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Search Results (1,717)

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23 pages, 12015 KiB  
Article
Strain-Controlled Thermal–Mechanical Fatigue Behavior and Microstructural Evolution Mechanism of the Novel Cr-Mo-V Hot-Work Die Steel
by Yasha Yuan, Yichou Lin, Wenyan Wang, Ruxing Shi, Chuan Wu, Pei Zhang, Lei Yao, Zhaocai Jie, Mengchao Wang and Jingpei Xie
Materials 2025, 18(2), 334; https://doi.org/10.3390/ma18020334 - 13 Jan 2025
Abstract
In response to the intensifying competition in the mold market and the increasingly stringent specifications of die forgings, the existing 55NiCrMoV7 (MES 1 steel) material can no longer meet the elevated demands of customers. Consequently, this study systematically optimizes the alloy composition of [...] Read more.
In response to the intensifying competition in the mold market and the increasingly stringent specifications of die forgings, the existing 55NiCrMoV7 (MES 1 steel) material can no longer meet the elevated demands of customers. Consequently, this study systematically optimizes the alloy composition of MES 1 steel by precisely adjusting the molybdenum (Mo) and vanadium (V) contents. The primary objective is to significantly enhance the microstructure and thermal–mechanical fatigue performance of the steel, thereby developing a high-performance, long-life hot working die steel designated as MES 2 steel. The thermal–mechanical fatigue (TMF) tests of two test steels were conducted in reverse mechanical strain control at 0.6% and 1.0% strain levels by a TMF servo-hydraulic testing system (MTS). The microstructures of the two steels were characterized using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results indicate that throughout the entire thermomechanical fatigue cycle, both steels exhibit initial hardening during the low-temperature half-cycle (tension half-cycle) and subsequent continuous softening during the high-temperature half-cycle (compression half-cycle). Furthermore, under the same strain condition, the cumulative cyclic softening damage of MES 1 steel is more pronounced than that of the newly developed MES 2 steel. The number, width, and length of cracks in MES 2 steel are smaller than those in MES 1 steel, and the thermomechanical fatigue life of MES 2 steel is significantly longer than that of MES 1 steel. The microstructures show that the main precipitate phase in MES 1 steel is Cr-dominated rod-shaped carbide. It presents obvious coarsening and is prone to inducing stress concentration, thus facilitating crack initiation and propagation. The precipitate phase in MES 2 steel is mainly MC carbide containing Mo and V. It has a high thermal activation energy and is dispersed in the matrix in the form of particles, pinning dislocations and grain boundaries. This effectively delays the reduction in dislocation density and grain growth, thus contributing positively to the improvement in thermomechanical fatigue performance. Full article
(This article belongs to the Special Issue Research on Performance Improvement of Advanced Alloys)
21 pages, 3245 KiB  
Article
Transition of CO2 from Emissions to Sequestration During Chemical Weathering of Ultramafic and Mafic Mine Tailings
by Xiaolin Zhang, Long-Fei Gou, Liang Tang, Shen Liu, Tim T. Werner, Feng Jiang, Yinger Deng and Amogh Mudbhatkal
Minerals 2025, 15(1), 68; https://doi.org/10.3390/min15010068 - 12 Jan 2025
Viewed by 449
Abstract
Weather-enhanced sulphide oxidation accelerates CO2 release into the atmosphere. However, over extended geological timescales, ultramafic and mafic magmatic minerals may transition from being sources of CO2 emissions to reservoirs for carbon sequestration. Ultramafic and mafic mine tailings present a unique opportunity [...] Read more.
Weather-enhanced sulphide oxidation accelerates CO2 release into the atmosphere. However, over extended geological timescales, ultramafic and mafic magmatic minerals may transition from being sources of CO2 emissions to reservoirs for carbon sequestration. Ultramafic and mafic mine tailings present a unique opportunity to monitor carbon balance processes, as mine waste undergoes instantaneous and rapid chemical weathering, which shortens the duration between CO2 release and absorption. In this study, we analysed 30 vanadium-titanium magnetite mine tailings ponds with varying closure times in the Panxi region of China, where ~60 years of mineral excavation and dressing have produced significant outcrops of mega-mine waste. Our analysis of anions, cations, saturation simulations, and 87Sr/86Sr; δ13C and δ34S isotopic fingerprints from mine tailings filtrates reveals that the dissolution load of mine tailings may depend significantly on early-stage sulphide oxidation. Despite the abundance of ultramafic and mafic minerals in tailings, dolomite dominates chemical weathering, accounting for ~79.2% of the cationic load. Additionally, due to sulphuric-carbonate weathering, the filtrates undergo deacidification along with sulphide depletion. The data in this study suggest that pristine V-Ti-Fe tailings ponds undergo CO2 emissions in the first two years but subsequently begin to absorb atmospheric CO2 along with the filtrates. Our results provide valuable insights into monitoring weathering transitions and carbon balance in ultramafic and mafic rocks. Full article
(This article belongs to the Special Issue CO2 Mineralization and Utilization)
14 pages, 1523 KiB  
Article
Microstructure, Hardness, and Wear Behavior of Layers Obtained by Electric Arc Hardfacing Processes
by Sebastian Balos, Danka Labus Zlatanović, Petar Janjatović, Milan Pećanac, Olivera Erić Cekić, Milena Rosić and Srećko Stopić
Materials 2025, 18(2), 299; https://doi.org/10.3390/ma18020299 - 10 Jan 2025
Viewed by 286
Abstract
Hardfacing is a welding-related technique aimed at depositing a harder and tougher layer onto a softer, less wear-resistant substrate or base metal. This process enhances the abrasion resistance of the component, increasing its durability under working conditions. A key feature of hardfacing is [...] Read more.
Hardfacing is a welding-related technique aimed at depositing a harder and tougher layer onto a softer, less wear-resistant substrate or base metal. This process enhances the abrasion resistance of the component, increasing its durability under working conditions. A key feature of hardfacing is dilution, which refers to the mixing of the hardfacing layer and the base metal. In this study, shielded metal arc welding (SMAW) was employed to hardface structural steel using chromium carbide vanadium consumables, with results compared to AISI D2 cold-work tool steel. Four different SMAW parameters were tested, and the abrasive test was conducted against SiC discs. Wear rate, represented by the wear loss rate, was correlated to microstructure, scanning electron microscopy, energy-dispersive X-ray spectroscopy, hardness, microhardness, and surface roughness. The results showed that key SMAW parameters, such as welding speed and current, significantly influence wear resistance. Specifically, slower welding speeds and higher currents, which result in greater heat input, led to the increased wear resistance of the deposited layer through the mechanism of the inoculation of larger and harder carbides. Full article
23 pages, 29777 KiB  
Article
Monitoring and Prevention Strategies for Iron and Aluminum Pollutants in Acid Mine Drainage (AMD): Evidence from Xiaomixi Stream in Qinling Mountains
by Xiaoya Wang, Min Yang, Huaqing Chen, Zongming Cai, Weishun Fu, Xin Zhang, Fangqiang Sun and Yangquan Li
Minerals 2025, 15(1), 59; https://doi.org/10.3390/min15010059 - 8 Jan 2025
Viewed by 430
Abstract
Acid mine drainage (AMD) generated during the exploitation and utilization of mineral resources poses a severe environmental problem globally within the mining industry. The Xiaomixi Stream in Ziyang County, Shaanxi Province, is a primary tributary of the Han River, which is surrounded by [...] Read more.
Acid mine drainage (AMD) generated during the exploitation and utilization of mineral resources poses a severe environmental problem globally within the mining industry. The Xiaomixi Stream in Ziyang County, Shaanxi Province, is a primary tributary of the Han River, which is surrounded by historically concentrated mining areas for stone coal and vanadium ores. Rainwater erosion of abandoned mine tunnels and waste rock piles has led to the leaching of acidic substances and heavy metals, which then enter the Haoping River and its tributaries through surface runoff. This results in acidic water, posing a significant threat to the water quality of the South-to-North Water Diversion Middle Route within the Han River basin. According to this study’s investigation, Xiaomixi’s acidic water exhibits yellow and white precipitates upstream and downstream of the river, respectively. These precipitates stem from the oxidation of iron-bearing minerals and aluminum-bearing minerals. The precipitation process is controlled by factors such as the pH and temperature, exhibiting seasonal variations. Taking the Xiaomixi Stream in Ziyang County, Shaanxi Province, as the study area, this paper conducts field investigations, systematic sampling of water bodies and river sediments, testing for iron and aluminum pollutants in water, and micro-area observations using field emission scanning electron microscopy (FESEM) on sediments, along with analyzing the iron and aluminum content. The deposition is analyzed using handheld X-ray fluorescence (XRF) analyzers, X-ray diffraction (XRD), and visible–near-infrared spectroscopy data, and a geochemical model is established using PHREEQC software. This paper summarizes the migration and transformation mechanisms of iron and aluminum pollutants in acidic water and proposes appropriate prevention and control measures. Full article
(This article belongs to the Special Issue Acid Mine Drainage: A Challenge or an Opportunity?)
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Figure 1

Figure 1
<p>Current status of mining operations and surface water pollution in the study area: (<b>a</b>) yellow precipitate upstream; and (<b>b</b>) white precipitate downstream.</p>
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<p>A geographical location map and substrate map of Xiaomixi.</p>
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<p>Distribution map of sampling points.</p>
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<p>Current status of mining operations and surface water pollution in the study area: (<b>a</b>) collect water samples; and (<b>b</b>) measure the pH of the water samples.</p>
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<p>Photos of the collected sediments: (<b>a</b>) upstream sediment samples; and (<b>b</b>) downstream sediment samples.</p>
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<p>Microscopic morphology of target minerals in the sample: (<b>a</b>) microscopic morphology diagram of upstream samples; and (<b>b</b>) microscopic morphology diagram of downstream samples.</p>
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<p>Secondary electron spectroscopy image of target minerals in the sample: (<b>a</b>) secondary electron spectrogram of upstream sample minerals; and (<b>b</b>) secondary electron spectroscopy image of downstream sample minerals.</p>
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<p>Variation map of the Fe mass percentage (wt%) in river sediments.</p>
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<p>Variation map of the Al mass percentage (wt%) in river sediments.</p>
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<p>The spectral curves of the samples: (<b>a</b>) the spectral curves of the samples numbered 1 to 8; and (<b>b</b>) the spectral curves of the samples numbered 9 to 13.</p>
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<p>XRD spectra of Fe and Al in sediment samples.</p>
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<p>Results of the Fe and Al ion content in the surface water experiments.</p>
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<p>Mass percentage of Fe and Al ions in the river sediments.</p>
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<p>Illustration of the sampling points for the tributaries.</p>
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57 pages, 17824 KiB  
Review
Eco-Friendly and Complex Processing of Vanadium-Bearing Waste for Effective Extraction of Valuable Metals and Other By-Products: A Critical Review
by Ahmed H. Ibrahim, Xianjun Lyu, Hani E. Sharafeldin and Amr B. ElDeeb
Recycling 2025, 10(1), 6; https://doi.org/10.3390/recycling10010006 - 5 Jan 2025
Viewed by 407
Abstract
Achieving the New World Sustainability Vision 2030 leads to enacting environmental restrictions, which aim to partially or totally reduce the negative impacts of different forms of waste and develop alternative technologies for eco-friendly and cost-effective utilization. Solid waste is a hazardous waste with [...] Read more.
Achieving the New World Sustainability Vision 2030 leads to enacting environmental restrictions, which aim to partially or totally reduce the negative impacts of different forms of waste and develop alternative technologies for eco-friendly and cost-effective utilization. Solid waste is a hazardous waste with many environmental and economic problems resulting from its storage and disposal. However, at the same time, these wastes contain many valuable elements. One of these solid wastes is heavy oil fly ash “HOFA” generated in power stations using heavy oil as fuel. HOFA is produced annually in massive amounts worldwide, the storage of which leads to the contamination of water resources by the contained heavy metals, resulting in many cancerogenic diseases. At the same time, these ashes contain many valuable metals in significant amounts, such as vanadium “V” and nickel “Ni” that can be extracted effectively compared to their low content and difficulty processing in their main ores. Hence, recycling these types of wastes reduces the environmental adverse effects of their storage and the harmful elements in their composition. This paper critically reviews the world resources of vanadium-bearing waste and various approaches described in the literature for recovering V, Ni, as well as other valuable metals from (HOFA) and other wastes, including pyro- and hydro-metallurgical processes or a combination. Hydro-metallurgical processes include alkaline or acidic leaching using different reagents followed by chemical precipitation, solvent extraction, and ion exchange to extract individual elements. The pyro-metallurgical processes involve the non-salt or salt roasting processes followed by acidic or alkaline leaching processes. The operational parameters and their impact on the efficiency of recovery are also discussed. The digestion mixtures of strong mineral acids used to dissolve metal ions in HOFA are also investigated. Bioleaching is a promising eco-friendly technology for recovering V and Ni through appropriate bacteria and fungi. Oxidation leaching is also a promising environmentally friendly approach and more effective. Among all these processes, the salt roasting treatment showed promising results concerning the cost, technological, and environmental effectiveness. The possibility of complex processing of HOFA has also been investigated, proposing innovative technology for completely utilizing this waste without any remaining residue. Effective zeolite for wastewater treatment has been formulated as a good alternative for conserving the available water resources. Full article
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Figure 1
<p>World mine production and global annual vanadium production and consumption [<a href="#B1-recycling-10-00006" class="html-bibr">1</a>,<a href="#B8-recycling-10-00006" class="html-bibr">8</a>].</p>
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<p>Overall flowchart showing the most common methods for the recovery of vanadium and nickel from industrial solid waste.</p>
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<p>Flowsheet of processing fly ash for recovering metal ions [<a href="#B58-recycling-10-00006" class="html-bibr">58</a>].</p>
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<p>The proposed technical flowsheet for the chemical treatment of El-kuriemat boiler ash [<a href="#B90-recycling-10-00006" class="html-bibr">90</a>].</p>
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<p>Flowchart of vanadium extraction from fly ash [<a href="#B101-recycling-10-00006" class="html-bibr">101</a>]. <sup>(S)</sup> Solid phase.</p>
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<p>Process flow chart for recovery of vanadium and nickel from fly ash [<a href="#B102-recycling-10-00006" class="html-bibr">102</a>].</p>
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<p>Two-stage leaching procedure to extract V, Mo, and Ni from fly ashes; (I) first stage alkaline leaching; (II) second stage acidic leaching [<a href="#B55-recycling-10-00006" class="html-bibr">55</a>]. <sup>(S)</sup> Solid phase.</p>
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<p>Schematic diagram of selective oxidation roasting of Fe<sub>2</sub>VO<sub>4</sub> [<a href="#B131-recycling-10-00006" class="html-bibr">131</a>].</p>
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<p>Novel process for extracting low valence vanadium from vanadium slag [<a href="#B110-recycling-10-00006" class="html-bibr">110</a>].</p>
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<p>The block diagram for the carbonaceous fly ash combustion followed by acid leaching and oxidative precipitation of vanadium as V<sub>2</sub>O<sub>5</sub> [<a href="#B56-recycling-10-00006" class="html-bibr">56</a>].</p>
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<p>Flowsheet of vanadium extraction from vanadium slag using the non-salt roasting method [<a href="#B109-recycling-10-00006" class="html-bibr">109</a>].</p>
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<p>Flowchart of vanadium recovery from slag using calcification roasting-acid leaching technique [<a href="#B137-recycling-10-00006" class="html-bibr">137</a>].</p>
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<p>Flowsheet for the recovery of vanadium from vanadium slag by calcification roasting-two step leaching process [<a href="#B142-recycling-10-00006" class="html-bibr">142</a>].</p>
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<p>Flowsheet of ammonium carbonate leaching of vanadium slag [<a href="#B143-recycling-10-00006" class="html-bibr">143</a>].</p>
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<p>Novel process based on salt-roasting to extract vanadium and chromium from the V-Cr slag [<a href="#B43-recycling-10-00006" class="html-bibr">43</a>].</p>
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<p>Schematic flow of salt-roasting and water-leaching process from boiler ash for vanadium extraction [<a href="#B59-recycling-10-00006" class="html-bibr">59</a>].</p>
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<p>The quantitative flowsheet for V recovery from Egyptian boiler ash using sodium salt-roasting and water-leaching process [<a href="#B59-recycling-10-00006" class="html-bibr">59</a>].</p>
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<p>SEM images of roasted boiler ash sample: (<b>a</b>) at 700 °C for 2 h, and (<b>b</b>) elemental mapping images of burned surface.</p>
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<p>Line scan and distribution elements of the roasted boiler ash at 700 °C.</p>
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<p>SEM images of roasted boiler ash sample: (<b>a</b>) at 850 °C for 2 h, (<b>b</b>) elemental mapping images of the surface, and (<b>c</b>) back-scattered morphology image [<a href="#B59-recycling-10-00006" class="html-bibr">59</a>].</p>
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<p>Line scan and distribution elements of the roasted boiler ash at 850 °C.</p>
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<p>SEM images of roasted boiler ash sample: (<b>a</b>) at 1000 °C for 2 h, (<b>b</b>) elemental mapping images of the polished surface, and (<b>c</b>) back-scattered morphology image.</p>
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<p>The quantitative scheme for the recovery of Ni, Zn, and other by-products from water leaching solid residue obtained from the salt roasting of Egyptian boiler ash.</p>
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<p>Diagram of the different procedures for synthesizing zeolite from fly ash [<a href="#B215-recycling-10-00006" class="html-bibr">215</a>].</p>
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<p>Schematic procedures of synthesized zeolite based on Egyptian boiler ash residues [<a href="#B219-recycling-10-00006" class="html-bibr">219</a>].</p>
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<p>XRD Patterns of synthesized zeolite produced from mixture of SASR-Kaolin at weight ratios of (a) 1:0, (b) 1:2, (c) 1:1.5, (d) 1:1, (e) 2:1, and (f) 0:1. (<b>A</b>) XRD Patterns of synthesized products with different mass ratio of mixture-NaOH of 1:1.3 and 1:2. (<b>B</b>) where ●: Faujasite, and ∆: Sodalite zeolite [<a href="#B219-recycling-10-00006" class="html-bibr">219</a>].</p>
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<p>The proposed adsorption mechanism of heavy metal ions on synthesized zeolite.</p>
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40 pages, 9273 KiB  
Review
Revisiting Intercalation Anode Materials for Potassium-Ion Batteries
by María José Piernas-Muñoz and Maider Zarrabeitia
Materials 2025, 18(1), 190; https://doi.org/10.3390/ma18010190 - 4 Jan 2025
Viewed by 748
Abstract
Potassium-ion batteries (KIBs) have attracted significant attention in recent years as a result of the urgent necessity to develop sustainable, low-cost batteries based on non-critical raw materials that are competitive with market-available lithium-ion batteries. KIBs are excellent candidates, as they offer the possibility [...] Read more.
Potassium-ion batteries (KIBs) have attracted significant attention in recent years as a result of the urgent necessity to develop sustainable, low-cost batteries based on non-critical raw materials that are competitive with market-available lithium-ion batteries. KIBs are excellent candidates, as they offer the possibility of providing high power and energy densities due to their faster K+ diffusion and very close reduction potential compared with Li+/Li. However, research on KIBs is still in its infancy, and hence, more investigation is required both at the materials level and at the device level. In this work, we focus on recent strategies to enhance the electrochemical properties of intercalation anode materials, i.e., carbon-, titanium-, and vanadium-based compounds. Hitherto, the most promising anode materials are those carbon-based, such as graphite, soft, or hard carbon, each with its advantages and disadvantages. Although a wide variety of strategies have been reported with excellent results, there is still a need to improve the standardization of the best carbon properties, electrode formulation, and electrolyte composition, given the impossibility of a direct comparison. Therefore, additional effort should be made to understand what are the crucial carbon parameters to develop a reference electrode and electrolyte formulation to further boost their performance and move a step forward in the commercialization of KIBs. Full article
(This article belongs to the Special Issue Advanced Anode Materials for Alkali-Ion Batteries)
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Figure 1

Figure 1
<p>An overview of the intercalation anode materials under investigation for KIBs addressed in this review.</p>
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<p>(<b>a</b>) AB stacked graphite structure, where the C-C distance (1.42 Å) in the hexagonal close packing within a graphene layer and the interplanar distance between graphene layers (3.35 Å) are observed. (<b>b</b>) Schematic top view of the AB layer stacking structure of graphite (figures adapted from Josef Sivek [<a href="#B40-materials-18-00190" class="html-bibr">40</a>]). (<b>c</b>) Graphene monolayer.</p>
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<p>(<b>a</b>) Potential of the K-GICs vs. “x” in K<sub>x</sub>C<sub>8</sub> (experimental results are plotted in black and DFT calculations in red). (<b>b</b>) Stage transition model for K-GICs. Step I: K<sup>+</sup> intercalation, Step II: interstage intercalation (stage 3–stage 2), Step III: intra-stage intercalation (stage 2–stage 2′), and Step IV: interstage intercalation (stage 2–stage 1). Reproduced with permission from [<a href="#B45-materials-18-00190" class="html-bibr">45</a>].</p>
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<p>Advantages and disadvantages of graphite in KIBs and possible solutions to the latter.</p>
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<p>Influence of the (<b>a</b>) binder: PVDF, PANa, and CMCNa (figures adapted from Shinichi Komaba [<a href="#B31-materials-18-00190" class="html-bibr">31</a>]), and electrolyte: (<b>b</b>) 1 M KPF<sub>6</sub> in EC:PC (adapted from Jin Zhao [<a href="#B44-materials-18-00190" class="html-bibr">44</a>]), (<b>c</b>) 1 M KPF<sub>6</sub> in glyme (figure adapted from Adam P. Cohn [<a href="#B54-materials-18-00190" class="html-bibr">54</a>]), (<b>d</b>) 0.7 M KFSI in glyme (adapted from Tomooki Hosaka [<a href="#B59-materials-18-00190" class="html-bibr">59</a>]), (<b>e</b>) 2 M KFSI in TEP (figure adapted from Sailin Liu [<a href="#B64-materials-18-00190" class="html-bibr">64</a>]), (<b>f</b>) 2 M KFSI in TMP and 6 wt.% DTD (adapted from Gang Liu [<a href="#B70-materials-18-00190" class="html-bibr">70</a>]), and (<b>g</b>) 2 M KFSI in EC: DEC with 2 wt.% DTD and 0.5 wt.% CAPE (figure adapted from Mingyuan Gu [<a href="#B71-materials-18-00190" class="html-bibr">71</a>]) on the voltage profile of graphite.</p>
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<p>Structures of (<b>a</b>) T-graphene-like BC<sub>2</sub>N (reproduced from ref. [<a href="#B104-materials-18-00190" class="html-bibr">104</a>]), (<b>b</b>) twin graphene (reproduced from ref. [<a href="#B107-materials-18-00190" class="html-bibr">107</a>]), and (<b>c</b>) 2D TOD-graphene (reproduced with permission from ref. [<a href="#B106-materials-18-00190" class="html-bibr">106</a>]). In T-graphene-like BC<sub>2</sub>N, purple balls represent the possible absorption sites of K. In TOD-graphene, top (upper image) and side views (bottom image) are shown, where blue and pink balls depict atoms from the graphene lattice and the kagome lattice, respectively.</p>
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<p>Schematic illustrations of the structure of (<b>a</b>) graphite, (<b>b</b>) soft (disordered, graphitizable) carbon, and (<b>c</b>) hard (disordered, non-graphitizable) carbon.</p>
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<p>Voltage profiles and cycling performance of HC anode materials doped with (<b>a</b>,<b>b</b>) N (adapted from C. Chen [<a href="#B120-materials-18-00190" class="html-bibr">120</a>]), (<b>c</b>,<b>d</b>) P (adapted from S. Alvin [<a href="#B122-materials-18-00190" class="html-bibr">122</a>]), (<b>e</b>,<b>f</b>) S (adapted from Y. Zhang [<a href="#B123-materials-18-00190" class="html-bibr">123</a>]), (<b>g</b>,<b>h</b>) N/O (adapted from J. Yang [<a href="#B124-materials-18-00190" class="html-bibr">124</a>]), (<b>i</b>,<b>j</b>) S/O (adapted from M. Chen [<a href="#B125-materials-18-00190" class="html-bibr">125</a>]), and (<b>k</b>,<b>l</b>) N/S (adapted from Y. Liu [<a href="#B126-materials-18-00190" class="html-bibr">126</a>]), respectively. The electrolyte used and the current density applied are detailed in the cyclability graphs.</p>
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<p>Typical structure of a (<b>a</b>) CNT (credit image: Mrs. Plugiano [<a href="#B128-materials-18-00190" class="html-bibr">128</a>]), (<b>b</b>) CNC (adapted with permission from ref. [<a href="#B129-materials-18-00190" class="html-bibr">129</a>]), and (<b>c</b>) CNS (reproduced with permission from ref. [<a href="#B130-materials-18-00190" class="html-bibr">130</a>]).</p>
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<p>C-rate capabilities and long-term cyclabilities of (<b>a</b>,<b>b</b>) TiO<sub>2</sub>-coated layered titanate with polyaniline intercalated, HTO-PANI-600 (reproduced with permission from J. Liao [<a href="#B151-materials-18-00190" class="html-bibr">151</a>]), (<b>c</b>,<b>d</b>) TiO<sub>2</sub>@NGC (reproduced with permission from J. P. Dubal [<a href="#B153-materials-18-00190" class="html-bibr">153</a>]), and (<b>e</b>,<b>f</b>) Mn<sub>0.5</sub>Ti<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub>@C (reproduced with permission from S. Liu [<a href="#B164-materials-18-00190" class="html-bibr">164</a>]).</p>
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<p>C-rate capabilities and long-term cyclabilities of (<b>a</b>,<b>b</b>) C@V<sub>2</sub>O<sub>5</sub>@CNFs (reproduced with permission from X. Xiang [<a href="#B171-materials-18-00190" class="html-bibr">171</a>]), (<b>c</b>,<b>d</b>) VO@C (reproduced with permission from J. Lu [<a href="#B172-materials-18-00190" class="html-bibr">172</a>]), and (<b>e</b>,<b>f</b>) V<sub>2</sub>O<sub>3</sub>@C (reproduced with permission from J. Hu [<a href="#B178-materials-18-00190" class="html-bibr">178</a>]).</p>
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<p>Comparison of (<b>a</b>) ICE and (<b>b</b>) capacities of graphite after 50–100 cycles* using different combinations of graphite (red), binders (green), and electrolytes (blue). Values gathered from <a href="#materials-18-00190-t002" class="html-table">Table 2</a>. * The capacity of graphite: PVDF and graphite: CMC electrodes tested in 1 M KFSI in EC: DEC corresponds to a cyclability of only 20 and 8 cycles, respectively.</p>
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<p>Comparison of (<b>a</b>) ICE and (<b>b</b>) capacities of SC or HC achieved after 50–100 cycles using different active material (red).</p>
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14 pages, 5412 KiB  
Article
Temperature-Independent Thermal Radiation Design Using Phase-Change Materials
by Viktoriia E. Babicheva, Heungsoo Kim and Alberto Piqué
Coatings 2025, 15(1), 38; https://doi.org/10.3390/coatings15010038 - 2 Jan 2025
Viewed by 468
Abstract
The ability to treat the surface of an object with coatings that counteract the change in radiance resulting from the object’s blackbody emission can be very useful for applications requiring temperature-independent radiance behavior. Such a response is difficult to achieve with most materials [...] Read more.
The ability to treat the surface of an object with coatings that counteract the change in radiance resulting from the object’s blackbody emission can be very useful for applications requiring temperature-independent radiance behavior. Such a response is difficult to achieve with most materials except when using phase-change materials, which can undergo a drastic change in their optical response, nullifying the changes in blackbody radiation across a narrow range of temperatures. We report on the theoretical design, giving the possibility of extending the temperature range for temperature-independent radiance coatings by utilizing multiple layers, each comprising a different phase-change material. These designed multilayer coatings are based on thin films of samarium nickelate, vanadium dioxide, and doped vanadium oxide and cover temperatures ranging from room temperature to up to 140 °C. The coatings are numerically engineered in terms of layer thickness and doping, with each successive layer comprising a phase-change material with progressively higher transition temperatures than those below. Our calculations demonstrate that the optimized thin film multilayers exhibit a negligible change in the apparent temperature of the engineered surface. These engineered multilayer films can be used to mask an object’s thermal radiation emission against thermal imaging systems. Full article
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<p>(<b>a</b>) Schematic illustrating the thermal concealment of a hot surface. The unconcealed surface appears to have different temperatures upon heating. In contrast, the ideal concealed surface appears to have the same temperature with low radiance, even when the actual temperature of the surface is increased. (<b>b</b>) Spectral radiances of a SiO<sub>2</sub> substrate for different temperatures (35, 70, 100, and 140 °C). The plot shows typical unconcealed thermal changes determined primarily by changes in blackbody radiation.</p>
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<p>Effect of one layer of phase-change material on emitted radiance. (<b>a</b>,<b>b</b>) SmNiO<sub>3</sub> and (<b>c</b>,<b>d</b>) VO<sub>2</sub> on AZO/SiO<sub>2</sub>. (<b>a</b>) SmNiO<sub>3</sub> minimizes FoM in the temperature range of 100–140 °C, which corresponds to its phase transition, and the ideal thickness of SmNiO<sub>3</sub> is &gt;200 nm, denoted by a red circle. (<b>b</b>) Spectral emissivity of the coating with 200-nm SmNiO<sub>3</sub>. (<b>c</b>) VO<sub>2</sub> strongly affects the radiance at temperatures around 45–70 °C, and the ideal thickness of VO<sub>2</sub> is approximately 450 nm, indicated by a red circle. (<b>d</b>) Spectral emissivity of the coating with 450-nm VO<sub>2</sub>.</p>
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<p>FoM for a combination of SmNiO<sub>3</sub> and VO<sub>2</sub> layers. The combination of layers extends the operating temperature range of the operation. Variations in the thickness of (<b>a</b>) VO<sub>2</sub> and (<b>b</b>) SmNiO<sub>3</sub>. In both cases, the optimal thickness is approximately 200 nm (denoted red circles).</p>
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<p>Further extension of the temperature range achieved with W doping of VO<sub>2</sub>. (<b>a</b>) FoM for three layers of materials, SmNiO<sub>3</sub>, VO<sub>2</sub>, and W:VO<sub>2</sub> (0.93 at. %), changing the phase at different temperatures. The red circle shows the optimal range of SmNiO<sub>3</sub> thickness. (<b>b</b>) Comparison of FoMs for the best coating in each category. SmNiO<sub>3</sub> works only in one band (100–135 °C). Adding layers of VO<sub>2</sub> extends the effect to lower temperatures (35–70 °C). (<b>c</b>,<b>d</b>) Spectral radiances for the lower and higher temperature bands, respectively. The comparison is shown for engineered coating (SmNiO<sub>3</sub>, VO<sub>2</sub>, and 0.93 at. % W:VO<sub>2</sub>, solid lines) and bare SiO<sub>2</sub> substrate (dotted lines). The wavelength range is approximately divided into two ranges, and the range of 10–14 μm shows a much better performance of thermal emission management than 8–10 μm.</p>
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<p>(<b>a</b>,<b>b</b>) Performance of the engineered emitter (SmNiO<sub>3</sub>, VO<sub>2</sub>, and 0.93 at. % W:VO<sub>2</sub>) in different wavelength ranges of operation: (<b>a</b>) range 8–10 μm and (<b>b</b>) range 10–14 μm. Thermal coating is better if detection is performed only in the long-wave infrared range. The red circles in (<b>a</b>,<b>b</b>) show the optimal range of SmNiO<sub>3</sub> thickness. (<b>c</b>,<b>d</b>) Spectral emissivity of multilayer coatings: (<b>c</b>) VO<sub>2</sub> and SmNiO<sub>3</sub> combination is shown for each layer of 200 nm, and (<b>d</b>) bilayer of VO<sub>2</sub> with SmNiO<sub>3</sub> is for 150-nm VO<sub>2</sub>, 200-nm W:VO<sub>2</sub>, and 200-nm SmNiO<sub>3</sub>.</p>
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<p>Comparison of the spectral radiance of unconcealed and concealed surfaces. (<b>a</b>) Calculations for the SiO<sub>2</sub> substrate and (<b>b</b>) for the optimized engineered emitter consisting of three layers of materials, SmNiO<sub>3</sub>, VO<sub>2</sub>, and W:VO<sub>2</sub> (0.93 at. %), on top of the AZO/SiO<sub>2</sub> substrate. Both maps are presented with the same color bar to show the relative performance of the thermal coating.</p>
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<p>Multilayer engineered coatings that potentially cover the full range of temperatures, that is, from 35 °C to 135 °C: (<b>a</b>) design involving VO<sub>2</sub> doped with low-valence metal ions and (<b>b</b>) design involving epitaxial superlattices of SmNiO<sub>3</sub> and NdNiO<sub>3</sub>.</p>
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15 pages, 2623 KiB  
Article
Impact of Vanadium and Zirconium Contents on Properties of Novel Lightweight Ti3ZryNbVx Refractory High-Entropy Alloys
by Noura Al-Zoubi, Amer Almahmoud and Abdalla Obeidat
Solids 2025, 6(1), 2; https://doi.org/10.3390/solids6010002 - 2 Jan 2025
Viewed by 407
Abstract
This research explores the physical properties of refractory high-entropy alloys Ti3ZryNbVx (0.5 ≤ x ≤ 3.5; 1 ≤ y ≤ 2), utilizing the first-principles exact muffin-tin orbitals method, in addition to the coherent potential approximation. We examine the [...] Read more.
This research explores the physical properties of refractory high-entropy alloys Ti3ZryNbVx (0.5 ≤ x ≤ 3.5; 1 ≤ y ≤ 2), utilizing the first-principles exact muffin-tin orbitals method, in addition to the coherent potential approximation. We examine the atomic size difference (δ), the valence electron concentration (VEC) and the total energy of the body-centered cubic (bcc), the face-centered cubic (fcc) and the hexagonal close-packed (hcp) lattices, revealing a disordered solid solution with a bcc lattice as the stable phase of these alloys. The stability of the bcc Ti3ZryNbVx alloys increases with the addition of vanadium, and slightly decreases with increasing Zr concentration. All the investigated RHEAs have densities less than 6.2 g/cm3. Adding V to the Ti-Zr-Nb-V system reduces the volume and slightly enhances the density of the studied alloys. Our results show that increasing V content increases the tetragonal shear modulus C′, which assures that V enhances the mechanical stability of the bcc phase, and also increases the elastic moduli. Moreover, all the examined alloys are ductile. Vickers hardness and bond strength increase as V concentration increases. In contrast, decreasing Zr content reduces the density and increases the hardness and the bond strength of the present RHEAs, potentially resulting in systems with desirable mechanical properties and lower densities. These findings provide theoretical insights into the behavior of RHEAs, and emphasize the necessity for additional experimental investigations. Full article
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<p>The energy differences between the hcp and bcc phases (<b>left panel</b>) and between the fcc and bcc phases (<b>right panel</b>) of Ti<sub>3</sub>ZrNbV<span class="html-italic"><sub>x</sub></span><sub>,</sub> Ti<sub>3</sub>Zr<sub>1.5</sub>NbV<span class="html-italic"><sub>x</sub></span> and Ti<sub>3</sub>Zr<sub>2</sub>NbV<span class="html-italic"><sub>x</sub></span> RHEAs, as a function of V content (<span class="html-italic">x</span>).</p>
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<p>The right panel is the calculated Wigner–Seitz radius (in Bohr) and the left panel is the volumetric density (in g/cm<sup>3</sup>) of the Ti<sub>3</sub>ZrNbV<span class="html-italic"><sub>x</sub></span>, Ti<sub>3</sub>Zr<sub>1.5</sub>NbV<span class="html-italic"><sub>x</sub></span> and Ti<sub>3</sub>Zr<sub>2</sub>NbV<span class="html-italic"><sub>x</sub></span> RHEAs as a function of V content (<span class="html-italic">x</span>).</p>
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<p>The calculated single-crystal elastic constants <span class="html-italic">C</span><sub>11</sub>, <span class="html-italic">C</span><sub>12</sub>, <span class="html-italic">C</span>’ and <span class="html-italic">C</span><sub>44</sub> (units of GPa) for the bcc Ti<sub>3</sub>ZrNbV<span class="html-italic"><sub>x</sub></span>, Ti<sub>3</sub>Zr<sub>1.5</sub>NbV<span class="html-italic"><sub>x</sub></span> and Ti<sub>3</sub>Zr<sub>2</sub>NbV<span class="html-italic"><sub>x</sub></span> as a function of V atomic fraction <span class="html-italic">x</span>.</p>
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<p>The theoretical elastic moduli <span class="html-italic">B</span>, <span class="html-italic">G</span>, <span class="html-italic">E</span> and the <span class="html-italic">B</span>/<span class="html-italic">G</span> ratio for the bcc Ti<sub>3</sub>ZrNbV<span class="html-italic"><sub>x</sub></span>, Ti<sub>3</sub>Zr<sub>1.5</sub>NbV<span class="html-italic"><sub>x</sub></span> and Ti<sub>3</sub>Zr<sub>2</sub>NbV<span class="html-italic"><sub>x</sub></span>, versus V content (<span class="html-italic">x</span>).</p>
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<p>The calculated Poisson’s ratio <span class="html-italic">ν</span>(<span class="html-italic">x</span>) and Vickers hardness in the bcc phase for the Ti<sub>3</sub>ZrNbV<span class="html-italic"><sub>x</sub></span>, Ti<sub>3</sub>Zr<sub>1.5</sub>NbV<span class="html-italic"><sub>x</sub></span> and Ti<sub>3</sub>Zr<sub>2</sub>NbV<span class="html-italic"><sub>x</sub></span> RHEAs, versus V content (<span class="html-italic">x</span>).</p>
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<p>The calculated total density of states (TDOS) for the bcc Ti<sub>3</sub>ZrNbV<span class="html-italic"><sub>x</sub></span>, Ti<sub>3</sub>Zr<sub>1.5</sub>NbV<span class="html-italic"><sub>x</sub></span> and Ti<sub>3</sub>Zr<sub>2</sub>NbV<span class="html-italic"><sub>x</sub></span> RHEAs with different values of V content <span class="html-italic">x</span> (<span class="html-italic">x</span> = 0.5, 2, and 3.5). Vertical dashed lines indicate the Fermi energies at 0 Ry.</p>
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16 pages, 4595 KiB  
Article
Timing and Nature of Gemstone Tsavorite from Kenya: Constraints from In Situ U-Pb LA-ICP-MS Dating
by Shiqi Wang, Nai Wang, Siyi Zhao and Sen Wang
Minerals 2025, 15(1), 46; https://doi.org/10.3390/min15010046 - 1 Jan 2025
Viewed by 407
Abstract
Gem-quality green vanadium grossular (var. tsavorite) is exclusively hosted in the Neoproterozoic Metamorphic Mozambique Belt (NMMB). The geochronology of tsavorite is limited until now, and the accurate crystallization age of the tsavorite in Kenya has remained unknown. Based on conventional gemological analyzing, by [...] Read more.
Gem-quality green vanadium grossular (var. tsavorite) is exclusively hosted in the Neoproterozoic Metamorphic Mozambique Belt (NMMB). The geochronology of tsavorite is limited until now, and the accurate crystallization age of the tsavorite in Kenya has remained unknown. Based on conventional gemological analyzing, by means of modern testing methods such as gemological analysis, UV-visible spectroscopy, Infrared spectroscopy, Raman spectroscopy, Electron probe, the spectral characteristics and chemical composition of tsavorite were determined, aiming to investigate the coloring elements of green garnets and trace the origin of tsavorite samples. The UV-Vis-NIR spectra and chemical composition analysis results show that vanadium and chromium are the main coloring elements in green tsavorite from Kenya. Combining the values of the δ18O (14.11‰) with the V/Cr ratio (around 4.4) of the tsavorite samples, the accuracy of the sample source has been identified. U–Pb dating of tsavorite from Kenya provides a concordant U-Pb age of 626.3 ± 4.6 Ma, in agreement with the weighted mean 206Pb /238U age of 625.9 ± 4.7 Ma (MSWD = 0.36), which indicated that Kenyan tsavorites were generated during the East African orogeny. Application of in situ laser U-Pb geochronology on gem-quality tsavorite to determine the mineralization time of Neoproterozoic Metamorphic Mozambique Belt of Kenya, which is the first step in characterizing the in situ dating analysis of gemstone tsavorite in Kenya mineral deposits Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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<p>Schematic geological map of the Neoproterozoic Metamorphic Mozambique Belt in south-eastern Kenya and location of the Kenyan tsavorite deposits. (modified from [<a href="#B1-minerals-15-00046" class="html-bibr">1</a>,<a href="#B4-minerals-15-00046" class="html-bibr">4</a>,<a href="#B12-minerals-15-00046" class="html-bibr">12</a>,<a href="#B13-minerals-15-00046" class="html-bibr">13</a>]).</p>
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<p>The 8 faceted tsavorite samples.</p>
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<p>Internal features of the tsavorites; (<b>A</b>,<b>B</b>) Black solid inclusions identified as graphite by Raman test; (<b>C</b>) Fine parallel growth tubes inclusions; (<b>D</b>) Solid crystal inclusion and two-phase inclusion; (<b>E</b>) Dense fingerprint like inclusions; (<b>F</b>) Rich fern leaf like gas-liquid inclusions.</p>
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<p>The representative UV–vis–NIR spectra of the tsavorites.</p>
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<p>Representative Infrared Spectrum of the tsavorites.</p>
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<p>Representative Raman Spectrum of the tsavorites.</p>
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<p>Chondrite-normalized REE patterns of the different parts of tsavorite (the normalization values for chondrite were from [<a href="#B31-minerals-15-00046" class="html-bibr">31</a>]).</p>
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<p>(<b>A</b>) The concordant U-Pb age of tsavorite samples; (<b>B</b>) The weighted mean <sup>206</sup>Pb /<sup>238</sup>U age of tsavorite samples. MSWD: mean square of weighted deviates.</p>
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<p>Ternary diagram goldmanite-grossular-uvarovite displaying the end-member compositions of tsavorite samples from Kenya and those from other origins (the data for other origins are sourced from the literature [<a href="#B35-minerals-15-00046" class="html-bibr">35</a>]).</p>
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<p>(<b>A</b>) V/Cr ratio chart of tsavorite samples; (<b>B</b>) Origin traceability map combining V/Cr ratio and δ<sup>18</sup>O value (the data for other origins are sourced from the literature [<a href="#B32-minerals-15-00046" class="html-bibr">32</a>]).</p>
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27 pages, 3932 KiB  
Article
Evaluation of the Anti-Amyloid and Anti-Inflammatory Properties of a Novel Vanadium(IV)–Curcumin Complex in Lipopolysaccharides-Stimulated Primary Rat Neuron-Microglia Mixed Cultures
by Georgios Katsipis, Sophia N. Lavrentiadou, George D. Geromichalos, Maria P. Tsantarliotou, Eleftherios Halevas, George Litsardakis and Anastasia A. Pantazaki
Int. J. Mol. Sci. 2025, 26(1), 282; https://doi.org/10.3390/ijms26010282 - 31 Dec 2024
Viewed by 393
Abstract
Lipopolysaccharides (LPS) are bacterial mediators of neuroinflammation that have been detected in close association with pathological protein aggregations of Alzheimer’s disease. LPS induce the release of cytokines by microglia and mediate the upregulation of inducible nitric oxide synthase (iNOS)—a mechanism also associated with [...] Read more.
Lipopolysaccharides (LPS) are bacterial mediators of neuroinflammation that have been detected in close association with pathological protein aggregations of Alzheimer’s disease. LPS induce the release of cytokines by microglia and mediate the upregulation of inducible nitric oxide synthase (iNOS)—a mechanism also associated with amyloidosis. Curcumin is a recognized natural medicine but has extremely low bioavailability. V-Cur, a novel hemocompatible Vanadium(IV)-curcumin complex with higher solubility and bioactivity than curcumin, is studied here. Co-cultures consisting of rat primary neurons and microglia were treated with LPS and/or curcumin or V-Cur. V-Cur disrupted LPS-induced overexpression of amyloid precursor protein (APP) and the in vitro aggregation of human insulin (HI), more effectively than curcumin. Cell stimulation with LPS also increased full-length, inactive, and total iNOS levels, and the inflammation markers IL-1β and TNF-α. Both curcumin and V-Cur alleviated these effects, with V-Cur reducing iNOS levels more than curcumin. Complementary insights into possible bioactivity mechanisms of both curcumin and V-Cur were provided by In silico molecular docking calculations on Aβ1-42, APP, Aβ fibrils, HI, and iNOS. This study renders curcumin-based compounds a promising anti-inflammatory intervention that may be proven a strong tool in the effort to mitigate neurodegenerative disease pathology and neuroinflammatory conditions. Full article
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Graphical abstract
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<p>Levels of amyloid precursor protein (APP) in mixed cultures of primary neuron-microglia, in the absence or presence of 0.1, 1, or 10 μg/mL of LPS (<b>a</b>,<b>b</b>). Effect of LPS (1 μg/mL) in the presence or absence of 2 μΜ curcumin or V-Cur complex on APP levels (<b>c</b>,<b>d</b>). Analysis performed with Western blotting. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used to verify equal loading. The density of the blots was semi-quantified with ImageJ 1.54. Results are presented as fractional changes in comparison with the control sample and are the mean (±SD) of three independent biological experiments. One-way ANOVA was employed to compare untreated or LPS-treated samples. Statistical significance when compared with: * untreated sample (control); # LPS-treated sample; <span>$</span> curcumin-treated: * <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001; **** <span class="html-italic">p</span> &lt; 0.0001; #### <span class="html-italic">p</span> &lt; 0.0001; <span>$</span><span>$</span><span>$</span><span>$</span> <span class="html-italic">p</span> &lt; 0.0001.</p>
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<p>Docking poses orientation of curcumin and V-Cur in the crystal structure of the Kunitz protease inhibitor domain (APPI) of APP (PDB accession number 1AAP). The target protein is illustrated as a semi-transparent cartoon and surface colored in yellow orange and chocolate (chains A and B, respectively), while curcumin and V-Cur molecules are rendered in ball-and-stick mode and colored according to atom type in light pink and violet purple C atoms, respectively. The ligand binding site of both molecules depicting the architecture of the binding interactions is also illustrated (in the upper part) with an additional depiction of selected contacting amino acid residues of the binding pocket rendered in line and colored according to the cartoon. Binding interactions are illustrated in light pink (for curcumin) and violet (for V-Cur). Heteroatom color code: V: grey, N: blue, and O: red. Molecular docking simulations of both ligands were performed individually. Hydrogen atoms are omitted for clarity. The final structure was ray-traced and illustrated with the aid of PyMol Molecular Graphics.</p>
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<p>In vitro fibrillation assay with insulin in the presence of several concentrations (0–100 μΜ) of either curcumin (■) or V-Cur (●). The insulin amyloid fibers formed in the absence or presence of either curcumin or V-Cur were semi-quantified by employing Thioflavin T fluorescence, with excitation at 450 nm and recording the emission spectrum at 490 nm. The results from three independent experiments are provided as mean normalized fibrillization rates (±SEM), setting the value of the control sample as 100%. Some error bars are not visible due to very small values (&lt;1%).</p>
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<p>Docking pose orientation of curcumin and V-Cur in the crystal structure of dimer (PDB ID 1GUJ) and hexamer (PDB ID 6GNQ) HΙ target proteins. In the hexameric structure of HI are also illustrated the six chain-stabilizing Zn<sup>2+</sup> ions, the co-crystallized meta-cresol (CRS, depicted in gold sticks), and some critical to self-assembly and aggregation resides of HI (represented in stick mode colored in orange). Both HI proteins’ structures are depicted as cartoon colored in wheat and firebrick for A and B chains, respectively. Curcumin and V-Cur are rendered in sphere representation colored according to atom type in light pink and violet purple, respectively. The two Zn ions co-crystallized in the hexameric structure are depicted in sphere representation in lemon color and are shown to be connected with polar contact with Nε2 of His10 in the three double chains (A and B). Heteroatom color code: V: grey, N: blue, and O: red. Molecular docking simulations of both ligands were performed individually. Hydrogen atoms are omitted for clarity. The final structure was ray-traced and illustrated with the aid of PyMol Molecular Graphics.</p>
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<p>Levels of (<b>a</b>) active inducible NO synthase (iNOS) (100 kDa), (<b>b</b>) inactive iNOS (50 and 75 kDa), and (<b>c</b>) total iNOS levels, after 24 h of treatment with LPS 1 μg/mL, in the presence or absence of 2 μΜ of curcumin or V-Cur complex, in mixed cultures of primary neurons-microglia. iNOS levels were determined by Western blotting (<b>d</b>). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was employed to verify equal loading. The density of the blots was semi-quantified with ImageJ 1.54. Results are presented as fractional changes in comparison with the control sample and are the mean (±SD) of three independent biological experiments. One-way ANOVA was employed to compare untreated or LPS-treated samples. Statistical significance when compared with: * untreated sample (control); # LPS-treated sample; <span>$</span> curcumin-treated: * <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001; **** <span class="html-italic">p</span> &lt; 0.0001; # <span class="html-italic">p</span> &lt; 0.05; ## <span class="html-italic">p</span> &lt; 0.01; ### <span class="html-italic">p</span> &lt; 0.001; #### <span class="html-italic">p</span> &lt; 0.0001; <span>$</span> <span class="html-italic">p</span> &lt; 0.05; <span>$</span><span>$</span> <span class="html-italic">p</span> &lt; 0.01.</p>
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<p>Docking pose orientation of curcumin and V-Cur in the crystal structure of iNOS monomer enzyme (PDB accession number 4NOS). The target protein is illustrated as cartoon colored in the sand along with a semi-transparent surface colored in the dark sand. Curcumin and V-Cur molecules, as well as the co-crystallized iNOS inhibitor ethylisothiourea (ITU) are rendered in sphere mode and colored according to atom type in light pink, violet purple, and hot pink C atoms, respectively. The co-crystallized molecules heme (HEM) (iron protoporphyrin IX) and H2B superimposed with the docked molecules are rendered in stick representation and colored according to atom type in orange and yellow-orange C atoms, respectively. H4B, essential for the dimerization of the protein, is not shown since it is located farther down the binding cavity, near the dimerization interface. The target protein structure model in the lower panel, depicting in a close-up view of the binding cavity of the target enzyme the architecture of the binding interactions, is illustrated as a semi-transparent surface colored in dark sand with an additional depiction of selected contacting amino acid residues of the binding pocket highlighted in the molecular surface in smudge green (for V-Cur) and white (for curcumin). Binding interaction residues are labeled in white (for curcumin) and smudge green (for V-Cur). Heteroatom color code: V: grey, N: blue, and O: red. Molecular docking simulations of both ligands were performed individually. Hydrogen atoms are omitted for clarity. The final structure was ray-traced and illustrated with the aid of PyMol Molecular Graphics.</p>
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<p>Levels of (<b>a</b>) tumor necrosis factor-α (TNF-α), and (<b>b</b>) interleukin-1β (IL-1β), in mixed cultures of primary neurons-microglia after treatment with LPS (1 μg/mL) in the presence or absence of 2 μΜ curcumin or V-Cur. Cytokine levels were determined with Western blotting (<b>c</b>,<b>d</b>). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was employed to verify equal loading. The density of the blots was semi-quantified with ImageJ 1.54. Results are presented as fractional changes in comparison with the control sample and are the mean (± SD) of three independent biological experiments. One-way ANOVA was employed to compare untreated or LPS-treated samples. Statistical significance when compared with: * untreated sample (control); # LPS-treated sample; <span>$</span> curcumin-treated: ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001; **** <span class="html-italic">p</span> &lt; 0.0001; # <span class="html-italic">p</span> &lt; 0.05; #### <span class="html-italic">p</span> &lt; 0.0001; <span>$</span><span>$</span> <span class="html-italic">p</span> &lt; 0.01.</p>
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14 pages, 11102 KiB  
Article
Wear and Optical Properties of MoSi2 Nanoparticles Incorporated into Black PEO Coating on TC4 Alloy
by Hao Zhang, Jiayi Zhu, Jingpeng Xia, Shang Sun and Jiaping Han
Coatings 2025, 15(1), 21; https://doi.org/10.3390/coatings15010021 - 29 Dec 2024
Viewed by 387
Abstract
Wear resistance and optical properties are the key point for the application of titanium alloys as structural materials in the aerospace field. To enhance the wear resistance and optical properties of titanium alloys, a black plasma electrolytic oxidation (PEO) coating incorporating MoSi2 [...] Read more.
Wear resistance and optical properties are the key point for the application of titanium alloys as structural materials in the aerospace field. To enhance the wear resistance and optical properties of titanium alloys, a black plasma electrolytic oxidation (PEO) coating incorporating MoSi2 nanoparticles was fabricated on the TC4 alloy via the PEO process, with the MoSi2 nanoparticles being in situ doped into the coating. The doping of MoSi2 nano-particles can effectively reduce the pore size of the PEO layer. The nPEO coating exhibited lower surface roughness than that of the PEO layer. The surface hardness of the nPEO coating increased to 42.5 HRC, significantly enhancing the wear resistance of the PEO layer (40.7 HRC). Furthermore, the PEO coatings exhibited better optical property compared to TC alloy, and the incorporation of MoSi2 particles further improved the performance in most wavelength ranges. The infrared emissivity of the nPEO coating was 0.87, a dramatic increase from the 0.38 value of the TC4 alloy. This coating strategy effectively enhances the wear resistance and optical performance of TC4 alloy, which is critical for the surface design of titanium alloys used in aerospace applications. Full article
(This article belongs to the Special Issue Advanced Alloy Degradation and Implants, 2nd Edition)
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<p>XRD patterns of TC4 alloy and the PEO coatings after 20 min of deposition.</p>
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<p>Surface morphology and elemental mappings of the PEO coatings after 20 min of deposition. (<b>a</b>) PEO and (<b>b</b>) nPEO, the numbers was the selected region for elemental analysis.</p>
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<p>Surface characteristics of TC4 alloy and the PEO coatings given by AFM and LSCM. (<b>a</b>) TC4, (<b>b</b>) PEO coating, (<b>c</b>) nPEO coating.</p>
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<p>Porosity and average pore size of the PEO coatings after 20 min of deposition.</p>
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<p>Cross-section morphology of the PEO coatings after 20 min of deposition. (<b>a</b>) PEO coating and (<b>b</b>) nPEO coating, the numbers was the selected region for elemental analysis.</p>
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<p>Friction coefficient of the specimens and the characteristics of the wear tracks. (<b>a</b>) Friction coefficient and (<b>b</b>) the characteristics of the wear tracks.</p>
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<p>Wear depth and width of the wear tracks and the surface hardness. (<b>a</b>) Wear depth and width and (<b>b</b>) surface hardness.</p>
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<p>Three-dimensional wear tracks of TC4 alloy and the PEO coatings. (<b>a</b>,<b>b</b>) TC4 alloy, (<b>c</b>,<b>d</b>) PEO coating, and (<b>e</b>,<b>f</b>) nPEO coating.</p>
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<p>Optical properties of TC4 alloy and the PEO coatings. (<b>a</b>) Absorptivity and (<b>b</b>) emissivity.</p>
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27 pages, 5540 KiB  
Article
Influence of Physicochemical Properties of Oil Sludge on Syngas Production for Energy Applications
by Hiago Oliveira, Isabela Pinheiro, Ana Ramos, Osvaldo Venturini, Adriano Mariano and York Santiago
Resources 2025, 14(1), 8; https://doi.org/10.3390/resources14010008 - 28 Dec 2024
Viewed by 384
Abstract
Oil sludge (OS) is a hazardous waste generated in the refinery and platform production chain. Its recovery is globally limited by methods like incineration, landfilling, and stabilization, which are costly and environmentally harmful. In Brazil, advanced techniques such as gasification are still underdeveloped [...] Read more.
Oil sludge (OS) is a hazardous waste generated in the refinery and platform production chain. Its recovery is globally limited by methods like incineration, landfilling, and stabilization, which are costly and environmentally harmful. In Brazil, advanced techniques such as gasification are still underdeveloped compared to established practices elsewhere. This study aims to characterize the chemical and physical properties of OS to enable its recovery through energy methods, reducing environmental impacts. OS samples from oil storage tanks were analyzed using mass spectrometry, thermogravimetry, atomic absorption, proximate analysis, X-ray fluorescence, and X-ray diffraction. The viscosity was approximately 34,793 cP, with 36.41% carbon and 56.80% oxygen. The ash content was 43.218% (w/w), and the lower and upper heating values were 17.496 and 19.044 MJ/kg, respectively. Metal analysis identified lead, vanadium, manganese, and chromium. The high ash content of OS reduced gasification temperatures, increasing char yield (44.6%). Increasing the equivalence ratio (ER) led to higher gasification temperatures, producing energetic species such as H2, CH4, and CO, raising the calorific value of the resulting syngas. Subsequently, this syngas was used in gas turbine models with GasTurb software 14.0, achieving electrical output and thermal efficiency of 66.9 kW and 22.4%, respectively. OS is a persistent waste requiring gasification treatment, offering a promising solution that converts these residues into valuable syngas for energy conversion with minimal environmental impact. Full article
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<p>Oil sludge sample (authors’ own creation).</p>
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<p>Elemental analysis process diagram (authors’ own creation).</p>
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<p>Schematic diagram of thermogravimetric analysis (authors’ own creation)<b>.</b></p>
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<p>Schematic diagram of atomic absorption analysis (authors’ own creation).</p>
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<p>Schematic of the entrained flow reactor used in the simulation (<b>a</b>); schematic of the fixed bed reactor used in the simulation (<b>b</b>), adapted from [<a href="#B50-resources-14-00008" class="html-bibr">50</a>].</p>
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<p>Schematic of gas turbine, adapted from GasTurb.</p>
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<p>Viscosity curve of the oil sludge used in this study (authors’ own creation).</p>
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<p>X-ray diffractogram of the petroleum sludge used in the study (authors’ own creation).</p>
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<p>Phases identified in the oil sludge used in the study (authors’ own creation).</p>
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<p>Temperature profiles in the bed for both (<b>a</b>) fixed bed and (<b>b</b>) entrained flow reactors (authors’ own creation).</p>
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<p>Molar profile in the bed for (<b>a</b>) C1, (<b>b</b>) C2, (<b>c</b>) C3, and (<b>d</b>) C4 (authors’ own creation).</p>
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<p>Temperature profile in various ERs for both (<b>a</b>) fixed bed and (<b>b</b>) entrained flow reactors (authors’ own creation).</p>
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<p>Char yield in different cases and ER (authors’ own creation).</p>
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<p>Thermal efficiency and thermal power for the different cases studied (authors’ own creation).</p>
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<p>Irreversibility of the gasifier, compressor, combustor, and turbine in the considered system (authors’ own creation).</p>
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23 pages, 10667 KiB  
Article
Post-Processing Thermal Activation of Thermoelectric Materials Based on Germanium
by Piotr Marek Markowski and Eugeniusz Prociów
Energies 2025, 18(1), 65; https://doi.org/10.3390/en18010065 - 27 Dec 2024
Viewed by 298
Abstract
After the deposition process, the lattice structure of doped germanium remains low. Post-processing annealing reorders the structure and increases the output parameters. Thin films of germanium doped with gold (Ge:Au) and vanadium (Ge:V) were magnetron-sputtered on glass substrates. The course of the activation [...] Read more.
After the deposition process, the lattice structure of doped germanium remains low. Post-processing annealing reorders the structure and increases the output parameters. Thin films of germanium doped with gold (Ge:Au) and vanadium (Ge:V) were magnetron-sputtered on glass substrates. The course of the activation process was monitored in situ. Two different methods of post-processing thermal activation of the films were studied. The first method was to place the structure at an elevated temperature for a specified period of time. The second method involved placing the structure on a heating table and cycling the heating and cooling several times from room temperature to about 823 K. Both methods fulfill their function well. The differences come down to research aspects. The best thermoelectric parameters were achieved for germanium doped with 0.95 at.% vanadium. The Seebeck coefficient of 212 μV/K and the power factor of 1.24 mW·m−1·K−2 were obtained at 500 K. Full article
(This article belongs to the Section J: Thermal Management)
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<p>The exemplary test structures fabricated on Corning 7059 substrates.</p>
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<p>The output parameters of the S1 structure, Ge:V (0.95 at.%): (<b>a</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the annealing time; (<b>b</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the temperature <span class="html-italic">T</span>, after the annealing process; (<b>c</b>) The generated electromotive force <span class="html-italic">E<sub>T</sub></span> versus the temperature difference between the hot and cold junction Δ<span class="html-italic">T</span>, after the annealing process; (<b>d</b>) The Seebeck coefficient <span class="html-italic">α</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process; (<b>e</b>) The Power Factor <span class="html-italic">PF</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process.</p>
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<p>The output parameters of the S2 structure, Ge:V (1.47 at.%): (<b>a</b>) The generated electromotive force <span class="html-italic">E<sub>T</sub></span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, before the annealing process (<span class="html-italic">t</span> = 0 min); (<b>b</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the temperature <span class="html-italic">T,</span> before the annealing process (<span class="html-italic">t</span> = 0 min); (<b>c</b>) The generated electromotive force <span class="html-italic">E<sub>T</sub></span> versus the temperature difference between the hot and cold junction Δ<span class="html-italic">T,</span> for different annealing times; (<b>d</b>) The Seebeck coefficient <span class="html-italic">α</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, for different annealing times; (<b>e</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the temperature <span class="html-italic">T</span>, for different annealing times; (<b>f</b>) The Power Factor <span class="html-italic">PF</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process.</p>
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<p>The output parameters of the S4 structure, Ge:Au (3.13 at.%): (<b>a</b>) The generated electromotive force <span class="html-italic">E<sub>T</sub></span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, before the annealing process (<span class="html-italic">t</span> = 0 min); (<b>b</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the temperature <span class="html-italic">T</span>, before the annealing process (<span class="html-italic">t</span> = 0 min); (<b>c</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the temperature <span class="html-italic">T</span>, for different annealing times; (<b>d</b>) The generated electromotive force <span class="html-italic">E<sub>T</sub></span> versus the temperature difference between the hot and cold junction Δ<span class="html-italic">T,</span> for different annealing times; (<b>e</b>) The Seebeck coefficient <span class="html-italic">α</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, for different annealing times; (<b>f</b>) The Power Factor <span class="html-italic">PF</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process.</p>
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<p>The output parameters of the S3 structure, Ge:V (0.6 at.%): (<b>a</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the temperature <span class="html-italic">T</span>, during the <span class="html-italic">heating</span>_1 process; (<b>b</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the temperature <span class="html-italic">T</span>, during all heating/cooling processes; (<b>c</b>) The generated electromotive force <span class="html-italic">E<sub>T</sub></span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process; (<b>d</b>) The Seebeck coefficient <span class="html-italic">α</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process; (<b>e</b>) The Power Factor <span class="html-italic">PF</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process.</p>
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<p>The output parameters of the S5 structure, Ge:Au (4.17 at.%): (<b>a</b>) The generated electromotive force <span class="html-italic">E<sub>T</sub></span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, before and after the annealing process; (<b>b</b>) The electrical resistance <span class="html-italic">R</span> and resistivity <span class="html-italic">ρ</span> versus the temperature <span class="html-italic">T</span>, during all heating/cooling processes; (<b>c</b>) The Seebeck coefficient <span class="html-italic">α</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process; (<b>d</b>) The Power Factor <span class="html-italic">PF</span> versus the temperature of the hot junction <span class="html-italic">T<sub>HOT</sub></span>, after the annealing process.</p>
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<p>SEM images of example films before the activation process (post-process annealing): (<b>a</b>) Ge:V; (<b>b</b>) Ge:Au.</p>
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<p>SEM/EDS results of S1 sample (Ge:V, 0.95 at.%): (<b>a</b>) SEM image; (<b>b</b>) Ge distribution in the film; (<b>c</b>) V distribution in the film; (<b>d</b>) EDS spectrum of the film.</p>
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<p>SEM/EDS results of S2 sample (Ge:V, 1.47 at.%): (<b>a</b>) SEM image; (<b>b</b>) Ge distribution in the film; (<b>c</b>) V distribution in the film; (<b>d</b>) EDS spectrum of the film.</p>
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<p>SEM/EDS results of S3 sample (Ge:V, 0.6 at.%): (<b>a</b>) SEM image; (<b>b</b>) Ge distribution in the film; (<b>c</b>) V distribution in the film; (<b>d</b>) EDS spectrum of the film.</p>
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<p>SEM/EDS results of S4 sample (Ge:Au, 3.13 at.%): (<b>a</b>) SEM image; (<b>b</b>) Ge distribution in the film; (<b>c</b>) Au distribution in the film; (<b>d</b>) EDS spectrum of the film.</p>
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<p>SEM/EDS results of S5 sample (Ge:Au, 4.17 at.%): (<b>a</b>) SEM image; (<b>b</b>) Ge distribution in the film; (<b>c</b>) Au distribution in the film; (<b>d</b>) EDS spectrum of the film.</p>
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16 pages, 5551 KiB  
Article
Determination of Diffusion Coefficients of Nickel and Vanadium into Stainless and Duplex Steel and Titanium
by Šárka Vávrová, Martin Švec, Jaromír Moravec and Daniel Klápště
Metals 2025, 15(1), 8; https://doi.org/10.3390/met15010008 - 27 Dec 2024
Viewed by 359
Abstract
When heterogeneous joints are created, problems with the formation of intermetallic phases arise. There are various ways to reduce the formation of intermetallics. One of the ways that is discussed in this article is to use a suitable interlayer of appropriate thickness when [...] Read more.
When heterogeneous joints are created, problems with the formation of intermetallic phases arise. There are various ways to reduce the formation of intermetallics. One of the ways that is discussed in this article is to use a suitable interlayer of appropriate thickness when forming the joint. A too-thin interlayer does not protect against the formation of brittle intermetallic phases. On the other hand, a too-thick interlayer increases the heterogeneity of the joint and, thus, decreases its useful properties. Within this paper, the formation of diffusion joints between the base material (AISI 304 steel, duplex steel, AISI 316L steel, or titanium grade 2) and the 0.2 mm thick intermediate layer (nickel or vanadium) was studied. Initial diffusion joints were prepared in a Gleeble 3500 machine, and samples for the study of diffusion kinetics were subsequently heat-treated in a vacuum furnace. The result of the research was the determination of specific diffusion parameters of nickel and vanadium into all four tested base materials. The initial diffusion depth (simple heating to the target temperature without holding at this temperature) of nickel was 4.46 µm into duplex steel and 5.48 µm into Ti Gr. 2 at 950 °C. At the same temperature, the initial diffusion depth of vanadium was 14.54 µm into duplex steel and 14.32 µm into Ti Gr. 2. In addition, general equations for the calculation of diffusion coefficients for the mentioned materials in the temperature range of 850 to 1150 °C were established. Full article
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<p>Temperature regime in the vacuum furnace—maximum temperature 950 °C and holding time 1 h.</p>
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<p>Clamped and heated sample in the Gleeble chamber.</p>
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<p>The appearance of a diffusion weld of the duplex steel with a nickel interlayer (left part of the joint) and AISI 304 steel with a nickel interlayer (right part of the joint).</p>
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<p>The maximum diffusion depth of nickel into duplex steel and Ti Gr. 2 at different temperatures and holding times.</p>
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<p>The maximum diffusion depth of vanadium into AISI 304, AISI 316L, duplex steel, and Ti Gr. 2 at different temperatures and holding times.</p>
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<p>Comparison of Ni concentration gradients for extreme temperature exposures.</p>
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<p>Comparison of vanadium concentration gradients for extreme temperature exposures.</p>
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<p>Dependence of log D<sub>Ni</sub> on 1/T for duplex and Ti gr. 2 and both 1 h and 5 h.</p>
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<p>Dependence of log D<sub>V</sub> on 1/T for AISI 304, AISI 316L, duplex steel, and Ti gr. 2 and both 1 h and 5 h.</p>
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<p>Diffusion from a 2 h wide sheet for different values of <math display="inline"><semantics> <mrow> <mstyle scriptlevel="0" displaystyle="true"> <mfrac> <mrow> <msqrt> <mi>D</mi> <mi>t</mi> </msqrt> </mrow> <mrow> <mi>h</mi> </mrow> </mfrac> </mstyle> </mrow> </semantics></math> [<a href="#B27-metals-15-00008" class="html-bibr">27</a>].</p>
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22 pages, 6314 KiB  
Article
Design and Optimization of W-Mo-V High-Speed Steel Roll Material and Its Heat-Treatment-Process Parameters Based on Numerical Simulation
by Zhiting Zhu, Mingyu Duan, Hao Pi, Zhuo Li, Jibing Chen and Yiping Wu
Materials 2025, 18(1), 34; https://doi.org/10.3390/ma18010034 - 25 Dec 2024
Viewed by 286
Abstract
W-Mo-V high-speed steel (HSS) is a high-alloy high-carbon steel with a high content of carbon, tungsten, chromium, molybdenum, and vanadium components. This type of high-speed steel has excellent red hardness, wear resistance, and corrosion resistance. In this study, the alloying element ratios were [...] Read more.
W-Mo-V high-speed steel (HSS) is a high-alloy high-carbon steel with a high content of carbon, tungsten, chromium, molybdenum, and vanadium components. This type of high-speed steel has excellent red hardness, wear resistance, and corrosion resistance. In this study, the alloying element ratios were adjusted based on commercial HSS powders. The resulting chemical composition (wt.%) is C 1.9%, W 5.5%, Mo 5.0%, V 5.5%, Cr 4.5%, Si 0.7%, Mn 0.55%, Nb 0.5%, B 0.2%, N 0.06%, and the rest is Fe. This design is distinguished by the inclusion of a high content of molybdenum, vanadium, and trace boron in high-speed steel. When compared to traditional tungsten-based high-speed steel rolls, the addition of these three types of elements effectively improves the wear resistance and red hardness of high-speed steel, thereby increasing the service life of high-speed steel mill-roll covers. JMatPro (version 7.0) simulation software was used to create the composition of W-Mo-V HSS. The phase composition diagrams at various temperatures were examined, as well as the contents of distinct phases within the organization at various temperatures. The influence of austenite content on the martensitic transformation temperature at different temperatures was estimated. The heat treatment parameters for W-Mo-V HSS were optimized. By studying the phase equilibrium of W-Mo-V high-speed steel at different temperatures and drawing CCT diagrams, the starting temperature for the transformation of pearlite to austenite (Ac1 = 796.91 °C) and the ending temperature for the complete dissolution of secondary carbides into austenite (Accm = 819.49 °C) during heating was determined. The changes in carbide content and grain size of W-Mo-V high-speed steel at different tempering temperatures were calculated using JMatPro software. Combined with analysis of Ac1 and Accm temperature points, it was found that the optimal annealing temperatures were 817–827 °C, quenching temperatures were 1150–1160 °C, and tempering temperatures were 550–610 °C. The scanning electron microscopy (SEM) examination of the samples obtained with the aforementioned heat treatment parameters revealed that the martensitic substrate and vanadium carbide grains were finely and evenly scattered, consistent with the simulation results. This suggests that the simulation is a useful reference for guiding actual production. Full article
(This article belongs to the Special Issue Advanced Materials: Process, Properties, and Applications)
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<p>(<b>a</b>) Effect of carbon content in austenite on the amount of residual austenite; (<b>b</b>) effect of carbon content in austenite on martensitic transformation temperature [<a href="#B37-materials-18-00034" class="html-bibr">37</a>].</p>
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<p>Equilibrium-phase diagrams of Fe-5.5W-5.0Mo-5.5V-4.5Cr-0.7Si-0.55Mn-0.5Nb-0.2B-0.06N-1.9C high-speed steels at different temperatures (the numbers indicate weight percent).</p>
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<p>Analysis of elemental content in HSS Fe-5.5W-5.0Mo-5.5V-4.5Cr-0.7Si-0.55Mn-0.5Nb-0.2B-0.06N-1.9C: (<b>a</b>) elemental content in ferrite; (<b>b</b>) elemental content in austenite.</p>
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<p>Analysis of the content of different carbides in Fe-5.5W-5.0Mo-5.5V-4.5Cr-0.7Si-0.55Mn-0.5Nb-0.2B-0.06N-1.9C high-speed steel. (<b>a</b>) Elemental content in MN; (<b>b</b>) elemental content in M (C, N); (<b>c</b>) elemental content in M<sub>6</sub>C; (<b>d</b>) elemental content in M<sub>23</sub>C<sub>6</sub>.</p>
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<p>Analysis of elemental content in M<sub>3</sub>B<sub>2</sub> borides in Fe-5.5, W-5.0Mo-5.5V-4.5Cr-0.7Si-0.55Mn-0.5Nb-0.2B-0.06N-1.9C high-speed steel.</p>
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<p>Schematic diagram of several spheroidal annealing processes for alloy steels.</p>
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<p>Carbon content of austenite at different temperatures.</p>
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<p>Fe-5.5W-5.0Mo-5.5V-4.5Cr-0.7Si-0.55Mn-0.5Nb-0.2B-0.06N-1.9C. Variation of carbide content of each carbide with the tempering time at different tempering temperatures of high-speed steels: (<b>a</b>) 550 °C; (<b>b</b>) 580 °C; (<b>c</b>) 610 °C; (<b>d</b>) 640 °C; (<b>e</b>) 670 °C; (<b>f</b>) 700 °C; (<b>g</b>) 730 °C; (<b>h</b>) 760 °C.</p>
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<p>Fe-5.5W-5.0Mo-5.5V-4.5Cr-0.7Si-0.55Mn-0.5Nb-0.2B-0.06N-1.9C. Variation of carbide grain size with tempering time in high-speed steels at different tempering temperatures: (<b>a</b>) 550 °C; (<b>b</b>) 580 °C; (<b>c</b>) 610 °C; (<b>d</b>) 640 °C; (<b>e</b>) 670 °C; (<b>f</b>) 700 °C; (<b>g</b>) 730 °C; (<b>h</b>) 760 °C.</p>
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<p>SEM photos after quenching at different temperatures. (<b>a</b>) 1180 °C × 100; (<b>b</b>) 1160 °C × 100.</p>
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<p>Strength of W-Mo-V high-speed steels at different temperatures.</p>
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