Iron Chromium Research Articles

The Structure and Properties of 65 wt.% Fe–35 wt.% FKh800 Chromium Carbide Steel Doped with Titanium Boride Additions

The effect of TiB2 additions on the structure, phase composition, and mechanical and tribological properties of materials in the Fe–FKh800 system was studied. The introduction of titanium boride additions activated compaction of the iron-based composites through sintering with participation of the liquid phase that emerged with the formation of low-melting Fe–C–B (Tm ~ 1050°C) and γ-Fe–Fe2B–TiB2 (Tm ~ 1162) eutectics and led to a 50–70°C decrease in the sintering temperature of the compacts. Titanium boride additions between 0.38 to 0.74 wt.% provided 20–25% higher bending strength of the 65 wt.% Fe–35 wt.% FKh800 composite with a slight increase in hardness. Metallographic studies, X-ray diffraction, and electron microprobe analysis of the Fe–35 wt.% FKh800–TiB2 materials showed that titanium boride additions promoted a multiphase, microheterogeneous matrix-reinforced composite, consisting of Kh17 chromium steel, double M7C3 and M3C iron–chromium carbides, and complex Me3(CB) carboborides. The influence of TiB2 additions on the wear resistance of the composites subjected to dry friction against fixed diamond wheel particles and ShKh15 steel was studied. The study showed that the abrasive mass wear (Im) of carbide steels decreased from 36.94 to 14.8 mg/km and their linear wear (Il) decreased from 0.197 to 0.079 mm/km with TiB2 additions increasing from 0.38 to 1.48 wt.%. Titanium boride additions ranging from 0.38 to 2.2 wt.% reduced the mass wear rate from 4.9 to 1.9 mg/km in dry friction of the composite against a ShKh15 steel counterface with 50–55 HRC hardness and decreased the friction coefficient from 0.49 to 0.38.

Synthesis of flower-like nickel–iron–chromium nanostructure compound deposited stainless steel foil as an efficient binder-free electrocatalyst for water splitting

A flexible NICC/SSF electrode with a flower-like nanostructure as a bifunctional electrocatalyst exhibits favorable catalytic activity in both the HER and OER for overall water splitting.

Сучасний екологічний стан поверхневих вод р. Трубіж

The problem of environmental safety of water bodies is relevant today, especially for the basins of small and medium-sized rivers, which are clear indicators of the environment state. One of them is the Trubizh River. The water resources of this river are formed under the anthropogenically changed conditions of the drainage and humidification complex of the Trubizh reclamation system. These resources are also receivers of effluents from point and diffuse sources. Thus, there is a need for constant monitoring of the ecological condition of the river. The water quality of it is a consequence of anthropogenic activities in the watershed. The aim of the work is a comprehensive assessment of the Trubizh River ecological condition under the modern conditions of water quality formation. The analysis has been conducted using official data from the state monitoring of water quality for 2015-2019 years and our own research for 2015-2016 years. 7 observation points have been considered from souse to mouth of the river: border areas of Brovary and Baryshivka; Baryshivka – 1 km above and 0.9 km below the village, Pereyaslav-Khmelnytsky – 0.5 km above and 1 km below the town, the mouth of the Alta and Trubizh rivers). We used such methods as analytical (determination of water quality indicators according to generally accepted standardized methods); analysis, systematization and generalization of the monitoring database; method of calculation of integrated block indices and complex ecological index of water quality (IE). It is established that during the five-year period (2015-2019) according to the weighted average and the worst values of the complex ecological index (IEworst 4.2) the waters are characterized as "satisfactory", "slightly polluted" of the III class quality 4 category. In 2018 and 2019 years, there was a deterioration in water quality by one category (III quality class 5 category) - "mediocre", "moderately polluted" water. This is due to a set of conditions of natural and climatic (insufficient rainfall and rising air temperature) and anthropogenic nature (water pollution, unauthorized surface water abstraction, runoff obstruction, etc.). It is noted that Trubizh river is characterized by stable uniform spatial water pollution. The largest values of IE are recorded in the area of influence of the village Baryshivka (IE worst 3.7-3.8) and Pereyaslav-Khmelnytskyi in the sampling points: the Alta river mouth (IEworst 4.0) and the Trubizh river mouth (IEworst 3.7). The water quality in these sampling points corresponded to class III of category 4 and was generally characterized as "satisfactory", "polluted". In general, the deterioration of water quality is caused by organic pollution (according to the indicator of dichromate oxidation (IV class, 6 category), BOD5 (Biochemical oxygen demand) (III class, 5 category), nitrogen compounds (ammonium, nitrite and nitrate) – V class, 7 category) and phosphorus compounds (phosphate ions – III class, 5 category), total iron and general chromium – III class, 5 category, phenols and SSAS (synthetic surfactants active substances) – IV class, 6 category. Thus, one of the main reasons for the degradation of the river is the anthropogenic conditionality of its development as a result of the urbanized and agricultural areas impact. The obtained data open the prospect of continuing work on monitoring and assessing the ecological status of aquatic ecosystems of the Trubizh River for the further development of scientifically based recommendations. It is necessary for making management decisions for sustainable use and protection of surface waters and restoration of aquatic ecosystems of Trubizh River Basin.

Excellent stability and electrochemical performance of the electrolyte with indium ion for iron–chromium flow battery

Iron–chromium flow battery (ICFB) is one of the most promising technologies for energy storage systems, while the parasitic hydrogen evolution reaction (HER) during the negative process remains a critical issue for the long-term operation. To solve this issue, In3+ is firstly used as the additive to improve the stability and performance of ICFB. The results suggest that In3+ not only effectively inhibits the HER but also accelerates the kinetics of Cr3+/Cr2+ and Fe3+/Fe2+ to some extent. More importantly, the ICFB using an optimal concentration of 0.01 M In3+ in the anolyte exhibits an energy efficiency of 77.0% at 200 mA cm−2, and a 36.3% higher capacity retention ratio than that of the pristine anolyte after 140 cycles at 160 mA cm−2. Furthermore, the capacity decay rate is low to 0.16% per cycle during the cycle test, which is much lower than that in the previous studies. Both the enhanced stability and electrochemical performance are attributed to the coupling effect of the inhibited HER and promoted kinetics of Cr3+/Cr2+ after In3+ is introduced. Therefore, In3+ as an anolyte additive can be a promising and cost-effective method to further improve the battery performance of ICFB and promote its engineering application.

High-performance bifunctional electrocatalyst for iron-chromium redox flow batteries

Despite a variety of advantages over the presently dominant vanadium redox flow batteries, the commercialization of iron–chromium redox flow batteries (ICRFBs) is hindered by sluggish Cr2+/Cr3+ redox reactions and vulnerability to the hydrogen evolution reaction (HER). To address these issues, here, we report a promising electrocatalyst comprising Ketjenblack (KB) carbon with embedded bismuth nanoparticles (Bi-C). The uniform incorporation of Bi nanoparticles into KB carbon via a simple reduction process excellently promotes the electrochemical activity of Cr2+/Cr3+ redox reactions while retarding the HER. A combination of experimental analysis and density functional theory (DFT) calculations indicates that these phenomena are attributable to the synergistic effect of Bi and KB, which inhibits hydrogen evolution and provides active sites to enhance the Cr2+/Cr3+ redox reaction, respectively. An ICRFB cell containing the Bi-C catalyst as the negative electrode exhibits a high energy efficiency of 86.54% with excellent capacity retention during charge–discharge cycling at room temperature. This study offers an intelligent hybrid material as a useful design principle for electrocatalysts capable of addressing the critical problems in ICRFBs.

Metallographic Documentation of the Degradation of Iron and Nickel Based Alloys in HCl and H<sub>2</sub>S Containing Environments, between 480 – 680 °C

Corrosion behavior of the alloys 1.7386 (P9), 1.4462, 1.4841, 1.4959 (Alloy 800HT) and 2.4816 (Alloy 600) was tested for 24, 72 and 240 h between 480 – 680 °C. The testing gas atmosphere contained 3.8 vol. % HCl, 200 ppm H2S and CO, CO2 and N2. It simulated conditions present in a thermal cracking process for post-consumer plastics. Samples were analyzed by metallography, SEM/EDX and XRD after corrosion experiments. Additionally, their mass loss during the test was evaluated. A multilayered structure of corrosion products grew on the samples during the corrosion experiments. The composition of the corrosion products depended not on the material, but on the testing temperature. At 680 °C chromium sulphide formed the outer layer, followed by a chromium oxide layer. Below these two layers a chlorine containing layer was observed. At 480 °C mainly nickel sulphide was detected, besides chromium oxide and iron- and chromium chloride. Especially at higher testing temperatures FeCl2 was not observed directly on the samples, but as colorless crystals at the colder parts of the testing equipment. At 680 °C the mass loss of the samples decreased with increasing nickel content. However, this effect changed entirely at lower testing temperatures. At 480 °C 1.7386 and 2.4816 showed nearly the same mass losses.

Dehydrogenation of Cumene to α-Methylstyrene on [Re,W]/γ-Al2O3(K,Ce)/α-Al2O3 and [Fe,Cr]/γ-Al2O3(K,Ce)/α-Al2O3 Porous Ceramic Catalytic Converters

The features of cumene dehydrogenation to α-methylstyrene on unique porous ceramic catalytic converters having the composition [Re,W]/γ-Al2O3(K,Ce)/α-Al2O3 and [Fe,Cr]/γ-Al2O3(K,Ce)/α-Al2O3, obtained using self-propagating high-temperature synthesis and the sol–gel method, have been studied. It has been established that at an optimum temperature of 625°C, the rhenium–tungsten-containing system has approximately 1.5 times higher catalytic activity than the iron–chromium system. On the Re–W-containing catalytic converter at the optimum temperature, the cumene conversion is ~71 mol %, the α-methylstyrene yield is ~77 mol % of theoretical, and the α-methylstyrene content in the products is ~35 mol %, with productivity for the desired product being ~7.4 g/(h gact.comp.). The degree of catalyst coking for 6 h of the experiment did not exceed 5 wt %.

Thermally Sensitized Membranes for Crude Oil-Water Remediation under Visible Light.

Effective remediation of produced water requires separating crude oil-water mixture and removing the dissolved organic pollutants. Membranes with selective wettability for water over oil enable the gravity-driven separation of an oil-water mixture by allowing water to permeate through while repelling oil. However, these membranes are often limited by their inability to remove the dissolved organic pollutants. In this work, a membrane with in-air superhydrophilic and underwater superoleophobic wettability is fabricated by thermal annealing of a stainless steel mesh. The resulting membrane possesses a hierarchical surface texture covered with a photocatalytic oxide layer composed of iron oxide and chromium oxide. The membrane exhibits chemical and mechanical robustness, which makes it suitable for remediation of crude oil and water mixture. Further, after being fouled by crude oil, the membrane can recover its inherent water-rich permeate flux upon visible light irradiation. Finally, the membrane demonstrates that it can separate surfactant-stabilized crude oil-in-water emulsion under gravity and decontaminate water-rich permeate by photocatalytic degradation of dissolved organic pollutants upon continuous irradiation of visible light.

The Interactive Effect of High Doses of Chromium(III) and Different Iron(III) Levels on the Carbohydrate Status, Lipid Profile, and Selected Biochemical Parameters in Female Wistar Rats.

The aim of the study was to evaluate the main and interactive effects of chromium(III) propionate complex (Cr3) supplementation and different iron supply on the carbohydrate metabolism, lipid profile and other selected biochemical parameters of rats. The experiment was carried out in a two-factor design, in which rats were fed a diet with different proportions of Fe(III) and Cr(III) for six weeks. Fifty-four healthy female Wistar rats were divided into nine experimental groups with different Fe(III) levels, i.e. adequate—control group (45 mg/kg)—100% recommended daily dietary dose of Fe for rodents, deficient (5 mg/kg) and oversupply (180 mg/kg—400%). At the same time they were supplemented with Cr(III) of doses 1 (adequate), 50 and 500 mg/kg of diet. The activity and concentrations of most biochemical parameters were measured with standard enzymatic, kinetic, and colorimetric methods. HOMA-IR and QUICKI indexes were calculated according to appropriate formulas. It was found that there was an interactive effect of high Cr(III) doses and different Fe(III) levels in the diet on the carbohydrate metabolism and insulin resistance indexes. The presented results suggested that iron deficient diet fed animals led to insulin resistance; however, an effect is attenuated by Cr(III) supplementation at high doses. There were no significant changes in the rats’ lipid profile (except for the high density lipoprotein cholesterol (HDL-C) level) and most of the other biochemical parameters, such as the leptin, aspartate aminotransferase (AST), alanine transaminase (ALT), total protein (TP), creatinine (Crea) and the urea (BUN) concentrations. The study proved that the Cr(III) supplementation, independently and in combination with diversified Fe(III) content in the diet, affected the carbohydrate metabolism and insulin resistance indexes but did not affect lipid profile and most of the other biochemical parameters in healthy rats. The findings proved the role of Fe and Cr(III) and their interactions on disturbances carbohydrates metabolism.

Ударостійкий чавун для молольних тіл

A study of the dynamic strength (impact resistance) of grinding bodies cast from low-chromium cast iron in a multi-seat chill mold depending on the chromium content in the alloy is carried out. As a starting point, cast iron of the following composition was used: carbon – 3,0%, silicon – 1,6%, manganese – 0,4%, sulfur – 0,05%, phosphorus – 0,06%. For the study, several batches of balls with a diameter of 60 mm were cast with different chromium content in cast iron, from 0 to 1%. Cast iron was smelted in a medium-frequency induction furnace, such as IChT, with the main lining on a charge of pure pig iron and steel low-carbon scrap. The temperature of cast iron production was 1500 °C. Liquid cast iron was subjected to alloying with medium carbon ferrochrome. Balls were cast in multi-seat chill molds. When tested for impact resistance, the grinding ball received a striking blow of mass 50 kg, falling from a height of 0,5 m. The frequency of application of dynamic loads was 10 beats per minute. Impact resistance was determined by the average number of impacts sustained by the grinding body prior to destruction. An increase in the impact resistance of ball castings has been established with an increase in the mass fraction of chromium in cast iron up to 1%. Moreover, the greatest increase in dynamic strength is observed with an increase in the mass fraction of chromium from 0,3% to 0,5%. With a further increase in the chromium content, the impact resistance of white low-alloy cast iron increases less noticeably, and in the presence of chromium 0,7-0,8% reaches a maximum. The difference in hardness from the surface (~ 52 HRC) to the center of the ball (~ 42 HRC) is a value of about 10 units. The established impact resistance of grinding bodies made it possible to conclude: when grinding solid rocks with high content of solid quartz, the use of low chromium cast iron as a material for grinding media is the most effective, as in terms of achieve high impact resistance, and to ensure cost-effective performance.

Innovative Method for Production of High Chrome Iron Castings using Ceramic Foam Filters

Innovative Method for Production of High Chrome Iron Castings using Ceramic Foam Filters

Effects of Iron Oxidation State and Chromium Distribution on the Corrosion Resistance of High Interstitial Stainless Steel for Down-Hole Application

The corrosion properties of Fe-Cr-Mn-C-N high interstitial austenitic stainless cast steels were investigated for down-hole application in sour environments. The two cast alloys contained 0.66% and 0.71% of total nitrogen and carbon. The corrosion properties of the alloys that were solution-treated and fast-cooled were directly responsible for high corrosion resistance in NaCl solution, including resistance to pitting corrosion resulting from a better distribution of chromium chemical compound in the high interstitial stainless cast steel. However, the sour corrosion resistance of the alloys decreased with the fast cooling rate, which can be attributed to the increased amount of ferrite containing Fe2+, which causes iron sulfide precipitate formation in H2S.

Mechanical failure of fresh nuclear grade iron–chromium–aluminum (FeCrAl) cladding under simulated hot zero power reactivity initiated accident conditions

The reactivity initiated accident (RIA) is a postulated accident in light water reactors initiated by a rapid increase in reactivity which causes an increase in fission rate and fuel temperature. One potential mode of fuel system failure during RIA is pellet cladding mechanical interaction (PCMI) due to the rapid thermal expansion of the fuel pellet. Simulated PCMI experiments were performed by rapidly pressurizing iron-chromium-aluminum (FeCrAl) cladding tube samples using a hydraulic modified burst test system, causing the specimens to burst under a biaxial loading path. Deformation and rupture of the specimens were tracked with a telecentric lens and high-speed camera system. Outer surface strains were calculated using digital image correlation (DIC) on speckle patterns painted on the specimens’ outer surfaces. Experiments were conducted at approximately 275 °C, representative of hot zero power RIA conditions. The failure hoop strain was DIC-calculated between approximately 1.8–3.4%, corresponding to quasi-static energy depositions of approximately 110–260 calories per gram UO2 assuming initial pellet-cladding contact. These conditions are very similar to the proposed energy deposition limit of 150 calories per gram UO2 for unirradiated zirconium-based cladding in US Nuclear Regulatory Commission (NRC) Draft Regulatory Guide 1327. A very small strain rate dependence was observed in the data, with the magnitude of the failure hoop strain decreasing slightly with increasing strain rate. This observed dependence may be relevant because the FeCrAl cladding strain rate will be approximately 20% higher than in zirconium-based cladding due to the harder neutron spectrum and resultant shorter neutron generation time.

SURFACE MODIFIED AND BISMUTH LOADED GRAPHITE FELTS FOR IMPROVEMENT OF ANODE ELECTRODE KINETICS IN IRON CHROMIUM REDOX FLOW BATTERY

In this study, anode electrodes were modified and bismuth loaded to enhance chromium redox reaction for iron chromium redox flow batteries. Graphite felt anode electrode surface was modified by two step chemical treatment. Corrosive HF was used as an etchant to increase porosity at the first step and oxidizing H2O2 was used to increase wettability of electrode at the second step. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses were used for the physical and chemical characterization of electrode materials. Cyclic voltammetry (CV) and linear sweeping voltammetry (LSV) techniques were conducted to investigate Cr2+/Cr3+ redox reaction kinetics for the modified electrodes with or without bismuth loading. Carbon nanoparticles formed on the surface and oxygen content increased. Contact angle for pristine graphite felt decreased from 132.6° to 128.5°, electrode wettability increased after treatment with HF and H2O2. Dispersion of bismuth particles became more uniform on modified electrode. Compared to untreated felt, the diffusion coefficient for Cr2+ has been almost doubled on modified graphite felt and Cr2+ concentration on the surface increased. When bismuth was in solution, reaction was controlled by charge transfer for modified electrode. In contrast, when bismuth was loaded onto the felt electrodes, reaction became diffusion controlled.

Recovery of Metals from Dry Shot Blast Waste Generated in the Stainless-Steel Production Process

Dry shot blast generated during stainless steel production contains high content of valued metals such as iron chromium and nickel. These metals are in the form of oxides and it can be used as a raw material in iron and steel. This work aims to study the feasibility of metals recovery from dry shot blast by smelting reduction process. Smelting reduction of dry shot blast by using coking coal as reductant was conducted in an induction furnace. The effect of metallurgical parameters e.g. stoichiometry ratio of reductant per oxygen containing in dry shot blast, CaO/SiO2 of slag forming and CaF2 in slag, on %recovery of metal product was investigated. The results based on this study showed that the weight of metal product increases with increased the amount of coke to about 1.5 of stoichiometric molar ratio. Increasing of coke above this amount leads to decrease %recovery of metal product. Moreover, the weight of metal product is increased when the ratio of CaO/SiO2 in slag decreased from 2 to 1. The chemical composition of the metal product is in the range of commercial grade and it can be used as raw materials to produce steel and cast iron alloy.Dry shot blast generated during stainless steel production contains high content of valued metals such as iron chromium and nickel. These metals are in the form of oxides and it can be used as a raw material in iron and steel. This work aims to study the feasibility of metals recovery from dry shot blast by smelting reduction process. Smelting reduction of dry shot blast by using coking coal as reductant was conducted in an induction furnace. The effect of metallurgical parameters e.g. stoichiometry ratio of reductant per oxygen containing in dry shot blast, CaO/SiO2 of slag forming and CaF2 in slag, on %recovery of metal product was investigated. The results based on this study showed that the weight of metal product increases with increased the amount of coke to about 1.5 of stoichiometric molar ratio. Increasing of coke above this amount leads to decrease %recovery of metal product. Moreover, the weight of metal product is increased when the ratio of CaO/SiO2 in slag decreased from 2 to 1. The chemical composition of the metal product is in the range of commercial grade and it can be used as raw materials to produce steel and cast iron alloy.

Nature of Reactive Oxygen Intermediates on Copper-Promoted Iron–Chromium Oxide Catalysts during CO2 Activation

A series of copper-promoted iron–chromium oxide catalysts with various copper loadings are investigated for CO2 activation (reverse water–gas shift reaction) to determine the nature of surface oxyg...

Comparative Study on the Corrosion Behaviours of High-Silicon Chromium Iron and Q235 Steel in a Soil Solution

Comparative Study on the Corrosion Behaviours of High-Silicon Chromium Iron and Q235 Steel in a Soil Solution

Short-Range Order in Fe-Cr Alloys: Lattice Monte Carlo Modelling

Short-range order in Fe–Cr alloys is investigated by Monte Carlo method. The modelling was performed by Metropolis algorithm using the LAMMPS software package. Modelling results were analyzed by the visualization and data analysis package Ovito. The model of the alloys supposed that the lattice structure was fixed and interaction exists between the first and the second neighbours. The Fe–Cr interaction was established with the use of interatomic interaction potential Abell–Brenner–Tersoff (ABOP). Different concentrations of substitutional impurity of chromium in iron were investigated, viz. 5–50 at. %. The energy of mixing in the Fe–Cr system was calculated for various concentrations of substitutional impurity. Calculation showed that the chosen interaction potential reproduces correctly the changes of the sign of the energy of mixing as a function of Cr concentration. When applied in Monte Carlo kinetic modelling the potential predicts correctly the immiscibility of initially chaotic Fe–Cr alloys as a function of Cr content. The Cowley short-range order parameter is determined that is used for quantitative estimation of the degree of ordering. A strong tendency towards ordering in Cr distribution is observed at low concentrations which is exhibited by negative values of short-range order parameters, in accordance with the experiment.

ELECTROCHEMISTRY STUDY ON THE RELATIONSHIP BETWEEN GRAIN BOUNDARY STATE AND CORROSION BEHAVIOR OF ULTRAFINE GRAINED IRON CHROMIUM ALLOY

ELECTROCHEMISTRY STUDY ON THE RELATIONSHIP BETWEEN GRAIN BOUNDARY STATE AND CORROSION BEHAVIOR OF ULTRAFINE GRAINED IRON CHROMIUM ALLOY. Research on stainless steel corrosion resistance continues to grow today. This reality cannot be separated from the needs of stainless steels in various fields, one of which is bio-implant. In this research, the effect of grain size on the corrosion behavior of iron-chromium (Fe-Cr) alloy was investigated. Coarse grain Fe-Cr alloy was first processed with equal channel angular pressing (ECAP) for eight cycles to obtain ultrafine grain structure. The coarse and ultrafine grain samples then were then tested using XRD, SEM-EBSD, and the pitting corrosion properties tested using potentiodynamic polarization method in NaCl 1 M solution. The result of XRD dan SEM-EBSD shows that the initial sample is truly has a coarse grain structure, while ECAP produces an ultrafine grain structure. Corrosion test results showed that the ultrafine grain sample had better pitting corrosion resistance compared to the coarse grain sample. This behavior is related to the rate of passivation that depends on non-equilibrium grain boundaries, which can be easily observed in the ultrafine grain structure. Based on these results, it can be concluded that the ultrafine grain Fe-Cr alloy has a better corrosion resistance compared to the coarse grain.

Effect of Chelation on Iron–Chromium Redox Flow Batteries

The iron–chromium (FeCr) redox flow battery (RFB) was among the first flow batteries to be investigated because of the low cost of the electrolyte and the 1.2 V cell potential. We report the effect...