High Vanadium Content Research Articles

Electron beam welding of the novel L12 nanoparticles-strengthened medium-entropy alloy Ni41.4Co23.3Cr23.3Al3Ti3V6: Microstructures, mechanical properties, and fracture

Although low levels of vanadium-doping can enhance the friction stress and strength of L12-nanoparticles strengthened medium-entropy alloys (MEA), how high concentrations of vanadium affect the weldability, microstructure, mechanical properties, and fracture behavior remains unknown. In this work, we designed a vanadium-doped, L12-nanoparticle-strengthened MEA Ni41.4Co23.3Cr23.3Al3Ti3V6 (at.%), which showed a high fracture toughness of 238 MPa × m1/2, a high friction stress of 410 MPa, and a Hall-Petch strengthening coefficient of 782 MPa × μm1/2. Pieces of the HEA were joined using electron-beam welding (EBW). Strong yet ductile defect-free joints were produced which had coarse columnar grains (88 μm) with a {110}<001> texture in the fusion zone, which was larger than the equiaxed grains in the heat-affected zones (14.9 μm) which had strong {110}<001> and relatively weak {110}<112> texture. In contrast, the base materials had fine grains (2.2 μm) with a strong {110}<111> and a relatively weak {110}<112> texture. The EBWed MEA showed a high yield strength of 599 MPa, a high ultimate tensile strength of 939 MPa, a good fracture strain of 20 %, and a fracture toughness of 198 MPa × m1/2, which were 75 %, 83 %, 58 %, and 83 %, respectively, of the values of for the thermo-mechanically treated counterpart. The reduced strength arose from the coarse columnar grains, while the reduced fracture strain and fracture toughness could be ascribed to the reduced deformation twinning and the absence of annealing twins, which produced a poor strain hardening capability. The EBWed MEA exhibited abundant dislocation networks, indicating that a high concentration of vanadium inhibited the occurrence of stacking faults and nanoscale deformation twins.

Associations between maternal blood metal concentrations during the first trimester and spontaneous preterm birth: a nested case-control study

BackgroundFew studies have utilized whole blood samples to investigate the association between metal mixture exposure during early pregnancy and spontaneous preterm birth (SPB). We conduct this nested case–control study to investigate both the independent and joint effect of each metal, and identify critical metals in the metal mixture.ResultsA total of 120 pregnant women with SPB and 120 pregnant women with full-term delivery were selected from the prospective birth cohort. We measured 14 metal concentrations in maternal blood collected during 10–13 weeks gestation. Conditional logistic regression showed that high concentrations of vanadium (V), magnesium, and copper were positively associated with SPB (Adjusted OR = 5.76 (95% CI 2.46–13.53), 3.64 (95% CI 1.64–8.09), 2.88 (95% CI 1.29–6.41), respectively). Moderate manganese (Mn) concentration (50th–75th percentile) group had the lowest estimated OR (Adjusted OR = 0.32 (95% CI 0.13–0.76)). The high level of strontium (Sr) was negatively associated with SPB (Adjusted OR = 0.39 (95% CI 0.17–0.91)). The BKMR model showed a significant positive joint effect of metal mixture exposure on SPB, while V was the most important metal. The non-linear effects of V and lead (Pb) on SPB, and the interaction effects between V–Pb, Sr–Mn were also revealed.ConclusionsMaternal blood metal mixtures in the first trimester were found to be positively associated with SPB, with V exhibiting the strongest independent association. Mn had a potential U-shaped association with SPB. Elimination of metal contamination in the environment has a positive impact on maternal and child health.

Efficient reduction of vanadium (V) with biochar and experimental parameters optimized by response surface methodology

Water pollution deteriorates ecosystems and has a great threaten to the environment. The environmental benefits of wastewater treatment are extremely important to minimize pollutants. Here, the biochar purchased from the related industry was used to treat the wastewater which contained high concentration of vanadium (V). The concentration of vanadium was measured by the IC-OES and the results showed that 96.1% vanadium (V) was reduced at selected reaction conditions: the mass ratio of biochar to vanadium of 5.4, reaction temperature of 90 °C, reaction time at 60 min and concentration of H2SO4 of 10 g/L, respectively. Response surface methodology confirmed that all the experimental parameters had positive effect on the reduction of vanadium (V), which could improve the reduction efficiency of vanadium (V) as increased. The influence of each parameter on the reduction process followed the order: A (Concentration of H2SO4) > C (mass ratio of biochar to vanadium) > B (mass ratio of biochar to vanadium). Especially, the mass ratio of biochar to vanadium and concentration of H2SO4 had the greatest influence on the reduction process. This paper provides a versatile strategy for the treatment of wastewater containing vanadium (V) and shows a bright tomorrow for wastewater treatment.

Effect of tempering temperature on stress corrosion resistance of a low alloy high strength steel with high vanadium content

The stress corrosion resistance of a low alloy high strength steel with high vanadium content, tempered at different temperatures, was examined by electrochemical measurements and slow strain rate tensile test under different environments. Combined with scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM), the results show that three different tempering temperatures had an influence on the microstructure of this steel as well as its electrochemical behavior and stress corrosion sensitivity. With the increase of tempering temperature, the ferrite grains coarsened, the average dislocation density lowered as well as the number of vanadium carbide also decreased, though the size of vanadium carbide increased. However, the interface distortion between vanadium carbide and matrix exacerbated, resulting in the increase of the local dislocation density. Therefore, the corrosion potential and impedance decreased, meantime, the stress corrosion sensitivity aggravated.

Short-range ordering mechanics in FCC materials

Short-range order (SRO) has a crucial impact on the mechanical strength of metallic alloys. Recent atomistic investigations defined an average SRO and attempted to correlate it with the yield strength. We propose that the local change in SRO upon slip advance must dictate the strengthening, and we elaborate the methodology to establish the “SRO change” on a slip plane considering the Wigner-Seitz cell. The model captures the variation of lattice resistance (Critical Resolved Shear Stress; CRSS) in the crystal as the SRO changes depending on the probability of neighboring atoms. The methodology was applied to Ni-V binary alloys for a wide range of compositions and stacking fault widths. Dislocation core widths were determined as a function of SRO and energy parameters (unstable and intrinsic stacking fault energies; γus, γisf). The complex variation of CRSS with compositional variations shows good agreement with limited experimental results. The compositions corresponding to the transition from partial to full dislocations at higher vanadium contents are found depending on the SRO and the intrinsic energy levels.

Assessment and Review of Heavy Metals Pollution in Sediments of the Mediterranean Sea

The impact of marine sediment pollution is crucial for the health of the seas, particularly in densely populated coastal areas worldwide. This study assesses the concentration and distribution of heavy metals in the marine sediments of the main regions of the Mediterranean Sea. The results underscore high concentrations of mercury (Hg), nickel (Ni), and copper (Cu), whereas chromium (Cr), zinc (Zn), cadmium (Cd), barium (Ba), and vanadium (V) exhibit moderate values. To assess the heavy metal results, sediment quality guidelines and pollution indices (Igeo and Geochemical Signal Type-GST) were employed, revealing a consistent trend of decreasing concentrations from the coastal zone to the open sea. Principal Component Analysis (PCA) emphasizes the significant roles of Cu, Zn, Ba, and Cr in sediment chemistry. The study suggests that the distribution patterns of heavy metals are linked to wastewater discharges in coastal areas, requiring effective management strategies to ensure the health of the Mediterranean Sea.

Borate speciation and structural studies of vanadium ion doping in borate bioglass

Different glasses in the system, xV2O5-(45–x)B2O3–24.5Na2O–24.5CaO–6P2O5, (x = 0, 3, 6, 9, 12, 15, 18, 20 and 25 Wt%) were prepared through melt quenching method. X-ray diffraction (XRD) patterns have revealed that the amorphous structure is the dominant type. There is no tendency for crystallization even with higher vanadium content. Crystallization occurred utilizing treating the glasses thermally. FTIR spectral absorption data showed the presence of both BO3 and BO4 structural groups in combination with the presence of VO4 and VO5 structural building units. The deconvolution analysis technique (DAT) was adopted to retrace the conversion progressions of the coordinated boron. At low V2O5 content (up to 10 wt%), it entered as a glass modifier as well as both Na2O and CaO. The high content of the glass modifier (Na2O + CaO + V2O5) could destroy some of the well-formed BO4 units which are transformed into asymmetric BO3. The back conversion of BO4 to asymmetric or loose BO3 can simply reduce the fraction of tetrahedral units (N4). When V2O5 entered as a glass former (> 10 wt%), the N4 fraction increased. The change in the measured densities and estimated molar volumes may assigned to the formation of BO4 units resulting from increasing vanadium oxide content.

Peculiar catalytic properties of oxide glass-(ceramics) in epoxidation reactions

Glass-(ceramic) samples were prepared by melting mixtures of Na2O-V2O5-(Al2O3)-P2O5-Nb2O5 in various molar ratios, and their catalytic performances were correlated to the structural, thermal, and electrical properties. The catalysts were tested in an epoxidation reaction, with tert‑butyl hydroperoxide in decane and water as oxidants. Samples containing the highest vanadium content are highlighted as the best catalysts (cyclooctene conversion 70–90 %), highly selective towards the desired epoxide (70–80 %). At the same time, high electrical conductivity is observed with the value of ∼10–5 S cm–1 @30 °C, which is 4–6 orders of magnitude higher in comparison to other studied samples.

Consideraciones generales sobre la génesis de la ocurrencia de uranio y vanadio en las rocas sedimentarias Cretácicas del Sinclinal de Berlín Cordillera Central (Andes Colombianos)

The mineralization at the Berlin project in Colombia presents a huge interest based on its relatively high uranium and vanadium concentrations (0.11% U3O8) and (0.45% V2O5), with a suite of other economically interesting elements, all of them necessary to achieve the energy transition, including Y, Re, Ag, and P. The present research suggests a hypothesis for the U and V mineralization: an epigenetic origin. The results indicate that the source for U, V, and the other economic elements associated, were released from the black shales of the Abejorral Formation that is overlying a carbonate succession of Cretaceous wackestone. Those elements were transported in diagenetic fluids under specific physical and geochemical conditions. Efficient strata-bound trap occurred when the carbonate succession triggered a redox front that interacted not only with mineralized fluids, but organic matter and H2S.

Biomonitoring of the environment of the Arctic urbanized area using the pollen of Sorbus gorodkovii Pojark

This article investigates the content of heavy metals (Cu, Ni, V, Cd, Zn) in the reproductive organs of the Gorodkov’s rowan (Sorbus gorodkovii Pojark.) growing in the impact zone of environmentally hazardous facilities in Murmansk (CHP plants, waste incineration plant and trade sea port). The samples most contaminated by heavy metals were registered in the vicinity of the incineration plant. High concentrations of vanadium (4,2–4,8 mg/kg) and Cu, Ni, Cd, and Zn exceeding the limits of MPC are revealed in the impact zone of CHP plants operating on fuel oil. Biomonitoring of the viability of S. gorodkovii pollen showed that in all samples, the content of fertile pollen grains was reduced compared to that in the control. At the test sites of the Central and South CHP plants, the proportion of fertile pollen was 35–41 % (compared to 72 % in the control sample). The induced sterility was more than two times higher than the spontaneous sterility. High concentrations of vanadium and other toxic metals in emissions of Heating Plants have a gametocidal effect on the male gametophyte of S. gorodkovii. Groups of fertile and sterile pollen grains were selected according to their size: dwarf, normal, or hypertrophied. In the vicinity of the CHP plants, the proportion of fertile pollen of normal size decreased (62–69 %), whereas the content of dwarf (16–18 %) and hypertrophic pollen (17.4–22.7 %) increased. Sterile pollen grains were mostly dwarf (63–70 %). The results of biomonitoring indicated that CHP plants polluted the urban environment with vanadium and other toxic metals, which caused sterilization of S. gorodkovii male gametes. To improve the ecological situation in Murmansk, it is necessary to switch the thermal stations for the use of natural gas.

Simultaneous elimination of vanadium(V) and sulfamethoxazole from livestock wastewater with nitrogen-impregnated biochar

A cross-linked chitosan-modified birch sawdust biochar (CS@BSBC) was prepared and applied for the simultaneous elimination of vanadium (Ⅴ) and sulfamethoxazole (SMX) from livestock wastewater. The adsorption capacity of V(V) reached 110 mg/g alone while this value was promoted to 150 mg/g for the simultaneous removal of SMX and V(V), and the adsorption effect is optimal at pH 3. The adsorption capacity of SMX reached about 30 mg/g alone, while the SMX’s adsorption capacity droped to 25 mg/g for the simultaneous removal of SMX and V(V). The mechanism studies disclosed that redox reactions occur on the surface of CS@BSBC. As revealed by the XPS spectra, 63 % of V(V) was reduced to V(IV) concurrently pyrolic nitrogen and C−O terminals were oxidized to nitrogen oxide and CO. The treatment mechanism of CS@BSBC described above can provide a reference for the subsequent treatment of livestock wastewater with complex composition and high vanadium content.

Synthesis and Hydrogenation of the Ti45−xVxZr38Ni17 (5 ≤ x ≤ 40) Mechanically Alloyed Materials

The mechanically alloyed amorphous alloys of the Ti45Zr38Ni17 composition are known for their ability to form a quasicrystalline state after thermal treatment. It is also known that the amorphous and quasicrystal alloys belonging to the Ti45Zr38Ni17 family are able to store hydrogen and yield gravimetric densities above 2 wt.%. In this contribution, we report the results of research on the Ti45Zr38Ni17 system with vanadium doped instead of titanium. We found that the amorphous samples with moderate doping (x &lt; 20) show the ability to absorb hydrogen while maintaining the amorphous state and they transform into the novel glassy-quasicrystal phase during annealing. Those materials with higher vanadium concentrations do not form entirely amorphous structures. However, they still can absorb hydrogen easily. It was also confirmed that the in situ hydrogenation of the amorphous alloys is a straightforward process without decomposition of the alloy. In this process, hydrogen does not attach to any particular constituent of the alloy, which would lead to the formation of simple hydrides or nanoclusters. Therefore, we were able to confirm the fully amorphous nature of the deuterides/hydrides of the Ti45−xVxZr38Ni17 with moderate V doping.

Effect of Heat Treatment on Microstructure and Properties of Quenched and Tempered Steel with High Vanadium Contents

After heat treatment, the microstructure of quenched and tempered (Q&T) steel with high vanadium (V) content was characterized using metallographic and scanning electron microscopes (SEM). The proto-austenite grains of the tested steel were compared at different quenching temperatures, and the precipitation behavior of precipitates and matrix microstructure characteristics at various tempering temperatures were studied. Tensile properties and low-temperature impact toughness of the tested steel with different heat treatments were measured using an electronic universal testing machine and an impact testing machine. The findings indicate that as the quenching temperature increases, the size of the proto-austenite grains gradually increases. When the quenching temperature surpasses 920 °C, the size of the proto-austenite grains obviously increases. With a constant tempering temperature, an increase in quenching temperature results in a decrease in the size of precipitates. With a constant quenching temperature, an increase in tempering temperature results in an increase in the size of precipitates. Therefore, the tested steel quenched at 920 °C for 1 hour and then tempered at 630 °C for 1.5 hours would obtain excellent comprehensive mechanical properties, with a tensile strength of 1233 MPa and a low-temperature impact value of 64 J.

Responses of rhizosphere microbial community structure and metabolic function to heavy metal coinhibition.

Metal mineral mining results in releases of large amounts of heavy metals into the environment, and it is necessary to better understand the response of rhizosphere microbial communities to simultaneous stress from multiple heavy metals (HMs), which directly impacts plant growth and human health. In this study, by adding different concentrations of cadmium (Cd) to a soil with high background concentrations of vanadium (V) and chromium (Cr), the growth of maize during the jointing stage was explored under limiting conditions. High-throughput sequencing was used to explore the response and survival strategies of rhizosphere soil microbial communities to complex HM stress. The results showed that complex HMs inhibited the growth of maize at the jointing stage, and the diversity and abundance of maize rhizosphere soil microorganisms were significantly different at different metal enrichment levels. In addition, according to the different stress levels, the maize rhizosphere attracted many tolerant colonizing bacteria, and cooccurrence network analysis showed that these bacteria interacted very closely. The effects of residual heavy metals on beneficial microorganisms (such as Xanthomonas, Sphingomonas, and lysozyme) were significantly stronger than those of bioavailable metals and soil physical and chemical properties. PICRUSt analysis revealed that the different forms of V and Cd had significantly greater effects on microbial metabolic pathways than all forms of Cr. Cr mainly affected the two major metabolic pathways: microbial cell growth and division and environmental information transmission. In addition, significant differences in rhizosphere microbial metabolism under different concentrations were found, and this can serve as a reference for subsequent metagenomic analysis. This study is helpful for exploring the threshold for the growth of crops in toxic HM soils in mining areas and achieving further biological remediation.

Development of Fe-containing BCC hydrogen storage alloys with high vanadium concentration

Vanadium-based alloys are promising hydrogen storage materials which reversibly absorb hydrogen > 2.0 wt% under ambient conditions. In present study, we systematically investigated the V-Ti-Cr-Fe quaternary alloys with V concentration of 65–80 at% and discussed the relationship between hydrogen sorption properties and lattice parameter (a) and valence electron density (e/a). When 3.023 ≤ a ≤ 3.031 Å and e/a ≤ 5.12, the alloys show the hydrogen desorption amount ≥ 2.30 wt% and desorption plateau pressure ≥ 0.1 MPa at 298 K. More interestingly, compared to the Fe-free V75-Ti-Cr (Ti/Cr = 0.9) alloy, addition of 1–3 at% Fe could improve the hydrogen desorption amount and plateau pressure. The optimized alloy, V75-Ti-Cr-Fe2 (Ti/Cr = 0.9), shows a reversible hydrogen capacity of 2.46 wt% at 298 K in the 1st cycle and the capacity retention rate of 96 % after 100 cycles.

Fabrication and abrasive wear property of high chromium cast iron with high vanadium and high nitrogen content (HCCI-VN)

High chromium cast irons (HCCIs) have excellent wear resistance because of high hardness chromium carbides (M7C3). However, the hardness of M7C3 is relatively low compared with MC-type carbides, such as VC, NbC and TiC. To improve wear resistance of HCCI, a new HCCI, named HCCI-VN, was fabricated by replacing wt.5.0% chromium with 5.0 wt% vanadium and adding 0.1 wt% nitrogen in traditional HCCI with 20 wt% Cr, and the abrasive wear properties of HCCI-VN were researched under different abrasive size and load conditions. Results show that the microstructure of HCCI-VN was characterized by many V(C, N) carbides besides chromium and molybdenum carbides (M7C3, M23C6, M2C), which were distributed in the matrix composed of martensite and austenite. The new HCCI-VN has excellent wear resistance. The relative wear resistance HCCI-VN is 2.2–9.1 times that of HCCI with 23 wt% Cr under different abrasive size and wear load. Among them, the reduction of abrasive size or the increase of wear load will bring better wear resistance. The excellent wear resistance of HCCI-VN is attributed to high hardness V(C, N), which cooperates with multi-scale and multi-type chromium and molybdenum carbides to resist abrasive scratch efficiently.

Influence of production technology of powder high-speed steels on the complex of formed properties

The authors analyzed the state of tool production in Russia. The main manufacturing companies and the main brands of materials used in the production of domestic tools are highlighted. Powder high-speed steels are practically not used in the domestic market, but they are widely distributed in the foreign market of tool steels due to their significant advantages in terms of basic and technological properties (including the possibility of using high-carbon and high-alloy high-speed steels). There is a new group of economically alloyed tungsten-free high-speed steels with a high content of carbon and vanadium, which are practically impossible to manufacture and apply in our traditional technology due to low technological properties. The authors give recommendations on the technology of manufacturing such steels by powder metallurgy and on the modes of their heat treatment. The paper studies a set of properties of these steels, including: basic mechanical properties (hardness, bending strength, toughness, and heat resistance), basic technological properties (pressure, cutting, grinding) and operational properties (evaluated by tool durability during turning). Structural and phase compositions of the steels and their influence on the basic and technological properties were investigated. The compaction mode affects the density of the billets. The paper presents distribution of alloying elements in the microstructure of powder high-speed steel and results of their relative grindability. Also the durability of tools was tested. There are significant advantages of high-carbon high-vanadium high-speed steels, especially in terms of technological properties, compared with traditional high-speed steels. It is possible to produce high-alloy tool steels using inexpensive carbide-forming alloying elements. The steels under consideration can be used to manufacture a wide range of tools, including hot-forming die tools. The use of powder technology opens up the prospect of developing universal economically alloyed powder tool steels.

The Influence of High Vanadium and Phosphorus Contents on the Risk of Transverse Cracking during the Continuous Casting of Austenitic TWIP Steels

There is considerable interest in improving the resistance of fully austenitic TWIP steels to hydrogen embrittlement; one potential route is to use V additions to promote hydrogen trapping by V(C,N) precipitates. This has the dual benefit of increasing the yield strength through precipitation strengthening and grain refinement. However, the effect on slab quality during continuous casting has not been determined. In this study, the hot ductility of two twinning-induced plasticity (TWIP) steels, Fe-0.6C-22Mn and Fe-0.6C-22Mn-0.2V, was examined over the temperature range 650–1200 °C. Tensile samples were taken from continuous cast 225 mm slabs and from 36 mm transfer bars. The addition of V caused the ductility trough in the temperature range 650–900 °C to deepen and widen and the lowest reduction in area (RA) recorded in the as-cast condition was 30%. This deterioration of hot ductility was due to V(C,N) precipitation. Even though the minimum RA was below the value often accepted to avoid cracking, no transverse cracking was observed in industrial trials and the surface quality was acceptable. The RA values of Fe-0.6C-22Mn were found to be very sensitive to the P level. However, this sensitivity was less evident when V was added, possibly due to P trapping by VC at austenite boundaries. No transverse cracking was observed in industrially produced slabs with P in the range examined (0.02 to 0.04 wt.% P).

Operando UV/Vis spectra deconvolution for comprehensive electrolytes analysis of vanadium redox flow battery

• 0.5 and 1 M vanadium electrolytes were successfully analyzed using the method. • The analysis provides reliable data regardless of supporting electrolyte composition. • V 2 O 3 3+ complex of posolyte was obtained using the proposed method. • Unknown residual absorbance of negolyte was registered using the deconvolution. • The method provides comprehensive data during VRFB cycling. Monitoring the state of charge (SoC) is one of the most important challenges of vanadium redox flow battery (VRFB) technology to solve. Among other methods, optical spectroscopy seems promising, however, existing approaches have their problems, primarily because of limited applicability for high vanadium concentrations, uncertainty in accounting for electrolyte imbalance during VRFB operation, and applicability limitations for mixed acid electrolytes. In this work, a method for determining SoC of VRFB based on the deconvolution of electrolyte absorption spectra is proposed. This method was successfully implemented for 0.5 M and 1 M vanadium electrolytes with 0.05 M phosphoric acid additive and demonstrated good accuracy for determining vanadium concentration and SoC in both half-cells, including analysis during VRFB galvanostatic cycling. Besides, this method allows us to obtain complex spectra: V 2 O 3 3+ in posolyte and a previously never demonstrated complex in negolyte that presumably corresponds to the V 3+ complex.

Analysis of the use of magnesium-containing additives in the charge of iron flux in order to reduce CO2 emissions

The growing requirements for the quality of finished steel products oblige to obtain steel with a low content of harmful impurities, especially sulfur. The main charge for steel production in the conditions of JSC EVRAZ NTMK is vanadium iron, the external desulfurization of which leads to large losses of valuable vanadium. Therefore, the smelting of iron with a low sulfur content is an urgent task. The main way to reduce sulfur in iron is to increase the basicity of the slag (B2), but MgO is the best desulfurizer. The paper evaluates the effectiveness of the use of various magnesium-containing materials in the conditions of the blast-furnace stage of JSC EVRAZ NTMK, taking into account CO2 emissions. The possibility of replacing limestone in the iron flux charge with dolomite, as well as with steel converter slag, is considered. Both materials will increase the proportion of MgO in blast-furnace slag, however, the use of dolomite is accompanied by a two-fold increase in CO2 emissions compared to limestone. Converter steel slag (CSS) does not contain carbonates, thus eliminating the formation of CO2 during the limestone decomposition. An additional advantage of CSS is its high content of valuable vanadium and manganese. The effect of an increase in MgO in slag on its melting point is considered. It has been established that an increase in the proportion of MgO to 14% will not cause difficulties in the processing of blast-furnace smelting products and will reduce the sulfur content in iron and the formation of titanium carbides and carbonitrides.