Chromium Research Articles

Phase evolution in Ni-based superalloy K439B during thermal process

Based on the difference in element distribution and diffusion in various regions, the phase transformation of the as-cast, heat-treated and long-term aged K439B superalloys was investigated. Ti, Nb, Ta and Al elements segregated to the interdendritic regions, whereas W, Co and Cr elements segregated to the dendrite core regions in the as-cast alloy. During thermal process, the γ/γ' eutectic and the irregular γ' phase formed in the as-cast alloy completely dissolved into γ matrix. Subsequently, the reprecipitated spherical γ' phase gradually grew up and tended to be cubic. γ' phase was surrounded by the dislocations and a few stacking faults, which reduced the elastic strain energy in the long-term aged alloy. In addition, the degeneration of MC carbide was caused by a discrepancy in element diffusion rate and driving force in the interdendritic and grain boundary regions. The degeneration of MC carbide promoted the precipitation of γ' phase, M23C6 carbide and η phase, M23C6 carbide precipitated from γ matrix and γ' phase transformed into η phase. The preferential precipitation of M23C6 carbide was related to the difference in crystal structure, precipitation temperature range and Gibbs free energy.

Microstructure and properties of novel nano-lamellar Al27Nb18(CrZr0.5)xTi55−1.5x eutectic high-entropy alloy coatings on Ti-6Al-4V alloy

The serious wear damage caused by low surface hardness and poor wear resistance of titanium alloy severely limits its further application in engineering field. In this work, novel eutectic high entropy alloys (EHEAs) were designed by means of infinite solution strategy combined with mechanical assistance to explore the application of EHEAs in the field of surface protection coating. Three types of EHEA coatings were achieved through the adjustment of the Cr and Zr element proportions on Ti-6Al-4V alloy by laser cladding. The microstructure was eutectic structure composed of Laves and BCC/B2 phases with superlattice structure. A significant presence of stacking faults, Lomer-Cottrell locks and other defects is observed within the BCC/B2 phase, which contributes to the enhancement of both microhardness and nano-hardness. Al27Cr25Ti18Nb18Zr12 coating showed excellent wear resistance and minimal volume loss, which are 0.340 (65.38 % of the substrate) and 6.71 × 10−5 mm3/N·m (16.89 % of the substrate). Notably, the three alloys exhibit interesting selective corrosion behavior, which is mitigated by the presence of a nano-lamellar eutectic structure that limits pitting propagation.

Doping TiO<sub>2</sub> with Cr and Cu Elements from Electroplating Wastewater as a Single Source for Improvement of the Photocatalyst Activity under Visible Light in the Degradation of Anionic Surfactant

Doping TiO<sub>2</sub> with Cr and Cu Elements from Electroplating Wastewater as a Single Source for Improvement of the Photocatalyst Activity under Visible Light in the Degradation of Anionic Surfactant

Mineral Nutrition In The Leaves of Cocculus hirsutus (L) Under Pathogenesis

The present research paper deals with mineral content in the leaves of Cocculus hirsutus(L) affected by powdery mildew fungus Oidium Sp. (Imperfect stage). The healthy and infected leaves were digested by tri-acid, prescribed by Toth et al., (1948) method. The digested sample was further subjected to Inductive Coupled Plasma Optical Emission spectroscopy. ICP-OES (Agilent 5800ICP-OES FEQ’S), MY 1523001 software version: 7.3.0.8799. Firm ware version: 3354 for analysis of mineral element. The infected leaf shows enhanced content in potassium, iron, manganese, copper, nickel, chromium, and aluminium element. On the Contrary, elements such as magnesium, sodium, calcium, lead, zinc, boron, strontium and thallium were reduced in their contents reflect a high metabolic activity during pathogenesis.

Physicochemical Properties of (La,Sr)CoO3 Thick Films on Fe-25Cr Steel under Exposure to SOFC Cathode Operating Conditions.

La0.6Sr0.4CoO3 (LSC) coatings with a thickness of 50-100 µm were deposited on Fe-25Cr ferritic stainless steel (DIN 50049) via screen printing. The required suspension had been prepared using fine LSC powders synthesised using EDTA gel processes. In its bulk form, the LSC consisted entirely of the rhombohedral phase with space group R-3c, and it exhibited high electrical conductivity (~144 S·cm-1). LSC-coated steel was oxidised in air at 1073 K, i.e., under conditions corresponding to SOFC cathode operation, for times of up to 144 h. The in situ electrical resistance of the steel/La0.6Sr0.4CoO3 layered system during oxidation was measured. The products formed on the samples after the oxidation reaction resulting from exposure to the corrosive medium were investigated using XRD, SEM-EDS, and TEM-SAD. The microstructural, nanostructural, phase, and chemical analysis of films was performed with a focus on the film/substrate interface. It was determined that the LSC coating interacts with the oxidised steel in the applied conditions, and a multi-layer interfacial zone is formed. Detailed TEM-SAD observations indicated the formation of a main layer consisting of SrCrO4, which was the reaction product of (La,Sr)CoO3, and the Cr2O3 scale formed on the metal surface. The formation of the SrCrO4 phase resulted in improved electrical conductivity of the investigated metal/ceramics layered composite material, as demonstrated by the low area-specific resistance values of 5 mΩ·cm2, thus making it potentially useful as a SOFC interconnect material operating at the tested temperature. In addition, the evaporation rate of chromium measured for the uncoated steel and the steel/La0.6Sr0.4CoO3 layered system likewise indicates that the coating is capable of acting as an effective barrier against the formation of volatile compounds of chromium.

Research of the properties of the sandwich-structured Ni60CuMo self-lubricating coating with stepped hardness distribution on Vermicular cast iron by laser cladding

To enhance the wear resistance of Vermicular cast iron (RuT300) and achieve the stepped hardness distribution for the impact deformation resistance in the middle and lower part of the coating and wear resistance in the surface of the coating, the sandwich-structured Ni60CuMo coating with the transition layer was fabricated on RuT300 by laser cladding. The microstructure, hardness, and fracture toughness for the coating were analyzed, and the effect of different loads on wear resistance was investigated. The wear-resistant layer mainly contains Ni-based solid solution, hard phase of chromium compound and some ductile Cu phases. The hardness for coating without cracks shows the stepped distribution, increasing to 381HV0.5, 419HV0.5, and 490HV0.5 in the wear layer, transition layer, and heat-affected zone, respectively. The transition layer can suppress the impact of carbon from the substrate on the hardness of the wear-resistant layer. The wear resistance of the coating demonstrates a self-adaptive enhancement effect with increasing load. As the load increases from 10 N to 30 N and 50 N, the wear rate decreases from 2.865 to 1.525 and 1 (×10⁻⁴mm³N⁻¹m⁻¹). The main wear mechanism is oxidative wear. The extruded ductile Cu phase causes the wear debris to adhere it and the compacted oxide glaze layer is formed with the high load, then the compacted oxide glaze layer isolates oxygen and reduces oxidative wear. In contrast, incomplete oxide layers at low load fail to provide effective isolation, and cracks on the subsurface serve as critical pathways for continued oxygen penetration, resulting in more severe oxidative wear.

Thermal analysis of various chromium compounds using TGA and DSC methods: a comparative investigation

Thermal analysis of various chromium compounds using TGA and DSC methods: a comparative investigation

Assessing Trace Elements Bioaccumulation in Coastal River Fish and Shellfish: Implications for Human Health and Risk Evaluation.

The presence of heavy metal contaminants in fish and shellfish in aquatic environments poses a risk to human health due to trophic transfer. This study determined the levels of various trace elements (Fe, As, Cr, Zn, Cu, Ni, Pb, and Cd) in the muscles, gills, and liver of hilsa (Tenualosa ilisha) and prawn (Macrobrachium rosenbergii) samples obtained from the Tetulia River, Bangladesh. The results showed that the level of trace elements in different body parts differed significantly (P < 0.05) between species, displayed below recommended threshold levels. The cumulative low to higher hierarchic concentration of the trace elements was as follows: Fe > Zn > Cu > Cr > Ni > Pb > As > Cd. Hilsa had significantly (P < 0.05) higher bioaccumulated trace elements compared to prawn. With the exception of Ni and Cd, the estimated daily intakes (EDI) for both adults and children were below the recommended daily allowance (RDA), which exhibits that other trace elements do not cause harm to human health. Furthermore, the hazard index (HI) and total hazard quotient (THQ) were also found to be within acceptable limits, taking into account the higher vulnerability of children to toxicity compared to adults. Notably, the HI suggested that children were approximately four times more susceptible to both carcinogenic and non-carcinogenic effects compared to adults. Ultimately, the levels of carcinogenic risk were deemed acceptable, despite the estimated values suggesting susceptibility to adverse effects in both adults and children. This study concluded that fish and shellfish may not pose a health risk to consumers, highlighting the importance of further monitoring of trace elements in the catchment area.

Effects of Cr and Mo content on the microstructure and properties of Fe-based amorphous composite coatings by laser cladding

In this study, we successfully produced Fe-based amorphous composite coatings on the surface of 45 steel using laser cladding technology, and the impact of the relative content of Cr and Mo elements on the microstructure, hardness, and wear resistance of composite coatings has been investigated. The results show that the microstructure of the coating changes from dendrite to amorphous nanocrystalline when the content of Cr and Mo is 20 and 15 wt. %, respectively. However, when the Mo element continues to be added, elemental segregation will be caused, resulting in a large number of brittle Fe–Cr–Mo intermetallic compounds and MoSi2 ceramic phases in the coating. Therefore, the appropriate element ratio can not only increase the amorphous phase content in the coating but also prevent elemental segregation. Among the three types of amorphous composite coatings studied, the Fe45Cr20Mo15B10Si10 (wt. %) composite coating exhibited the most favorable performance, primarily due to its highest amorphous content (43.33%). Through the interaction of the amorphous phase, α-Fe, Fe–Cr solid solution, and a small proportion of intermetallic compounds, this coating achieved a hardness of 1282.8 HV0.2, approximately five times that of the 45 steel substrate, and demonstrated superior wear resistance.

Molecular beam epitaxy growth and doping modulation of topological semimetal NiTe2

In this study, high-quality thin films of the topological semimetal phase NiTe2 were prepared using the molecular beam epitaxy technique, confirmed through x-ray diffraction with pronounced Laue oscillations. Electrical transport experiments reveal that thick films have properties similar to bulk materials. By employing co-deposition, we introduced either magnetic or non-magnetic elements during the growth of thinner films, significantly altering their electrical properties. Notably, the magnetic element Cr induces long-range ferromagnetic ordering, leading to the observation of a significant anomalous Hall effect in NiTe2 thin films. The Hall conductivity remains nearly constant well below the Curie temperature, indicating the correlation with the intrinsic topological nature of the band structure. Theoretical first principles band calculations support the generation of the Weyl semimetal state in the material through magnetic doping. These findings pave the way for exploring more magnetic Weyl semimetals and related low-dimensional quantum devices based on topological semimetals.

GIS-based Visualization of Elemental Distribution in Neoboletus Luridiformis Fruiting Body.

The fruiting body of Neoboletus luridiformis (Scarletina bolete) mushroom was used to determine the level of bioconcentration and subsequent distribution of seventeen elements (Ag, Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Se, Sr, and Zn). A two-centimeter-thick vertical section of the entire fruit body was divided into 101 partial sub-samples where the contents of the studied elements were determined using ICP OES. The actual distribution of the elements in the fruiting body profile was visualized using a GIS interpolation method resulting in distribution maps. The study provides valuable insights into the distribution patterns of 17 elements within the fruiting body of N. luridiformis. Based on the visualization of the elemental content, the determined elements can be divided into three categories. Elements accumulated primarily (i) in the cap (Al, Ag, Ca, Cd, Cu, Fe, K, Mg, Ni, and Zn), (ii) in the stipe (Ba, Mn, Na, Pb, and Se), and (iii) elements with non-specific distribution (Cr and Sr). Since such detailed information supported by graphical visualization has not been published to date, the information in this study will help to better understand the accumulation and distribution of elements within the fruiting bodies of wild as well as cultivated mushroom species.

Investigating the Synergistic Corrosion Protection Effect of an Alloy Element and Corrosion Inhibitor on Steel Reinforcement Using Machine Learning and Electrochemical Impedance Spectroscopy

Steel reinforcement in marine concrete structures is vulnerable to chloride-induced corrosion, which compromises its structural integrity and durability. This study explores the combined effect of the alloying element Cr and the smart corrosion inhibitor LDH-NO2 on enhancing the corrosion resistance of steel reinforcement. Employing a machine learning approach with a support vector machine (SVM) algorithm, a predictive model was developed to estimate the polarization resistance of steel, considering Cr content, LDH-NO2 dosage, environmental pH, and chloride concentration. The model was rigorously trained and validated, demonstrating high accuracy, with a correlation coefficient exceeding 0.85. The findings reveal that the addition of Cr and application of LDH-NO2 synergistically improve corrosion resistance, with the model providing actionable insights for selecting effective corrosion protection methods in diverse concrete environments.

Enhancing strength and ductility in Fe–20Mn–9Al-1.5C austenitic low-density steels through Ni and Cr alloying synergy adding

In this investigation, a Fe–20Mn–9Al-1.5C lightweight austenitic steel has been developed through strategic alloying with Ni and Cr elements coupled with the employment of a thermo-mechanical processing technique featuring ultra-fast cooling. This composition and treatment synergistically transcend the conventional trade-off between strength and ductility, positioning the mechanical performance of this steel notably above that of comparable low-density austenitic steels previously reported. The coordinated incorporation of Ni and Cr is key to modulating the precipitation threshold for nanoscale κ-carbides and LRO domains, achieving an optimal size for precipitate-induced strengthening. The incorporation of Cr specifically contributes to a dual enhancement mechanism: it fosters the generation of high-density dislocation arrays (HDDA) and refines the dynamic slip band (DSBR) during deformation, which in turn, elevates the strain hardenability and ductility. The remarkable synergy in strength and ductility is attributed to a combination of mechanisms including grain boundary reinforcement, solid solution hardening, the precipitation strengthening effect of nanoscale precipitates, and the activation of secondary slip system dislocations. This synergy is quantitatively reflected in the material's yield strength (YS) exceeding 1100 MPa, ultimate tensile strength (UTS) surpassing 1200 MPa, and a total elongation (TEL) exceeding 45%. The insights gained from this research provide critical guidance for the design and creation of austenitic low-density steels that do not compromise between strength and ductility, thereby offering superior overall performance.

The comprehensive utilization of mass and heat of hot blast furnace slag and coordinated disposal of chromium-containing sludge to prepare glass-ceramic

Currently in steel enterprises, the mass and heat of hot blast furnace slag (BFS) are not fully recovered, and the produced chrome-containing sludge (CCS) poses a significant threat to the ecological environment. In this work, CCS together with other ingredients is added into hot BFS to produce high value-added glass-ceramic (GC), after the mixed molten slag is cooled down. The obtained GC shows excellent physical and chemical properties (bulk density: 2.76 g cm−3, water absorption: 0.059 %, compressive strength: 78 MPa, Vickers hardness: 7.54 GPa, acid resistance: 98.63 %, alkali resistance: 99.84 %, thermal conductivity: 1.049 W m−1 °C−1, and thermal expansivity: 6.56 × 10−6 m m−1 °C−1). These excellent physical and chemical properties render the as-prepared GC a high value-added building material. In addition, the leaching concentrations of total Cr element and Cr(VI) in the as-prepared GC are 1.6 mg L−1 and 1.03 mg L−1, respectively, which are below the standard threshold for hazardous waste extraction toxicity. Compared with the traditional sintering method, the sensible heat of the hot BFS can be used as the thermal source in the molten slag cooling method, which can save a lot of energy. The use of hot BFS and CCS to produce high value-added GC not only fully utilizes the mass and heat of hot BFS but also fixes the Cr element in the CCS within the crystalline phase of GC, thereby eliminating the pollution of CCS to the environment.

Trace Elements in Hermann's Tortoises (Testudo hermanni) According to Sex, Season, and Sampling Region in Central Europe.

Some trace elements are essential for the health of vertebrates, but little is known about their function, the amounts required, and the factors influencing their metabolism in tortoises. The aim of this study was therefore to measure trace elements (chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), selenium (Se), zinc (Zn)) in heparinized blood plasma of Hermann's tortoises (Testudo hermanni) (n = 520) from March to September 2022 using inductively coupled plasma mass spectrometry (ICP-MS) and to establish specific reference intervals. Additionally, the influence of sex, season, and region of sample collection on the measured values were evaluated. Significant (p ≤ 0.05) sex-specific differences were found for Cu, Mg, and Mn; seasonal differences were found for Cr, Cu, Mn, Mo, and Se; and the region in which the tortoises were kept significantly impacted Cr, Cu, Fe, Mg, Mo, and Se levels. The results show that all of these factors should be consider when establishing and interpreting blood trace element levels in tortoises.

Multi-Elemental Analysis of Edible Insects, Scorpions, and Tarantulas from French (Online) Market and Human Health Risk Assessment Due to Their Consumption: A Pilot Study.

Edible insects are becoming increasingly popular as protein alternatives to traditional animal-based products. As such, information on their elemental composition is important to ensure they are safe for human consumption. This article describes the development and validation of a rapid, reliable method for the simultaneous determination of 19 elements (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Pb, Se, Sr, and Zn) in edible insects by inductively coupled plasma mass spectrometry (ICP-MS) following closed vessel microwave digestion. The method was validated using three insect certified reference materials, namely black soldier fly larvae meal (BFLY-1), cricket flour (KRIK-1), and mealworm powder (VORM-1). The method was applied to analyze twelve different (whole) insect species. The maximum amount of each sample was calculated for As, Cd, and Pb with respect to their provisional tolerable daily intake values established by the Food and Agricultural Organization/World Health Organization. Most of the samples, except for scorpions and tarantulas, were safe to consume at large doses (1000-10,000 insects per day). Furthermore, most of the samples contained high levels of Fe, K, Na, and Zn, providing a preliminary overview of the nutritional profile of these novel protein alternatives.

Rapid qualitative and quantitative vital nutrient contents in high-altitude cultivated folklore herbal medicinal Costus roots using calibration-free LIBS

Costus Roots (CRs) (Saussurea lappa C.B. Clark- Asteraceae family) is a medicinal herb, very frequently utilized in developing countries for treating worm (nematode) infections, asthma, cholera, digestive problems and in cosmetics products. Due to its widespread consumption in developing countries to determine the health-related essential nutrients and toxic elements is of great significance. This study is highly noteworthy for prominence of therapeutic benefits of the CR roots and public awareness about their harmful effects even for producing herbal drugs derived from its roots. In this study, a very efficient, precise and rapid laser-induced breakdown spectroscopy (LIBS) method was developed to measure the content of the dried and pelletized CRs powder samples. To the best of our knowledge, this is first time that Costus roots have been studied using calibration-free LIBS (CF-LIBS) technique. Initially, the LIBS spectrometer parameters were optimized at 608.3 nm gated-time delay, 35 mJ incident laser pulse energy, and 29 mm laser-to-sample distance (LTSD)) for precise element detection before its application to the CRs analysis. The primary focus of this study is the identification and quantification of various nutrients, such as Ca, K, Mg, Si, S, P, Fe, and Na, as well as relatively toxic elements, such as Al, Ba, Mn, Zn, Sr, B, Cu, Rb, Cr, Ni, Pb, V, and Mo, in addition to Li, Ti in this native CRs herbal medicine. The concentrations of these detected elements (Ca, K, Mg, Si, S, P, Al, Fe, Na, Ti, Ba, Mn, Zn, Sr, B, Cu, Rb, Cr, Ni, Pb, V, Mo, and Li) were successfully determined as 14424, 9511, 2031, 1559, 1450, 1465, 678, 458, 59, 48, 47, 37, 37, 27, 19, 19.6, 15, 2.6, 1.5, 1.5, 1.2, 1.0 and 0.9 mg.kg−1 respectively which was in a excellent agreement with the concentrations measured using the standard ICP-OES technique.

RETRACTED: A semi-arid climate's use of exploratory data analysis (EDA) as a reliable non-parametric method for geochemical mapping

In this study, exploratory data analysis (EDA) methods, specifically boxplots, were employed to examine the composition of stream sediments in the Collo area of Northeast Algeria. The region's diverse lithological formations, interactions between permanent and temporary watercourses, intermittent flash floods, rugged topography, and fluctuating climatic conditions contribute significantly to data variability. Utilizing the boxplot's capabilities, our analytical approach successfully identified outliers, recorded the actual distribution of data, and determined skewness without the need for prior data processing, often required in conventional statistical studies. The boxplot proved to be an effective tool, offering insights into the geographical distribution of elemental concentrations, including iron (Fe), zinc (Zn), copper (Cu), arsenic (As), chromium (Cr), and lead (Pb). Geochemical mapping, driven by a robust class selection mechanism developed from the boxplot, revealed strong geographical correlations. A notable northeastern anomaly, characterized by elevated concentrations of Pb, Zn, Cu, and As, aligned with known base-metal sulfide and arsenopyrite mineralization sites. Additionally, outlier data for Cr indicated proximity to a plagioclase-lherzolite intrusion and known chromite deposits. The geographical distribution of iron, corresponding with known magnetite and hematite resources, was effectively highlighted using robust class selection based on boxplot analysis. This comprehensive investigation underscores the value of EDA methods in identifying mineralization trends amid the complex variability of the Collo area.

Middle Triassic Limestones as a Source of Trace Elements and REY.

The results of the content determination of the selected trace elements Ti, Sr, Ba, Zn, Pb, Cu, S, P, Cr, Cd, Ni, Zr, Mo, Rb, Sc, Y, and REEs were presented in this article. Studies were carried out to define the purity of limestones. The elements were measured in the carbonate minerals of Middle Triassic limestones of the Opole Silesia in Poland, using ICP-MS and X-ray fluorescence (XRF). Moreover, the contents of Sc and REY were also determined by electron microprobe analysis. These methods are characterized by high accuracy and precision of the measurement. The research results show that the contents of trace elements vary from below 1 ppm up to some hundreds ppm. The highest content was measured for strontium and the lowest for barium, elements characteristic of aragonite. Their occurrence indicates the presence of aragonite in the primary carbonate material. Some trace elements form substitutions in clay or carbonate minerals. Zn, Pb, Cu, Mo, and Ni may be associated with sulfides, and Ti and Cr may be associated with oxides. Sc and REY usually substitute Ca ions in calcite. The contents of measured Ce, Nd, Sm, Dy, Er, and Y vary from below 1 ppm up to 6 ppm, and Sc from 0 ppm to 10 ppm.

Microstructure, corrosion resistance and high temperature oxidation properties of AlCrFeNiCu high-entropy alloy coating by high-speed laser cladding

AlCrFeNiCu high-entropy alloy (HEA) coating was prepared on Zirconium (Zr) rod by high-speed laser cladding (HSLC) technique. The effect of different laser power and scanning speed on the forming quality of the coating was studied. When the specific energy density was in the range of 3.0–3.2 J/mm2, the AlCrFeNiCu HEA coating with good adhesion to the substrate, low dilution rate (small heat affected zone) and no cracks were obtained. The phase structure, microstructure, microhardness, corrosion resistance and high temperature oxidation resistance of the coating were tested and analyzed. The results show that the AlCrFeNiCu HEA coating is composed of 76.9 % BCC phase and 23.1 % FCC phase, in which the BCC phase is mainly composed of disordered BCC phase rich in Cr and Fe elements and ordered B2 phase rich in Al and Ni elements, and the FCC phase is rich in Cu elements. Due to the rapid cooling of HSLC, the coating structure gradually changes from columnar crystal to equiaxial crystal from bottom to top. The hardness of the coating is as high as 805 HV, which may be caused by the solution strengthening effect, lattice distortion effect and slow diffusion effect of HEA. In 3.5 % NaCl solution and 0.1 mol/L KOH solution, the self-corrosion current density of the coating is 4.209 × 10−8 A/cm2 and 4.331 × 10−8 A/cm2, respectively. The passivation film on the surface of the coating is composed of a variety of oxides, and the oxygen vacancy density of the passivation film in the two solutions is 2.552 × 1020 cm−3 and 5.794 × 1020 cm−3, with fewer pitting pits on the surface. The structural integrity of the coating can be maintained after 60 min oxidation at 1200 °C. The oxidation process follows the growth kinetics curve, and the surface oxides mainly comprise FeAl2O4, Al2O3 and Cr2O3. AlCrFeNiCu HEA coating improves the corrosion resistance and high temperature oxidation resistance of the Zr-4 alloy.