Addition Of Chromium Research Articles

Chromium Addition Effect on Wear Properties of Cast-Iron Material

A new cast iron material with a higher Cr content than usual is analyzed by chemical, micro-structural and friction coefficient point of view. The material was obtained by classical melting and the results compared with the experimental results obtained from a standard cast-iron used for applicative disk brake. Four different mechanical solicitation rates were used on the same material surface and the same load. The solicitation regime can be considered as semi-liquid and similar to a raining day experimental conditions. In this paper no thermal considerations were present or discussed. The results present a bigger friction coefficient of the new material and further considerations are necessary for example in a different friction regime.

Effects of chromium addition on fracture toughness and hardness of oriented bulk Fe2B crystals

Effects of different chromium addition on the microstructure, fracture toughness and hardness of oriented Fe2B bulk were investigated. The results indicate that, with increasing Cr addition, the interplanar spacings of the two perpendicular crystal planes ((002) and (200)) of oriented bulk Fe2B crystals have different variation trends, and the transversal fracture toughness of oriented Fe2B bulk increases first and then decreases, while the longitudinal fracture toughness decreases gradually. The results also indicate that, with increasing Cr addition, the hardness of longitudinal section increases first and then decreases; however, the hardness of transversal section decreases gradually. Furthermore, by analyzing the variation trends of surface energies and interplanar spacings of two perpendicular crystal planes, it can be concluded that, the variation of interplanar spacing due to Cr solution should be the essential reason for different fracture toughness and hardness of oriented Fe2B crystals.

Development and property evaluation of nuclear grade wrought FeCrAl fuel cladding for light water reactors

Development of nuclear grade, iron-based wrought FeCrAl alloys has been initiated for light water reactor (LWR) fuel cladding to serve as a substitute for zirconium-based alloys with enhanced accident tolerance. Ferritic alloys with sufficient chromium and aluminum additions can exhibit significantly improved oxidation kinetics in high-temperature steam environments when compared to zirconium-based alloys. In the first phase, a set of model FeCrAl alloys containing 10–20Cr, 3–5Al, and 0–0.12Y in weight percent, were prepared by conventional arc-melting and hot-working processes to explore the effect of composition on the properties of FeCrAlY alloys. It was found that the tensile properties were insensitive to the alloy compositions studied; however, the steam oxidation resistance strongly depended on both the chromium and the aluminum contents. The second phase development focused on strengthening Fe–13Cr–5Al with minor alloying additions of molybdenum, niobium, and silicon. Combined with an optimized thermo-mechanical treatment, a thermally stable microstructure was produced with improved tensile properties at temperatures up to 741 °C.

Computational design and development of novel Al-Mg-Sc-Cr alloy

Purpose – The purpose of this paper is to design and develop precipitation hardened Al-Mg alloy imparting enhanced strength with acceptable ductility through minor addition of Sc and Cr by using multi-objective genetic algorithm-based searching. In earlier attempts of strengthening aluminum alloys, owing to the formation of Al3Sc and Al7Cr phase, addition of Sc and Cr have yielded attractive precipitation hardening, respectively. Both the Al-Sc and Al-Cr system are quench sensitive due to presence of a sloping solvus in their phase diagrams. It is also known that both the Al3Sc and Al7Cr phases nucleate directly from the supersaturated solid solution without formation of GP-zones or transient phases prior to the formation of the Al3Sc and Al7Cr. Sc also found to have beneficial effect on the corrosion property of such alloys. In view of the above, it is of interest to explore the possibility of enhancing the age hardening effect in Al-Mg alloy by addition of Sc and Cr. Design/methodology/approach – The paper uses an approach where experimental information of two different alloy systems (namely, Al-Mg-Sc and Al-Cr) has been combined to generate a single database involving the potential features of both the systems with the aim to formulate the suitable artificial neural network (ANN) models for strength and ductility. The models are used as the objective functions for the optimization process. The patterns of the optimized Pareto front are analyzed to recognize the optimal property of the alloy system. The hitherto unexplored Al-Mg-Sc-Cr alloy, designed from the Pareto solutions and suitably modified on the basis of prior knowledge of the system, is then synthesized and characterized. Findings – The paper has demonstrated the ANN- and genetic algorithm (GA)-based design of a hitherto unexplored alloy by utilizing the existing information concerning the component alloy systems. The paper also established that analyses of the Pareto solutions generated through multi-objective optimization using GA provide an insight of the variation of the parameters at different combination of strength and ductility. It also revealed that the Al-Mg-Sc-Cr alloy has exhibited a two-stage age hardening effect. The first and second stages are due to the precipitation of Al3Sc and Al7Cr phases, respectively. Research limitations/implications – In the present study the two alloy systems are used in tandem to develop models to describe the properties involving the distinct mechanistic features of phase evolution inherent in both the systems. Though the ANN models having the capability to capture huge non-linearity of a system have been employed to predict the convoluted effects of those characteristics when an alloy containing Mg, Sc and Cr are added simultaneously, but the ANN models predictions can be checked experimentally by the future researchers. Practical implications – The paper demonstrates the role of scandium and chromium addition on the ageing characteristics of the alloy by analyzing the age hardening behavior of the designed alloy in cast and cold rolled condition clearly. Originality/value – The approach stated in this paper is a novel one, in the sense that experimental data of two different alloy systems have been clubbed to generate a single database with the aim to formulate the suitable ANN models for strength and ductility.

Mechanical Properties of Molybdenum Disulfide and the Effect of Doping: An in Situ TEM Study.

Direct observations on nanopillars composed of molybdenum disulfide (MoS2) and chromium-doped MoS2 and their response to compressive stress have been made. Time-resolved transmission electron microscopy (TEM) during compression of the submicrometer diameter pillars of MoS2- and Cr-doped MoS2 (Cr: 0, 10, and 50 at %) allow the deformation process of the material to be observed and can be directly correlated with mechanical response to applied load. The addition of chromium to the MoS2 changed the failure mode from plastic deformation to catastrophic brittle fracture, an effect that was more pronounced as chromium content increased.

Optimisation of copper catalyst by the addition of chromium for the chemical vapour deposition growth of monolayer graphene

The effect of adding chromium (Cr) to the copper catalyst for chemical vapour deposition growth of graphene is investigated. We observe a suppression of the formation of multilayer islands of graphene in the Cr-rich regions. This is shown with optical microscopy, scanning electron microscopy and scanning Raman spectroscopy. In addition, carbon isotope labelling is employed to elucidate the mechanism by which the formation of multilayer islands is minimised. The use of mixed catalysts is an important step in the optimisation of catalytic growth of graphene.

Effect of Inhibitor Coating of a Ceramic Mould on the Surface Quality of an AM60 Alloy Cast with Cr and V

Abstract The work presents the results of the investigations of the effect of inhibitors coated on the internal walls of a ceramic mould on the quality of the obtained casts made of the AM60 alloy containing additions of chromium and vanadium. In order to reduce the reactivity of magnesium alloy cast by the technology of investment casting with the material of the mould and the ambient atmosphere, solid inhibitors were applied in the form of a mixture of KBF4 and H3BO3 after the stage of mould baking and before the mould’s being filled with the liquid alloy. For the purpose of examining the effect of the inhibitors on the surface quality of the obtained casts, profilometric tests were performed and the basic parameters describing the surface roughness, Ra, Rz and Rm, were determined.

DSC Analysis Of Order–Disorder Transition In Ni3Al Based Alloys From Ni-Al-Cr System

AbstractNi-Al-Cr system is significant for industrial alloys based on intermetallic phase Ni3Al, that crystallizes in crystal lattice L12. It is indicated as γ′, contrary to disordered phase γ which occurs with addition of chromium. DSC analysis was performed on alloys of chemical composition from Ni75Al25÷Ni75Cr25 range of Ni-rich part of Ni-Al-Cr system. In addition, few measurements were conducted using DTA method. Based on curves registered, it was possible to identify characteristic temperature during heating and cooling of the sample. It corresponds to existence of phase boundary γ′+γ / γ in examined alloys. Results of thermal analysis were compared with results obtained with other method performed by authors which is solution calorimetric method.

Influence of Vanadium and Chromium Addition on Morphology and Composition of Iron Based Phases in AlSi10MgMn Alloy

Application of secondary Al-Si alloys is mostly influenced by amount of impurities. Detrimental effect of iron, as the most harmful impurity, refers mainly to morphology of iron intermetallic phases. Morphology of iron phases can be influenced by several methods from which the most common is addition of some elements. In primary alloys manganese is commonly used, but its influence is not such favourable in high iron levels because of so-called sludge phase formation. Higher iron content thus requires other alloying elements which can be vanadium, chromium or others. In this article, vanadium and mutual vanadium and chromium influence on iron phase morphology and chemical composition is analysed by optical microscopy, SEM observations and EDX analysis.

Preliminary Results on Microstructural, Chemical and Wear Analyze of New Cast Iron with Chromium Addition

A new cast-iron material was obtained by melting in an induction furnace. The material was microstructural and chemical characterized before and after a wear test. We analyze the chemical composition of the material at macro-scale using a Spark Spectrometer and at micro-scale using Dispersive Energy Spectrometer. Microstructure before and after the external solicitations was observed using a Scanning Electron Microscope. We also evaluate the influence of external force on the dendrites microstructural and chemical modification.

The deformation texture of rolled ribbons of copper-based alloys as a condition of producing a sharp cubic texture upon recrystallization

It has been shown that a specific quantitative relationship of main textural components after cold deformation (by rolling to 98.6–99%) of copper alloys determines the possibility of producing a sharp cubic texture in the ribbons after subsequent recrystallization annealing. The binary alloys of copper with nickel (up to 40 at %) and of copper with additions of iron and chromium correspond to this criterion. It has been found that the optimum deformation texture can be created in some ternary copper-nickel alloys with addition of Cr, Fe or Mn. It has been shown that the analysis of the component composition of deformation textures using the orientation distribution function can yield more precise predictions than the stacking fault energy values, as well as make it possible to obtain a cubic texture upon subsequent recrystallization.

Effect of tannery wastes and biochar on soil chemical and physicochemical properties and growth traits of radish

Abstract Tannery wastes can be used in soil as organic manure. The aim of this research was to study the effects of tannery wastes (before a chromium addition step) and biochar on soil chemical and physicochemical properties and radish yield. Treatments included three levels of tannery waste (0, 2.5, and 5%) and two levels of biochar (0 and 2.5 t ha−1) in a completely randomized design (factorial) with three replications. The treated pots were kept under field capacity condition for three months; thereafter, five radish seeds were sown at 1 cm depth in soil of each pot. The results showed that tannery wastes and biochar treatments resulted in an increase in soil nitrogen and phosphorus contents and their concentrations in radish root and above ground biomass, but electrical conductivity of soil was decreased and had no effect on soil potassium content. The tannery waste treatment increased soil pH after plant harvest. It also significantly increased radish fresh and dry matter weight, but the biochar treatment yielded a slight increase. It is concluded that application of tannery wastes and biochar may be useful due to their high nutrient contents in soils lacking organic carbon under arid and semi-arid regions, thereby improving growth and increasing plant yield.

Corrosion Behavior of High Performance Offshore Platform Steel with Chromium and Nickel Addition in the Environment Containing Chloride Ions

The characterization of corrosion products formed on a high performance offshore platform steel in the environment containing chloride ions has been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), electron probe microanalysis (EPMA) and electrochemical impedance spectroscopy (EIS). The results reveal that the corrosion process can be divided into the initial stage and the later stage. The main constituents of rust layers are α-FeOOH, β-FeOOH, γ-FeOOH, Fe3O4 and large amounts of amorphous compounds. With increasing corrosion time, the mass fraction of α-FeOOH and Fe3O4 increased, while that of γ-FeOOH and β-FeOOH changed slightly. The enrichment of Cr and Ni at the inner/outer interface, especially the side of inner rust, can be observed in the later corrosion stage of Cr-Ni steel, which can promote the formation of compact inner rust layer, impeding the transmission of corrosion mediums and slowing down the electrochemical reaction process.

The Prospects In Designing New Generation Of High Temperature Coatings In Automobile Engines

AbstractThe influence of the chromium layer with the thickness of 1 micrometer sputter-deposited on the X33CrNiMn23-8 and X50CrMnNiNbN21-9 steel surfaces on the oxidation behavior of these steels has been studied at 1173 K in air, using the microthermogravimetric technique. It has been found that coated materials show very good oxidation resistance under isothermal conditions, comparable with that of chromia formers, due to the formation of Cr2O3scales on their surfaces. It has been also demonstrated that the positive effect of chromium addition on the oxidation resistance of investigated steels is observed during a much longer period of time than the life-time of the chromium coating.

The effect of a cinnamon-, chromium- and magnesium-formulated honey on glycaemic control, weight loss and lipid parameters in type 2 diabetes: an open-label cross-over randomised controlled trial.

This randomised controlled trial assessed the acute and long-term effects of daily supplementation of kanuka honey, formulated with cinnamon, chromium and magnesium on glucose metabolism, weight and lipid parameters in individuals with type 2 diabetes. Twelve individuals with type 2 diabetes received 53.5 g of a formulated honey and a control (non-formulated) kanuka honey in a random order for 40 days, using cross-over design. Fasting glucose, insulin, HbA1c, lipids and anthropometric measures were measured at baseline and end of treatment. A meal tolerance test was performed at baseline to assess acute metabolic response. There was no statistically significant difference in acute glucose metabolism between treatment groups, as measured by the Matsuda index and AUC for glucose and insulin. After the 40-day intervention with honey, fasting glucose did not differ significantly between the two treatments (95 % CI -2.6 to 0.07). There was no statistically significant change in HbA1c or fasting insulin. There was a statistically significant reduction in total cholesterol by -0.29 mmol/L (95 % CI -0.57 to -0.23), LDL cholesterol by -0.29 mmol/L (95 % CI -0.57 to -0.23) and weight by -2.2 kg (95 % CI -4.2 to -0.1). There was a trend towards increased HDL and reduced systolic blood pressure in the intervention treatment. The addition of cinnamon, chromium and magnesium supplementation to kanuka honey was not associated with a significant improvement in glucose metabolism or glycaemic control in individuals with type 2 diabetes. Use of the formulated honey was associated with a reduction in weight and improvements in lipid parameters, and should be investigated further.

Cover Picture: Materials and Corrosion. 4/2015

Cover:The composition of the high strength austenitic steel Sanicro 25 is characterized by a high chromium content and additions of tungsten, niobium, copper as well as significant levels of nitrogen. The steel microstructures in the bulk of the sample and the sub surface zones after exposure times of 1000, 3000 and 10000 hours in steam at temperatures in the range 600–750 °C were analysed by scanning and transmission electron microscopy as well as X‐ray diffraction. Additionally, the surface oxide scale formation as well as the oxidation induced sub surface microstructural changes were studied using depth profiling by secondary neutrals mass spectrometry. In the as‐received condition the only detectable precipitate was (Nb,Cr)N‐base Z‐phase. The oxidation rates were found to be only slightly higher than those of a typical nickel base wrought material such as alloy 617. In the subsurface zones depletion of scale forming elements was accompanied by enrichment of tungsten and copper rich phases. In spite of the fact that precipitate sizes were, especially after exposure at lower temperatures, quite small unequivocal identification of the phases present in the alloy microstructure was possible by combining EDX and WDX data with results from EBSD analyses. The cover picture illustrates how information about elements present in the various precipitates as analysed by EDX and WDX can be compared with compounds prevailing in the structure database ICSD. Subsequently, an EBSD mapping of the respective best fitting compounds was made. The EBSD mapping reveals precipitates of (Cr,Nb)N‐base Z‐phase, Cr2N, tungsten rich µ‐phase and M23C6 carbides of various composition.More information can be found in: J. Zurek, S.‐M. Yang, D.‐Y. Lin, T. Hüttel, L. Singheiser, W. J. Quadakkers, Microstructural stability and oxidation behaviour of Sanicro 25 during long term steam exposure in the temperature range 600–750 °C, Materials and Corrosion, 2015, 66, 315.

Effect of drying conditions on the textural, structural and catalytic properties of Cr/ZrO2–SO4: n-hexane conversion

Aerogel and xerogel catalysts based on sulfated zirconia doped with chromium are prepared by sol–gel method. The effects of drying mode and calcination temperature are reflected in the characteristics of the final solids. The addition of chromium to aerogel sulfated zirconia not only provides an important development of the specific surface area from 100 to 213 m2 g−1; but also stabilizes a pure metastable ZrO2 tetragonal phase in a large calcination temperature domain. In addition, the aerogels develop active sulfate groups and preserve them on the surface even at high heating. Those characteristics contribute to the improvement of catalytic performances of sulfated zirconia in n-hexane conversion. However, in the case of xerogels, the increase of temperature treatment leads to the loss of sulfate active groups and porosity destruction which make them completely inactive in spite of the development of ZrO2 tetragonal phase.

탄소강의 유동가속부식에 미치는 크롬의 영향

The alloy content of structural materials of nuclear power plants has been recognized an important factor in predicting flow accelerated corrosion (FAC). In particular, many literature data reported that chromium content is one of the most important alloying element and even a small amount of chromium is effective to suppress FAC. This report reviewed and compared chromium models of Ducreux, Bouchacourt, and Kastner which were used in predicting FAC rates. The plant data indicate that Ducreux model may be conservative for the specimen containing 0.15 wt% chromium. The related articles were reviewed as follows. Combined effects of chromium content, pH, temperature, dissolved oxygen (DO), flow velocity, test time, and kinds of amine on the FAC rate were described. 0.1 wt% chromium in steel did not affect the FAC rate with changes in pH. The FAC rates pronounced with higher flow rate and increased with increasing test duration(600 d) for 0.013 wt% chromium. The FAC rates in mixed amine chemistry were higher than in ammonia chemistry, which may be lessened by the addition of chromium to the steel.

Studies of the effects of addition of P and Cr on microstructure and electrical resistivity of nanocrystalline CoFe thin films

In this study, CoFe, CoFeP and CoFeCr thin films were electrodeposited at different current densities and the relation between their microstructure and electrical resistivity were studied. In order to characterize deposited films, field emission scanning electron microscope (FE-SEM) equipped with energy dispersive X-ray spectrometer, X-ray diffraction system and four probe-point methods were utilized. The results showed that an increase in the applied current density results in increasing iron, phosphorus and chromium contents in the coatings. FE-SEM and SEM micrographs illustrated that addition of phosphorous and chromium to CoFe changes the surface morphologies. Increasing current density caused formation of BCC (Fe) phase structure along with FCC (Co) phase in CoFe coatings. However, all CoFeP and CoFeCr thin films were consisted of only BCC (Fe). Estimation of crystallite size of the deposited films by Scherrer formula showed that all coatings had nanocrystalline structures and decreasing of crystallite size led to significant increase in electrical resistivity of the films, which was according to “scattering hypothesis”. CoFeP thin films showed higher electrical resistivity than those of CoFe and CoFeCr films.

The Deformation, Strain Hardening, and Wear Behavior of Chromium-Alloyed Hadfield Steel in Abrasive and Impact Conditions

The alloying of Hadfield steels aims at enhanced mechanical properties and improvements in the wear resistance. In this work, the impact and abrasive properties of a chromium-alloyed high-manganese Hadfield steel were experimentally studied using a wide variety of testing techniques and characterization methods. In addition, an in-service sample was characterized to identify the wear and hardening mechanisms in a real application (jaw crusher). The dynamic mechanical behavior of the steel was determined using the Hopkinson split bar technique. The abrasion properties were studied with three-body abrasion tests using several different natural abrasives. The effects of existing plastic strain and normal loading on the surface hardening and wear rate were further investigated with scratch testing. High-velocity impact testing was performed to evaluate the effect of pre-strain on the impact wear behavior of the material. It was shown that the dynamic loading affects both the yield behavior and the strain hardening rate of the studied steel. The connection between pre-strain, hardness, and wear rate in abrasion was established. In impact conditions, plastic straining of the surface layer first has a positive effect on the wear resistance, but when strain hardening reached the observed ductility limit, it showed an adverse effect on the material’s performance. The addition of chromium and an increase in the manganese content from the nominal ASTM Hadfield composition provided some improvements in the strength, ductility, and surface hardening of the studied steel.