of the two structures are reduced by 22.8% and 49.7% respectively. Among these improved structures, the samples with grooves at both ends of the tube wall and tungsten-copper as their electrode material have the lowest failure risk.

Adiabatic versus non-adiabatic electron transfer at 2D electrode materials

Abstract2D electrode materials are often deployed on conductive supports for electrochemistry and there is a great need to understand fundamental electrochemical processes in this electrode configuration. Here, an integrated experimental-theoretical approach is used to resolve the key electronic interactions in outer-sphere electron transfer (OS-ET), a cornerstone elementary electrochemical reaction, at graphene as-grown on a copper electrode. Using scanning electrochemical cell microscopy, and co-located structural microscopy, the classical hexaamineruthenium (III/II) couple shows the ET kinetics trend: monolayer > bilayer > multilayer graphene. This trend is rationalized quantitatively through the development of rate theory, using the Schmickler-Newns-Anderson model Hamiltonian for ET, with the explicit incorporation of electrostatic interactions in the double layer, and parameterized using constant potential density functional theory calculations. The ET mechanism is predominantly adiabatic; the addition of subsequent graphene layers increases the contact potential, producing an increase in the effective barrier to ET at the electrode/electrolyte interface.

Investigation into the Re-Arrangement of Copper Foams Pre- and Post-CO2 Electrocatalysis

The utilization of carbon dioxide is a major incentive for the growing field of carbon capture. Carbon dioxide could be an abundant building block to generate higher-value chemical products. Herein, we fabricated a porous copper electrode capable of catalyzing the reduction of carbon dioxide into higher-value products, such as ethylene, ethanol and propanol. We investigated the formation of the foams under different conditions, not only analyzing their morphological and crystal structure, but also documenting their performance as a catalyst. In particular, we studied the response of the foams to CO2 electrolysis, including the effect of urea as a potential additive to enhance CO2 catalysis. Before electrolysis, the pristine and urea-modified foam copper electrodes consisted of a mixture of cuboctahedra and dendrites. After 35 min of electrolysis, the cuboctahedra and dendrites underwent structural rearrangement affecting catalysis performance. We found that alterations in the morphology, crystallinity and surface composition of the catalyst were conducive to the deactivation of the copper foams.

Parametric investigation using PSO algorithm while machining TixNiyCoz alloys

In this paper, the research has been focused on machining functional material using electro spark machining process. The Ti x Ni y Co z alloy in three different combinations of Ni and Co (Tix Niy Coz ) as (i) Ti50 Ni49 Co1 (ii) Ti50 Ni45 Co5 and (iii) Ti50 Ni40 Co10 ) were machined with copper electrode wire under electro spark method. The machined samples were subjected to surface characterization techniques using electron microscope, energy dispersive spectra analysis and confocal surface microscope. Also, the amount of material removed was mathematically calculated to infer the performance of the machining process. From the investigation, an increase in Co (wt. %) was found difficult to machine and the surface roughness is a maximum of 4.35 µm at spark gap and servo voltage (125 µs and 20 V) respectively. The particle swarm optimization technique is used to find the globally best solution. The process parameters for machining TixNiyCoz alloy found in the range of 116 – 122 µs and 22 to 32 V, spark bandgap and servo voltage respectively. Therefore, at a maximum pulse on time (spark gap 122 µs) and average servo voltage (30V) TixNiyCoz alloy can be machined with wire electro spark method for best results.