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Povzetek: Electrochemical water-splitting is a promising green technology for the production of hydrogen. One of the bottlenecks, however, is the oxygen evolution half-reaction (OER), which could be overcome with the development of a suitable electrocatalyst. Recently, non-noble metal, high-entropy oxides (HEO) have been investigated as potential OER electrocatalysts, but complex synthesis approaches that usually produce the material in powder form limit their wider utilization. Here, an innovative synthesis strategy of formulating a nanostructured (CoFeNiMnCr)3O4 HEO thin film on a CoFeNiMnCr high entropy alloy (HEA) using facile electrochemical and thermal treatment methods is presented. The CoFeNiMnCr HEA serves as exceptional support to be electrochemically treated in an ethylene glycol electrolyte with ammonium fluoride to form a rough and microporous structure with nanopits. The electrochemically treated CoFeNiMnCr HEA surface is more prone to oxidation during a low-temperature thermal treatment, leading to the growth of a spinel (CoFeNiMnCr)3O4 HEO thin film. The (CoFeNiMnCr)3O4 HEO exhibits a superior overpotential of 341 mV at 10 mA cm−2 and a Tafel slope of 50 mV dec−1 along with remarkable long-term stability in alkaline media. The excellent catalytic activity and stability for the OER can serve as a promising platform for the practical utilization of (CoFeNiMnCr)3O4 HEO.
Ključne besede: electrochemical water-spliting, electrocatalysts
Objavljeno v DiRROS: 20.12.2024; Ogledov: 44; Prenosov: 16
Celotno besedilo (2,75 MB)
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Ključne besede: strategic connectivity areas, structural connectivity, sensitivity analysis, fragmentation use, land-use, Alps Dinaric Mountains
Objavljeno v DiRROS: 20.12.2024; Ogledov: 45; Prenosov: 9
Celotno besedilo (7,21 MB)

Povzetek: Adhesive bonding has proven to be a reliable method of joining materials, and the development of new adhesives has made it possible to use bonding in a variety of applications. This article addresses the challenges of bonding metals such as the aluminum alloy EN AW-5754 and the stainless steel X5CrNi18-10. In this study, the effects of laser cleaning and texturing on the surface properties and strength of two bonded joints were investigated and compared with mechanical preparation (hand sanding with Scotch-Brite and P180 sandpaper). The bonded joints were tested with three different epoxy adhesives. During the tests, the adhesion properties of the bonded surface were determined by measuring the contact angle and assessing the wettability, the surface roughness parameters for the different surface preparations, and the mechanical properties (tensile lap-shear strength). Based on the strength test results, it was found that bonded joints made of stainless steel had 16% to 40% higher strength than aluminum alloys when using the same adhesive and surface preparation. Laser cleaning resulted in maximum shear strength of the aluminum alloy bond, while the most suitable surface preparation for both materials was preparation with P180 sandpaper for all adhesives.
Ključne besede: adhesive bonding, surface preparation, aluminum alloy AW-5754, stainless steel X5CrNi18-10, epoxy adhesives
Objavljeno v DiRROS: 20.12.2024; Ogledov: 42; Prenosov: 18
Celotno besedilo (19,42 MB)
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Povzetek: Using a meshless method, a simulation of steel billets in a pusher-type reheating furnace is carried out for the first time. The simulation represents an affordable way to replace the measurements. The heat transfer from the billets with convection and radiation is considered. Inside each of the billets, the heat diffusion equation is solved on a two-dimensional central slice of the billet. The diffusion equation is solved in a strong form by the Local Radial Basis Function Collocation Method (LRBFCM) with explicit time-stepping. The ray tracing procedure solves the radiation, where the view factors are computed with the Monte Carlo method. The changing number of billets in the furnace at the start and the end of the loading and unloading of the furnace is considered. A sensitivity study on billets' temperature evolution is performed as a function of a different number of rays used in the Monte Carlo method, different stopping times of the billets in the furnace, and different spacing between the billets. The temperature field simulation is also essential for automatically optimizing the furnace’s productivity, energy consumption, and the billet’s quality. For the first time, the LRBFCM is successfully demonstrated for solving such a complex industrial problem.
Ključne besede: pusher-type reheating furnace, steel, temperature field, radiation, convection, diffusion, strong form meshless method, radial basis functions
Objavljeno v DiRROS: 20.12.2024; Ogledov: 41; Prenosov: 17
Celotno besedilo (4,35 MB)
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Ključne besede: groundwater, WTP (water treatment plant), parameters, drinking water quality, water quality index, CCME (Canadian Council of Ministers of the Environment)
Objavljeno v DiRROS: 19.12.2024; Ogledov: 51; Prenosov: 19
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