Chromate Resistance Research Articles

A stable high-entropy perovskite La0.2Pr0.2Nd0.2Sm0.2Sr0.2Co0.8Fe0.2O3-δ oxygen electrode for reversible solid oxide cells

The electrocatalytic performance of oxygen electrode materials is one of the core issues limiting the development of reversible solid oxide cell (RSOC). In this work, the high-entropy perovskite material La0.2Pr0.2Nd0.2Sm0.2Sr0.2Co0.8Fe0.2O3-δ (HE-LSCF) is synthesized and the catalytic performance is systematically investigated. At 800 ℃, the polarization impedance (Rp) of HE-LSCF cathode is 0.19 Ω·cm2, exhibiting excellent catalytic activity. HE-LSCF exhibits excellent chromium resistance by the doping of highly acidity cations, with the Rp only increased to 3.23 Ω·cm2 after the stability test. In addition, with HE-LSCF electrode on RSOC, the Rp was 0.15 Ω·cm2 at 800 ℃. Meanwhile, with the electrolysis voltage of 1.6 V, the current density is up to −738 mA/cm2. Moreover, the performance of the cell shows no significant degradation in the reversible cycling test, showing an excellent stability brought by the high-entropy design. Through the study, HE-LSCF is proved to be a promising oxygen electrode material.

Effect of bias voltage on high-temperature oxidation resistance and electrical properties of Mn–Co coating with metal interconnects for solid oxide fuel cell

Abstract This study investigated the effects of bias voltage on the microstructure, high-temperature oxidation resistance, electrical conductivity, element diffusion, and barrier of chromium poisoning cathode of Mn–Co coating on the surface of SOFCs metal interconnect SUS441 ferritic stainless steel. A series of Mn–Co coatings were prepared by magnetron sputtering technique at different bias voltages (−10, −50, −90 V) and oxidized at high temperatures for 175 h at 850 °C in an air environment. The results showed that the surface of each coating before oxidation exhibited a cauliflower-like morphology, with the crystallinity of the coating increasing with higher bias voltage. After high-temperature oxidation, especially the Mn–Co coatings prepared at −90 V bias, a dense and stable MnCo2O4 spinel structure was formed, which is crucial in inhibiting the growth of the Cr2O3 oxide layer. In addition, the coating also exhibits excellent electrical conductivity (Ea = 0.35 eV), good high-temperature oxidation resistance (1.182 mg cm−2), and a stronger ability to prevent the diffusion of Cr elements.

An active and Cr-tolerant high-entropy La0.7Sr0.3FeO3-δ based cathode for solid oxide fuel cells

The development of high active and stable cathode materials is one of the main challenges of intermediate temperature solid oxide fuel cells (SOFCs). Herein, a high-entropy Fe-based perovskite oxide La0.7Sr0.3Fe0.3Ni0.3Co0.3Mo0.1O3-δ (LSFNCM) is synthesized by self-propagation combustion based on La0.7Sr0.3FeO3-δ (LSF) and the electrochemical properties are systematically tested. The symmetric half-cell with the LSFNCM cathode has a high catalytic activity with a polarization impedance of 0.12 Ω cm2 at 800 °C, and also shows outstanding CO2 resistance and chromium resistance owing to the entropy stabilization strategy. After 50h of treatment in a 10% CO2 environment, the polarization impedance of the LSF electrode increases by 8.89 Ω cm2, while that of the LSFNCM electrode only increases by 1.81 Ω cm2. Additionally, after being treated for 24h in a chromium vapor environment, the polarization impedance of the LSF electrode increases by 5.95 Ω cm2, whereas that of the LSFNCM electrode only increases by 0.44 Ω cm2. Moreover, the single cell with LSFNCM cathode exhibits the maximum power density of 932.82 mW/cm2 and the polarization impedance of 0.34 Ω cm2 at 800 °C with humidify hydrogen as fuel. Our results indicate that high-entropy perovskite oxide LSFNCM is an active and Cr-tolerant promising cathode for SOFCs.

Shotgun metagenomic analysis reveals the emergence of plasmid-encoded mcr-5.1 gene in hospital wastewater in Bangladesh

Colistin is considered the last line therapy for treating multidrug-resistant (MDR) bacterial infections in humans. Therefore, the spread of colistin resistance poses a serious threat to human, and environmental health. Though Bangladesh is known as a hotspot of AMR, limited studies have been carried out regarding the status of colistin resistance. Information on the emerging bacterial resistance is inevitable for protecting public health. Nowadays, wastewater analysis has been prioritized for metagenomics-enabled AMR surveillance. Our study on the metagenomic analysis of untreated hospital effluents first detected the colistin resistance-conferring mcr-5.1 gene in the hospital environment of Bangladesh. Phylogenetic tree and in silico AMR analysis confirmed the detection of this mcr-5 variant, which is located in a plasmid contig. The plasmid was untypeable and belonged to the bacteria from the Enterobacteriaceae family. The mcr-5.1 operon was embedded in a Tn3 transposon, suggesting the mobility of the gene. Tnshfr1 transposon, chromate resistance protein ChrB, DNA invertase hin, and two MFS-type proteins were present in the genetic environment of mcr-5.1. Our findings provide evidence of the occurrence of mcr-5.1 in a hospital environment in Bangladesh, which calls for immediate attention and effective measures to contain the dissemination of colistin resistance in the environment.

Enhancing chromium resistance and bulb quality in onion (Allium cepa L.) through copper nanoparticles and possible health risk

Chromium (Cr) is a toxic metal in soil–plant system, hence causing possible health risks prominently in the areas with forgoing industrial activities. Copper nanoparticles (Cu NPs) have been reported as an excellent adsorbent for pollutants. Therefore, this study investigates how copper nanoparticles enhance onion growth while decreasing chromium uptake in onion plants. Additionally, it examines the potential health risks of consuming onion plants with elevated chromium levels. The results demonstrated that the addition of CuNPs at 15 mg kg−1 significantly improved the plant height (48%), leaf length (37%), fresh weight of root (61%), root dry weight (70%), fresh weight of bulb (52%), bulb dry weight (59%), leaves fresh weight (52%) and dry weight of leaves (59%), leaf area (72%), number of onion leaves per plant (60%), Chl. a (42%), chl. b (36%), carotenoids (40%), total chlorophyll (40%), chlorophyll contents SPAD value (56%), relative water contents (35%), membrane stability index (16%), total sugars (25%), crude protein (21%), ascorbic acid (19%) and ash contents (64%) at 10 mg kg−1 Cr. Whereas, maximum decline of Cr by 46% in roots, 68% in leaves and 92% in bulb was found with application of 15 mg kg−1 of Cu NPs in onion plants under 10 mg kg−1 Cr toxicity. The health risk assessment parameters of onion plants showed minimum values 0.0028 for average daily intake (ADI), 0.001911 for Non-cancer risk (NCR), and 0.001433 for cancer risk (CR) in plants treated with Cu NPs at 15 mg kg−1 concentration grown in soil spiked with 10 mg kg−1 chromium. It is concluded that Cu NPs at 15 mg kg−1 concentration improved growth of plants in control as well as Cr contaminated soil. Therefore, use of Cu NPs at 15 mg kg−1 concentration is recommended for improving growth of plants under normal and metal contaminated soils.

Harnessing the chromium reduction potential of Pseudomonas aeruginosa JRHM33: A comprehensive study on bioinformatics, phenotype microarray, and CCD-RSM optimization

Large amounts of wastewater are generated due to overpopulation and industrialization, The bioavailability, toxicity, and permanence of metals make heavy metal contamination a big environmental hazard. In order to maximize chromium (Cr+6) removal efficiency, the current investigation was carried out from industrial wastewater using Pseudomonas aeruginosa JRHM33.35 bacterial strains were discovered based on their physical, and biochemical properties and resistance towards chromium (Cr+6) heavy metal. The most significant bacterial strain JRHM33 found the highest-level of 1000 mg/L of chromium (Cr+6) resistance. The bacterial strain JRHM33, which has 99 % similarity to Pseudomonas aeruginosa, was found using 16 S rRNA sequencing and is employed in subsequent steps. Sequencing and study of conserved domains indicate that JRHM33 contains the laccase gene and belongs to the multicopper oxidase superfamily, which is known for its ability to reduce metal ions. Analysing phenotype microarray (PM) technology sheds light on Pseudomonas aeruginosa JRHM33 metabolic profile of microbial cells. Additionally, a series of process parameter optimizations were tried using the central composite design of response surface methodology (CCD-RSM) in an effort to reduce the amount of chromium (Cr+6) in the effluent as much as possible. At 6.8 pH, 90 min of incubation, inoculum size is 3.8 ml, and agitation is 104 rpm, a maximum 71 % Cr+6 reduction was attained. The model constructed has an R2 score of 0.983 indicates a very statistically significant outcome from the analysis of variance. The experimental outcomes and the predicted results were remarkably similar, according to the validation experiment. Studies have revealed that bacterial strains obtained from effluent containing high levels of metals utilize their inherent capability to change harmful heavy metals into less dangerous or harmless forms.

Enhancement, application, and challenges of chromium–corundum high‐temperature refractories

AbstractChromium–corundum, as a common refractory material, is broadly applied in high‐temperature kilns due to its superior thermal stability and high melting point. Unfortunately, this refractory is susceptible to corrosion and destruction under extreme furnace conditions by chemical erosion, mechanical wear, and thermal shock, which significantly shortens its useful life. Accordingly, in recent years, the issue of how to improve the slag corrosion resistance, mechanical, and sintering properties of chromium–corundum refractories has aroused widespread attention. In this work, the corrosion behavior and application status of chromium–corundum refractories in Ausmelt furnace, waste incinerator, coal water slurry gasifier, and HImelt melting reduction furnace are analyzed and discussed. To improve the service life of chromium–corundum refractories, the enhancement method and mechanism of sintering performance, mechanical properties, slag corrosion resistance, and thermal shock resistance are also summarized. Finally, some suggestions and prospects are made for the enhancement and longevity of chromium–corundum refractories.

Effect of carbide refinement on high temperature erosive wear behavior of high chromium white cast iron with different titanium and carbon additions

It is known that better erosion wear resistance of high chromium (27 wt% Cr) white cast iron (HWCI) with titanium (Ti) addition can be achieved by controlling the size of M7C3 carbides. Nevertheless, it might not be directly applicable to high temperature conditions due to the more complex factors involved, especially the hot oxidation behavior. Therefore, the effect of 0–2 wt% Ti and 3–4 wt% carbon (C) addition on the high temperature erosion wear behavior of HWCI has been investigated in this research. The results show that there are TiC and M7C3 carbides precipitated in the material matrix. The size of M7C3 carbides decreases drastically as the amount of Ti increases. On the contrary, it is effectively enlarged with the addition of higher C. In addition, there is no significant difference in hardness among all specimens due to the relatively similar carbide volume fraction (CVF). The wear resistance of HWCI is improved by increasing the amount of Ti although it has a lower value as the C content increases. It means that hardness is not an important factor in evaluating the wear characteristics of HWCI at high temperatures. The worn surfaces and cross-sections show that the smaller M7C3 carbides are more likely to undergo plastic deformation rather than being directly peeled out. In addition, the effect of hot oxidation behavior was negligible because there is only a very thin oxidation layer on the worn surface. Therefore, it can be concluded that the erosive wear behavior of the material is greatly influenced by the size of M7C3, which the material with better erosive wear resistance contains finer carbides.

Corrosion resistance of chromium coating on the inner surface of EP823-Sh steel cladding

The processes of corrosion damage of the inner surface of the cladding are determined by corrosive reagents aggressive with respect to the cladding and the type of fuel used. Reactor irradiation of cladding made of EP823-Sh steel with mixed nitride fuel planned for use in the BREST-OD-300 reactor revealed non-uniform corrosion of the inner surface of the cladding. In this paper, the use of the chromium coating is proposed to prevent the corrosion of the inner surface of the steel fuel cladding. The results of corrosion tests of chromium coating applied to the inner surface of cladding made of EP823-Sh steel by electrolytic deposition are presented. Electron-microscopic studies of the chromium coating on EP823-Sh steel showed no significant signs of corrosion damage when tested in the environment of simulant fission products (CsI+Te) and in liquid lead at 650 °C.

Super hardening of Fe[sbnd]W alloy plating by phase transformation of amorphous to metal carbides-dispersed nanocrystalline alloys and application as promising alternative for hard chromium plating

Despite the superior hardness, wear resistance, and corrosion resistance of hard chromium (Cr) plating using toxic hexavalent chromium (Cr6+), the gradual restriction on the use of Cr6+ in industrial fields necessitates the development of an alternative, harmless plating material with excellent performance. Here, we report the fabrication of super-hard plating by the simple annealing of electrodeposited FeWC plating as a promising alternative for hard Cr plating. Amorphous-structured FeWC plating, including co-deposited citric acid-derived carbon, forms uniformly dispersed ternary metal carbides inside the plating during annealing, which changes the plating structure from amorphous to nano-carbide-dispersed alloys. The phase-transformed, nanocrystalline FeWC alloy annealed at 700 °C exhibited a maximum hardness of 20.5 GPa, which surpassed the hardness of hard Cr plating (12.5 GPa). The ball-on-disc tribo-test and corrosion test results further demonstrated the superior wear and anti-corrosion properties of the carbide-dispersed FeWC alloy plating compared with hard Cr plating. This study develops the applicability of this super-hard plating as a new hard coating material that overcomes the limitations of conventional metal plating without using any toxic chemical.

Preliminary Study on Screening and Genetic Characterization of Lactic Acid Bacteria Strains with Cadmium, Lead, and Chromium Removal Potentials

Due to industrial development, heavy metal pollution has become a severe global health hazard. The bioadsorption method represented by the adsorption of lactic acid bacteria (LAB) has been widely employed. The purpose of this study is to screen LAB strains that can remove cadmium, lead, and chromium. Through the heavy metal resistance tests, four strains with significant growth inhibition rate were identified. After 16S rDNA sequencing, these resistant strains were identified by Lactobacillus helveticus KD-3 (Cd2+ removal rate 37.54 ± 0.85%), Limosilactobacillus fermentum B27 (Pb2+ removal rate 69.41 ± 0.19%), Lacticaseibacillus rhamnosus 7469 (Cr6+ removal rate 71.13 ± 0.97%), and Lb. helveticus K5. Three encoding genes were identified in our screen strains, namely resistance gene czcD, chromium resistance gene chrA, and lead resistance gene pbrT. L.helveticus KD-3 exhibited the best comprehensive performance. Given the diverse types of heavy metal pollution at present, the current research mainly focuses on the removal of a single heavy metal by one strain. The four strains enrich the absorption resources of LAB for heavy metals, paving a new way for the biosorption of various heavy metals in food by LABs.

Polymer-derived SiAlOC coating to improve the high-temperature resistance of chromium

Cr and its alloys are interesting materials for applications at temperatures higher than 1000 °C. However, challenges such as limited oxidation resistance and nitridation still restrict their usage as high-temperature structural materials. The present work investigates the influence of a 0.6 μm thin SiAlOC sol-gel coating on the oxidation resistance and kinetic of Cr at 950 °C for 50 h and 1050 °C for up to 100 h of exposure time in dry synthetic air using thermogravimetric analysis. The resulting oxide scale and microstructure were extensively studied by combining different techniques such as EPMA, XRD, SEM, Raman spectroscopy, FT-IR, and STEM. Overall, a reduction in mass gain and an improved scale adhesion was observed. The interaction of coating and substrate causing nanosized Cr2O3 and cristobalite formation in the SiAlOC coating was further supported by investigations of bulk materials.

Integrative application of biochar and arbuscular mycorrhizal fungi for enhanced chromium resistance in Medicago sativa

Soil chromium (Cr) contamination has become an environmental problem of global concern. However, the joint effects of combined utilization of biochar and arbuscular mycorrhizal (AM) fungal inoculum, which are considered as two promising remediation strategies of soil heavy metal pollutions, on plant Cr resistance are still poorly understood. In this study, a two-factor pot experiment was conducted to investigate how biochar and AM fungus Rhizophagus irregularis regulate Medicago sativa growth, physiological trait, nutrient and Cr uptake, relevant gene expressions, soil properties, and Cr speciation, independently or synergistically. The results showed that biochar notably decreased AM colonization, while biochar and AM fungus could simultaneously increase plant dry biomass. The greatest growth promotion was observed in mycorrhizal shoots at the highest biochar level (50 g kg−1 soil) by 91 times. Both biochar application and AM fungal inoculation enhanced plant photosynthesis and P nutrition, but the promoting effects of AM fungus on them were significantly greater than that of biochar. In addition, the combined application of biochar and AM fungus dramatically reduced shoot and root Cr concentrations by up to 92 % and 78 %, respectively, compared to the non-amended treatment. Meanwhile, down-regulated expressions were observed for metal chelating-related genes. Furthermore, Cr translocation from roots to shoots was reduced by both two soil amendments. Transcriptional levels of genes involved in reactive oxygen species and proline metabolisms were also regulated by biochar application and AM fungal colonization, leading to alleviation of Cr phytotoxicity. Furthermore, AM fungal inoculation slightly elevated soil pH but decreased plant-available soil P, which was, by contrast, lifted by biochar addition. The combined application reduced soil acid-extractable Cr concentration by 40 %. This study provides new insights into comprehensively understanding of the mechanisms of biochar and AM fungi combination on improving plant Cr tolerance.

Effect of current density on the texture, residual stress, microhardness and corrosion resistance of electrodeposited chromium coating

Textures and residual stresses are generated during electrodeposition of chromium coatings, which directly affect the performance of the coating. In this work, the variations of texture, hydrogen content, residual stress, microhardness and corrosion resistance of chromium deposited from hexavalent [Cr(VI)] chromium bath using direct current deposited technique were investigated. Electrodeposition experiments were carried out on the low carbon steel substrate by varying the key variable current density. The macrotexture of the coatings was studied by XRD. The crystal orientation and dislocation density were analyzed by EBSD. Residual stress was measured by the indentation method. The research demonstrated that a single preferred orientation on the (222) plane was found at current densities of 20 A/dm2, 35 A/dm2 and 50 A/dm2. At 40 A/dm2, a mixed preferred orientation on the (222) + (211) planes was discovered. Furthermore, the formation of the chromium coating texture was affected by the variation of hydrogen content, for higher hydrogen promoting grain growth along the (222) crystal plane. Notably, the microstructure-property relationship was developed. At the single preferred orientation of (222) plane, the corrosion resistance was more favorable. At the mixed preferred orientation of (222) + (211) planes, the coating surface achieved higher microhardness, but formed higher residual stress and more microcracks. Moreover, the better electroplating parameter was proposed. At 35 A/dm2, the coating had the fewer microcracks and the better overall performance. The higher microhardness of 753 HV was found. The more favorable corrosion resistance was discovered, with the breakdown potential and passive current density of 804.7 mV and 2.220 × 10−6 A/dm2. The lower residual stress of 61 MPa was found, which was about 81 % lower than the maximum stress. It was significant in industry for the enhancement of the service life of substrate and the optimization of the chromium coating process.

Correlating numerical modelling with experimental studies to quantify the wear resistance of high-carbon chromium bearing steel in mixed lubrication

High-carbon chromium steel is a main material to make bearings, owing to the notable wear resistance. However, researches on the abradability of this material in mixed lubrication are rarely available. Therefore, an approach by combining mixed lubrication simulation and ball-disc wear experiment was proposed to determine the correlation between oil film parameter and wear coefficient of GCr15 (AISI52100) bearing steel. Generous of ball-disc wear experiments were conducted under varied lubrication conditions to obtain matching wear coefficient. In terms of the simulations and experiments, the relationship between oil film parameter and wear coefficient was quantified. Furthermore, the analysis of the variation of wear coefficient with the factors in operating conditions demonstrated that the normal load and rotation velocity significantly affects wear coefficient.

Whole-genome sequencing of biofilm-forming and chromium-resistant mangrove fungus Aspergillus niger BSC-1

Filamentous fungus Aspergillus niger has gained significant industrial and ecological value due to its great potential in enzymatic activities. The present study reports the complete genome sequence of A. niger BSC-1 which was isolated from Indian Sundarban mangrove ecosystem. The study revealed that the genome of A. niger BSC-1 was 35.1 Mbp assembled in 40 scaffolds with 49.2% GC content. A total of 10,709 genes were reported out of which 10,535 genes were predicted for encoding the proteins. BUSCO assessment showed 98.6% of genome completeness indicating high quality genome sequencing. The genome sequencing of A. niger BSC-1 revealed the presence of rodA and exgA genes for initial adhesion to surface and Ags genes for matrix formation, during biofilm growth. OrthoVenn2 analysis revealed that A.niger BSC-1 shared 9552 gene clusters with the reference strain A. niger CBS554.65. Semi-quantitative RT-PCR analysis unveiled the role of Ags1 and P-type ATPase in fungal biofilm formation and chromium (Cr) resistance, respectively. During biofilm growth the expression of Ags1 significantly (P < 0.0001; two-way ANOVA followed by Sidak's multiple comparisons test) increased with respect to planktonic culture revealing the possible involvement of Ags1 in biofilm matrix formation. Expression of P-type ATPase gene was significantly upregulated (P < 0.0001; one-way ANOVA followed by Dunnett's multiple comparisons test) with the increasing chromium concentration in the fungal culture. Besides, several other genes encoding metalloprotease, copper and zinc binding proteins, and NADH-dependent oxidoreductase were also found in the genome of A. niger BSC-1. These proteins are also involved in heavy metal tolerance and nanofabrication indicating that this filamentous fungus A. niger BSC-1 could be potentially utilized for chromium detoxification through biofilm or nanobiremediation.

A medium entropy cathode with enhanced chromium resistance for solid oxide fuel cells

Perovskite type SrCo0.9Ta0.1O3-δ (SCT91) cathode exhibits high activity for oxygen reduction reactions, but the instability in Cr-containing atmosphere restricts its application in intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, a B-site medium-entropy SrCo0.5Fe0.2Ti0.1Ta0.1Nb0.1O3-δ (SCFTTN52111) cathode is proposed and investigated as a potential Cr-tolerance cathode. The electrochemical activity of pristine SCT91 cathode degrades rapidly in the presence of volatile chromium species. In contrast, SCFTTN52111 performs very stable. Chromium vapors prefer to react with segregated SrO species rather than Co3O4 precipitates. Significant secondary phases of SrCrO4 and Co3O4 are detected on SCT91 electrode, while only trace by-products are found on medium-entropy cathode. The better Cr tolerance is closely related to the enhanced structural stability by medium-entropy engineering and reduced surface Sr segregations. This work sheds light on the development of robust cathodes for IT-SOFCs through rational design of configuration entropy.

Effect of chromium coating roughness and thickness on interfacial heat transfer behaviour of sub-rapid solidification process

ABSTRACT The comparisons of wear resistance and heat transfer behaviours of chromium and brass were conducted. The effects of different values of chromium coating average roughness (1.240, 4.576, 7.388, 9.323 μm) and thickness (15, 35, 55 μm) on the interfacial heat transfer behaviours were investigated with a novel droplet solidification technique. The results revealed that, compared with the brass, the chromium material has a significant improvement in the Vickers hardness and wear performance and a reduction of 25 percent interfacial heat transfer rate. Moreover, with the increase of the coating average roughness from 1.240 to 7.388 μm, the maximum heat flux between molten steel and cooling substrate decreases from 8.27 to 5.56 MW/m2 due to the enlargement of the air gap. As the coating average roughness further increases to 9.323 μm, the maximum heat flux increases to 6.50 MW/m2 because of the increasing contact area between molten steel and the cooling substrate. In addition, the maximum heat flux was reduced from 8.47 to 5.87 MW/m2, considering the enhancement of interfacial thermal resistance when the coating thickness increases from 15 to 55 μm. The results obtained have important implications for heat transfer control of the strip casting process by adjusting the coating average roughness and thickness.

High-temperature oxidation of zirconium alloys with magnetron sputtered chromium coatings

Loss-of-coolant accidents (LOCAs) often lead to dire consequences. That&rsquo;s why the global community are actively engaged in research aimed at creating accident tolerant fuels. One of the areas of such research is preserving zirconium alloys as the material for fuel-element claddings by creating corrosion-resistant coatings that would be in contact with the coolant. Chromium could be a promising material to be used in such protective coatings as chromium oxide (Cr2O3) serves as an effective barrier for oxygen both in normal operation and in case of LOCA. Chromium coating hinders oxygen diffusion into the metal substrate and thus prevents embrittlement and failure of the fuel-element cladding. This paper describes the results of research studies that have been carried out in recent years and that look at the resistance of magnetron sputtered chromium coatings to high-temperature oxidation in water vapour up to 1,500 oC. The paper demonstrates advantages and drawbacks of chromium coatings in hightemperature oxidation conditions. The focus is on understanding how regimes of magnetron sputtering influence the resistance of chromium coatings to high-temperature oxidation and how the structure and phase state of chromium coatings are related to their properties. The authors describe the optimal regimes of magnetron sputtering for obtaining dense coatings and examine the effect of the substrate temperature and the bias voltage on the structure and density of resulting coatings. High Power Impulse Magnetron Sputtering (HiPIMS) serves as an effective technique that helps enhance the density of coatings. The conclusion drawn is that in order to broaden the temperature range in which chromium coatings can effectively protect zirconium alloys from failure up to 1500 oC, there should be a diffusion barrier between the surface of the fuel-element cladding and the chromium coating. The authors would like to thank B. A. Kalin, supervisor of this project, who had passed away before this publication was made. The staff of the Laboratory of Ion-Plasma and Ion-Beam Machining of Materials, a part of Department No. 9 at the National Research Nuclear University MEPhI, devote this paper to his memory.

Comprehensive evaluation on gamma radiation resistance of chromium (III) ions incorporated bismuth fluoro-lead-borate glasses

Gamma-ray shielding properties of high dense glassy system (bismuth fluoro-lead-borate doped with chromium (III) ions) with composition of (25-x)PbF2–25Bi2O3–49.8B2O3–0.2Cr2O3- xCaF2- (where x = 0 (S1), 5 (S2), 10 (S3), 15 (S4), 20 (S5), and 25 (S6) mol%) have been investigated. Phy-X/PSD software was used to achieve this purpose in photon energy range (0.15–15 MeV). Additionally, the superior glass shield sample was compared to several types of glass and concrete shields. Results revealed that each photon energy value investigated the maximum linear attenuation coefficient (µm) values for the S1 glass sample with the heaviest element contribution in its structure were detected at the maximum level. In terms of the µm, there was a difference of roughly 0.5 cm2/g in the S1 and S6 glasses. The S1 sample with the highest µm also had the lowest T0.5 and mean free path (λ). The heavy element contribution to the S1 sample was reflected in the effective atomic number values, which provided the S1 sample with the highest Zeff values. Values of exposure and energy absorption buildup factors (EBF and EABF) were confirmed that the sample S1 has the minimum values. Our findings showed that S1 sample may be considered as superior gamma-ray shielding properties among all studied glasses.