Iskanje po repozitoriju

A+ | A- | | SLO | ENG

Ključne besede: structural steel, siloxane polybutyl methacrylate sol-gel, curing temperature, thickness, porosity
Objavljeno v DiRROS: 23.04.2025; Ogledov: 68; Prenosov: 38
Celotno besedilo (5,31 MB)
Gradivo ima več datotek! Več...

Povzetek: This study explores the mechanical and corrosion properties of yttria-reinforced 316L stainless steel. Powder precursor materials were prepared using mechanical alloying. Varying yttria (Y2O3) contents (1, 3, and 5 wt%) were used to assess its impact on the steel’s properties. X-ray diffraction and scanning electron microscopy confirmed the successful dispersion of Y2O3 within the matrix, with the formation of chromium carbides during spark plasma sintering (SPS). The mechanical properties, including hardness and compressive yield strength, improved with increasing Y2O3 contents, with the highest strength observed in the 316L-5Y2O3 sample. However, corrosion resistance decreased with higher yttria concentrations. The 3 wt% Y2O3 sample exhibited the highest corrosion rate due to localized corrosion in areas enriched with oxide particles and chromium carbides. Electrochemical testing revealed that carbide formation and Cr-depleted regions from SPS processing contributed to the corrosion behaviour. These findings suggest that while yttria reinforcement enhances mechanical strength, optimizing the Y2O3 content and processing methods is crucial to balance both mechanical and corrosion performance in ODS 316L stainless steel.
Ključne besede: mechanical milling, SPS, 316L, austenitic stainless steel, yttria, ODS steel, corrosion, EPR-SL
Objavljeno v DiRROS: 31.01.2025; Ogledov: 197; Prenosov: 131
Celotno besedilo (10,37 MB)
Gradivo ima več datotek! Več...

Povzetek: This research aimed to investigate the potential of using alkali activation technology to valorize steel slag and bauxite residue for the production of high-performance pavement blocks. By utilizing these industrial by-products, the study seeks to reduce their environmental impact and support the development of sustainable construction materials. Lab-scale testing showed that bauxite pavers showed a decrease in mechanical strength with increasing replacement of ordinary Portland cement. Partial replacement up to 20% still exceeded 30 MPa in compressive strength. Steel slag-based pavers achieved the 30 MPa threshold required for the application with selected mix designs. Pilot-scale production-optimized formulations and standards testing, including freeze–thaw resistance, confirmed the technical viability of these products. Life cycle analysis indicated a 25–27% reduction in CO2 emissions for slag-based tiles compared to traditional concrete tiles. Moreover, using industrial residue reduced mineral resource depletion. This study examined the properties of the resulting alkali-activated binders, their ecological benefits, and their performance compared to conventional materials. Through a comprehensive analysis of these applications, our research promotes the circular economy and the advancement of sustainable construction products.
Ključne besede: alkali-activated materials, building materials, bauxite residue, steel slag, pavers
Objavljeno v DiRROS: 20.01.2025; Ogledov: 252; Prenosov: 126
Celotno besedilo (4,04 MB)
Gradivo ima več datotek! Več...

Povzetek: Stainless steel production typically follows the duplex process, beginning with the electric arc furnace (EAF) and proceeding to the vacuum oxygen decarburizer (VOD) or argon oxygen decarburizer (AOD). The EAF's role is to melt the charge and heat it up for further processing, reducing tap-to-tap times through partial oxidation. However, this partial oxidation in the EAF leads to chromium losses as oxygen interacts with the high chromium steel melt. To address this issue, parameters affecting chromium burn-off have been identified and presented. A primary challenge in EAF steel production with elevated chromium content is to lower carbon levels while maximizing chromium yield in the melt. Unlike VOD and AOD processes, which permit low carbon and high chromium levels through vacuum or argon blowing, the EAF provides limited protection, mainly through silicon. At higher temperatures, carbon oxidation predominates, hence it is important to limit oxygen input into the system in the initial stages, while “protecting” the chromium with silicon. During the oxidation phase of the steel melt, carbon content decreases; however, attention must be paid to ensure that the concentration is not too low, as this increases chromium activity in the melt, leading to more intense oxidation. A practical model, derived from thermodynamic calculations, has been developed to guide carbon, chromium, and other element oxidation during scrap melting. This model, validated through industrial trials, aids in optimizing steel melt oxidation to minimize chromium losses effectively.
Ključne besede: EAF, stainless steel scrap, carbon oxidation, chromium oxidation, thermodynamics
Objavljeno v DiRROS: 16.01.2025; Ogledov: 236; Prenosov: 104
Celotno besedilo (706,28 KB)
Gradivo ima več datotek! Več...

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: 248; Prenosov: 139
Celotno besedilo (19,42 MB)
Gradivo ima več datotek! Več...