Addition Of Chromium Research Articles

Anti-oxidation effect of chromium addition for TiFe hydrogen storage alloys

Anti-oxidation properties of Cr substitution were investigated by comparing TiFe and TiFe0.9Cr0.1. Kinetic measurements reveal that the degradation rate of TiFe0.9Cr0.1 is slower than that of TiFe, indicating that Cr substitution drastically enhances the anti-oxidation properties of the mother alloy TiFe. In order to understand the mechanism of this effect, X-ray photoelectron spectroscopy (XPS) was used to identify the surface chemical state of these alloys, which indicates that Cr plays quite an important role in the suppression of surface oxidation. It is clarified that the deactivation of TiFe is caused by the oxidation of Ti on the surface and, as a result, the obstruction of hydrogen penetration. On the contrary, with the substitution of Cr for Fe in TiFe0.9Cr0.1, the Ti oxidation becomes more difficult even though the Cr was totally oxidized, which makes it easier to keep the initial activated state of hydrogenation (Ti with a low oxidation state). It also further demonstrated that Cr acts as a sacrificial element, undergoing complete oxidation to protect Ti from oxidation, and assists in keeping metallic Ti0, which is crucial for maintaining the hydrogen absorption kinetics. Therefore, the Cr substitution for Fe significantly improves the anti-oxidation properties of TiFe-based alloys.

Investigation of Optical Properties of Polymeric Composite (PVA/PVP) Doped by Potassium Chromate

The practical out comes of the present study involves preparation of [Poly(vinyl) alcohol (PVA)]/[ pyrrolidone (PVP)] (50:25 wt%) composites doped by Potassium Chromate (K2CrO4) purity of 99% with different volume concentration (1.6% up to 7.7%) by simple solution casting method. The optical properties of the films were verified using UV-Vis-NIR spectroscopic analysis. The optical constants such as absorption coefficient, refractive index,Extinction coefficient real and imaginary parts of dielectric constant have been investigated, results show that the optical constants are affected by concentration of Potassium Chromate addition in the (PVA:PVP) blend . The optical gap decreased from 3.5 eV for pure (PVA:PVP) polymer blend to 2.5 eV for [(PVA:PVP)/ Potassium Chromate 7.7 wt%] while the refractive index increased from 2.43 to 2.74 depended on Potassium Chromate additive.Hybrid polymeric composites of Potassium Chromate additive in (PVA:PVP) can be considered as a promising material for different electronic application.

AUBERT & DUVAL PER72

Abstract Aubert and Duval PER72 (NiCr18Co15TiMoAI alloy) is a precipitation hardening, nickel-base superalloy. The alloy is solid solution strengthened by additions of chromium, cobalt, molybdenum, and tungsten, while additions of titanium and aluminum provide precipitation strengthening. Aubert & Duval PER72 combines high strength with metallurgical stability as demonstrated by excellent impact strength retention after long exposures at elevated temperatures. It also exhibits good oxidation resistance, as well as excellent resistance to sulfide corrosion. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on low temperature performance, high temperature performance, and corrosion resistance as well as forming and heat treating. Filing Code: Ni-787. Producer or source: Aubert & Duval S.A. (a member of the Eramet Group).

The application of NiCrPt alloy targets for magnetron sputter deposition: Characterization of targets and deposited thin films

NiSi thin films are extensively used in advanced semiconductor devices due to their desirable electrical properties. Recently, the incorporation of platinum (Pt) into NiSi thin films, resulting in NiPtSi, has been pursued to mitigate the agglomeration of NiSi and delay its transformation into NiSi2. Typically, in semiconductor manufacturing, NiPt films are deposited onto silicon wafers through magnetron sputtering using NiPt sputtering targets. To further enhance the properties of these thin films, chromium (Cr) was introduced into the NiPt target. Initially, NiCrPt targets were fabricated through thermal mechanical treatment. Subsequently, NiCrPt thin films were deposited via magnetron sputtering using these NiCrPt targets. The study results indicate that, in comparison to NiPt targets, the addition of chromium offers several advantages: (1) it refines the grain size of NiPt in both bulk and thin film states; (2) it effectively reduces microcracks in the thin films; and (3) it increases the sputtering rate of NiCrPt targets, owing to an increased pass-through flux of 100 % and the refined grain size of the NiCrPt target. These findings provide valuable insights into the design and development of NiPt alloy sputtering targets and the production of crack-free thin films via magnetron sputtering, marking a significant advancement in the field of semiconductor manufacturing.

Mechanical properties of spinel (MgCr2O4) phase containing alumino-silicate glass-ceramic

This research study explores the addition of chromium (Cr6+) ions as a nucleating agent in the alumino-silicate-glass (ASG) system (i.e., Al2O3-SiO2-MgO-B2O3-K2O-F). The important feature of this study is the induction of nucleation/crystallization in the base glass matrix on addition of Cr6+ content under annealing heat treatment (600 ± 10 °C) only. The melt-quenched glass is found to be amorphous, which in the presence of Cr6+ ions became crystalline with a predominant crystalline phase, Spinel (MgCr2O4). Microstructural experiment revealed the development of 200–500 nm crystallite particles in Cr6+-doped glass-ceramic matrix, and such type microstructure governed the mechanical properties. The machinability of the Cr-doped glass-ceramic was thereby higher compared to base alumino-silicate glass (ASG). From the nano-indentation experiment, the Young’s modulus was estimated 25(±10) GPa for base glass and increased to 894(±21) GPa for Cr-doped glass ceramics. Similarly, the microhardness for the base glass was 0.6(±0.5) GPa (nano-indentation measurements) and 3.63(±0.18) GPa (micro-indentation measurements). And that found increased to 8.4(±2.3) (nano-indentation measurements) and 3.94(±0.20) GPa (micro-indentation measurements) for Cr-containing glass ceramic.

Cr-substituted Mn–Zn ferrite nanoparticles: A study of optical, photocatalytic degradation, and radiation shielding evolution

In this work, we investigate the impact of chromium (Cr) additives on the optical, photocatalytic degradation and the radiation attenuation features of chromium-manganese (Mn)-zinc (Zn)-based spinel nanoferrite (named MZCF-nanoferrites. The Kubelka-Munk approach of reflectance results and Tauc's plots were exploited to verify the energy gap (Eg) of the MZCFx ferrite nanoparticles. The nanoferrites MZCF0, MZCF1, MZCF2, MZCF3, MZCF4, and MZCF5 have Eg values 1.826, 1.811, 1.797, 1.784, 1.772, and 1.769 eV, respectively. The comparative study of the photocatalytic degradation for the optimal (Mn0.8Zn0.2Cr0.1Fe1.9O4) nanoferrite sample and many reported photocatalytic materials evidenced that the MZCF5 nanoferrite has methylene blue dye removal ability higher than those materials (96.38 %, in 60 min). Moreover, this comparative study showed the improved photocatalytic degradation stability performance of the present nanoferrites (just 1.65 % efficiency was decreased after five cycles). The present study proposes a novel approach toward spinel nanoferrites, focusing on the optical and photocatalytic characteristics of the MZCFx-nanoferrites that can be applicable in water treatment fields. Examining linear attenuation coefficient (LAC) of MZCFx-nanoferrite at 0.662 MeV, we observe increased LAC values 0.286 cm−1 to 0.344 cm−1 with increasing Cr additions. Conversely, the half value layer (HVL) values at 0.662 MeV decreased 2.421 cm–2.017 cm with increasing Cr additions. By comparing the HVL values of the MZCFx-nanoferrites at 0.662 MeV to some selected radiation shielding materials, the HVL of the MZCFx-nanoferrites showed smaller values. These findings offer promising perspectives for optimization of spinel nano materials for use in radiation shielding applications.

Evidence of turmeric adulteration with lead chromate across South Asia

Food adulteration with toxic chemicals is a global public health threat. Lead chromate adulterated spices have been linked with lead poisoning in many countries, from Bangladesh to the United States. This study systematically assessed lead chromate adulteration in turmeric, a spice that is consumed daily across South Asia. Our study focused on four understudied countries that produce >80 % of the world's turmeric and collectively include 1.7 billion people, 22 % of the world's population. Turmeric samples were collected from wholesale and retail bazaars from 23 major cities across India, Pakistan, Sri Lanka, and Nepal between December 2020 and March 2021. Turmeric samples were analyzed for lead and chromium concentrations and maximum child blood lead levels were modeled in regions where samples had detectable lead. A total of 356 turmeric samples were collected, including 180 samples of dried turmeric roots and 176 samples of turmeric powder. In total, 14 % of the samples (n = 51) had detectable lead above 2 μg/g. Turmeric samples with lead levels greater than or equal to 18 μg/g had molar ratios of lead to chromium near 1:1, suggestive of lead chromate adulteration. Turmeric lead levels exceeded 1000 μg/g in Patna (Bihar, India) as well as Karachi and Peshawar (Pakistan), resulting in projected child blood lead levels up to 10 times higher than the CDC's threshold of concern. Given the overwhelmingly elevated lead levels in turmeric from these locations, urgent action is needed to halt the practice of lead chromate addition in the turmeric supply chain.

Effects of Cr Addition on the Microstructure and Mechanical Properties of an Al-Si-Cu-Mg Alloy.

The effects of chromium (Cr) addition ranging 0.1-0.3 wt.% on the microstructure and mechanical properties of Al-7Si-4Cu-0.25Mg (wt.%) alloy have been investigated. The cast Cr-free alloy consisted of α-Al, eutectic Si, Q-Al5Mg8Cu2Si6 and θ-Al2Cu phases. Doping of Cr resulted in the appearance of a polyhedron-shaped α-Al13Cr4Si4 phase with a cubic structure. The Al13Cr4Si4 particles were found to embed with Al2Cu blocks and bring about size reduction for the Al2Cu blocks. The area fraction of Al13Cr4Si4 monotonously increased with Cr content. After T6 treatment, the Al2Cu blocks almost fully dissolved and transformed to θ'-Al2Cu precipitates in the Cr-containing alloys. TEM observation revealed relatively large-sized θ' precipitates attached to Al13Cr4Si4 dispersoids. The Cr-containing alloys showed impressive mechanical properties, with the peak strength up to 452 MPa at room temperature. The ductility exhibited an increasing trend with Cr content, but the strength dropped dramatically when the Cr content reached 0.3 wt.%. It is suggested that the strength contribution from the Al13Cr4Si4 phase is limited, especially at an elevated temperature.

Analysis of Tribological Properties of Hardfaced High-Chromium Layers Subjected to Wear in Abrasive Soil Mass.

This article presents the results of abrasion wear resistance tests of wear-resistant steel and surfacing under laboratory conditions and natural operation. Abrasion wear resistance determined on the basis of the study by determining geometrical characteristics of the alloying additives using computer image analysis methods, as well as examining the changes occurring on the surface of the workpieces and their wear intensity. Based on the results obtained from laboratory tests, it was noted that AR steel exhibited 14 times greater wear than the padding weld. This wear is affected by alloy additives, which, for the padding weld, are chromium additives. The microstructure image shows that soil mass had a destructive effect mainly on the matrix of the material, whereas in the areas with high concentrations of chromium precipitates, this effect was significantly weaker. The operational test results showed that within the area of the tine subjected to hardfacing, the material loss was lower than that for the same area of the tine in the as-delivered state. For the hardfaced tine, a 7% loss of volume was noted in relation to the operating part before testing and following the friction process. However, for the operating part in the as-delivered state, this difference amounted to 12%.

Effect of chromium and molybdenum addition on the matching mechanism of strength−ductility−toughness of low carbonmedium manganese steel

Low carbon medium manganese steel with chromium and molybdenum addition (4MnCM), alongside a control group without these additions (4Mn), was developed. The quenching (860 °C) and tempering (620 °C) heat treatment process was applied to both steel groups. The influence of Cr and Mo on the microstructure evolution and mechanical properties was examined. The findings revealed that, the low−temperature impact energy values (KV2) of 4MnCM at −60 and −84 °C were enhanced by 104 and 107 J, in comparison to 4Mn. The yield and tensile strength saw an increase of 100 MPa. The higher low-temperature toughness of 4MnCM is attributed, on one hand, to the addition of Cr and Mo, which inhibiting deformation twinning through enhances the stacking fault energy (SFE) of reversed austenite. On the other hand, it is due to the absence of coarse ε−martensite (ε−m) along the crack propagation path. Additionally, the phase transformation of reversed austenite occurs at the crack nucleation stage during the impact process of both steels, which helps alleviate stress concentration and increases the energy required for crack formation. The primary reason for the higher strength of 4MnCM lies in the significant enhancement of precipitation strengthening effects through the precipitation of M6C, M23C6 and Nb/TiC co-precipitation with M6C.

Impact of tannery wastes on anaerobic co-digestion: enhancing biogas production and process efficiency

The study investigates the potential of anaerobic co-digestion (AcoD) as a sustainable solution for managing putrescible organic waste generated by leather processing. Three experiments were conducted to assess the impact of various tannery wastes, pretreatment methods, and waste combinations on methane production. Experiment 1 demonstrated that co-digesting tannery wastewater primary sludge (TWPS) and fleshings significantly increased methane yield compared to digesting TWPS alone, though the addition of chromium- and vegetable-tanned leather wastes decreased yield. Experiment 2 explored TWPS pretreatment methods and found that ultrasonic pretreatment increased soluble chemical oxygen demand (SCOD) but did not significantly improve methane yield, suggesting that pretreatment may not be necessary. Experiment 3 revealed that increasing the proportion of fleshings to TWPS resulted in higher methane yield, ranging from 226.52 mL/gVS with 6% fleshings to 395.71 mL/gVS and 538.34 mL/gVS with 12% and 20% of fleshings, respectively. Additionally, this increase in fleshings also led to a reduction in digester volume. These findings highlight the importance of AcoD in addressing both environmental and economic challenges in the leather industry.Graphical

Comparative analysis of mechanical properties of SiC particle addition on Al6061/Ni and Al6061/Cr metal matrix composites

This research paper investigates the mechanical characteristics of Al6061/Nickel (Ni) and Al6061/Chromium (Cr) metal matrix composites (MMCs) with varying proportions of Ni and Cr by weight. The proportions of Ni and Cr range from 0% to 2.7% weight. Experimental results reveal that the optimum mechanical properties are achieved at 1.8% weight for Ni. Subsequently, SiC (silicon carbide) particles are added to Al6061/Ni MMCs at varying weight percentages (0%, 1%, 3%, 5%, and 7%) to evaluate their impact on performance. The study demonstrates that the combination of 1.8% Ni and 7% SiC in Al6061 exhibits the most favorable properties. Tensile test is carried out with ASTM D 3552 standard; Flexural strength is assessed through ASTM D790, Microhardness by ASTM E384, and Impact strength by ASTM D256. Overall, Al6061/Ni MMCs exhibit superior mechanical performance compared to Al6061/Cr MMCs, with Al6061/Cr MMCs excelling in elongation, flexural strength, and impact strength. This investigation confirms that the addition of nickel and chromium to the Al6061 alloy induces structural modifications that enhance its mechanical properties. The findings provide valuable insights for optimizing the design and fabrication of MMCs for various engineering applications.

The Effect of Cr Addition on the Strength and High Temperature Oxidation Resistance of Y2O3 Dispersion Strengthened Mo Composites.

Y2O3 dispersion-strengthened Molybdenum (Mo) composites were prepared by the mechanical alloying of Mo and Y powders then consolidation by spark plasma sintering. The effects of Chromium (Cr) addition (0 wt. %, 5 wt. %, 10 wt. % and 15 wt. %, respectively) on the mechanical performance and high-temperature oxidation resistance of Mo-Y2O3 were investigated. The introduction of Cr had a significant influence on the mechanical property and oxidation resistance of the Mo-Y2O3 composite. The highest bending strength reached 932 MPa when the addition of Cr content was 5 wt. % (Mo-5Cr-1Y sample). This improvement is likely attributable to the dual mechanism of grain refinement and solid solution strengthening. Moreover, the Mo-5Cr-1Y sample showed the thinnest oxide layer thickness after high-temperature oxidation tests, and exhibited the best oxidation resistance performance compared with the other samples. First principle calculation reveals that Cr could improve the Mo-MoO3 interface bonding to prevent rapid spalling of the oxide layer. Meanwhile, Cr also facilitates the formation of the dense Cr2(MoO4)3 layer on the surface, which can inhibit further oxidation.

Physical properties of radiation dense reactive sintered borides

Reactive Sintered Borides (RSBs) were fabricated to investigate the effects of carbon and chromium content producing a series of samples referred to as Gen 2 RSBs. These RSBs were tested and evaluated for various mechanical (bulk moduli, fracture toughness, nano and micro-hardness) and microstructural properties. It is the first time when the correlation between different RSB phases and mechanical properties are understood in detail, along with the CALPHAD assessment of RSBs. CALPHAD was used to investigate the effect of sintering pressure and composition on melting point and liquid volume at sintering temperature and was critical in understanding of phase differences in Gen 1 and Gen 2 RSBs. Effects of carbon and chromium addition on mechanical and microstructural properties of RSBs were also investigated. Optimal second generation RSBs have fracture toughness of 7–10.1 MPa m0.5 and hardness of 15.9–19.1 GPa. RSBs with relative sintered density >98 % were achieved in this work. Combined X-ray diffraction and EBSD-EDX techniques were used to determine and confirm phase presence in RSBs. This work has demonstrated tractability and reproducibility of RSB materials with suitable mechanical properties for potential applications in spherical tokamaks alongside existing cemented tungsten carbides.

Corrosion of austenitic Fe-Ni based alloys with various chromium and aluminum additions in a carburizing-oxidizing atmosphere at 800ᵒC

Corrosion of austenitic Fe-Ni based alloys with various chromium and aluminum additions in a carburizing-oxidizing atmosphere at 800ᵒC

Mechanical, wear and corrosion behaviours of laser additive manufactured iron-based heterogeneous composite coatings for tillage tools

Steel is commonly used in engineering components, and it has a high tendency to wear and corrosion attacks when exposed to unfavourable working conditions. The use of chromium-vanadium-iron-rich carbide reinforced iron-based hard facings has become more important in improving the corrosion and wear resistance of such steel subjected to abrasive and impact conditions. In this study, the chromium-vanadium-iron carbide reinforced coatings were developed using in-situ by depositing FeCrV15+Cr powder through laser cladding on carbon steel. The influence of the reinforcement on the microstructure of the coating in relation to its laser processing condition and extra chromium addition was investigated. Furthermore, the effect of the coating's reinforcement on the hardness, microstructures, anti-corrosion, and anti-wear properties of the carbon steel used in tillage and mining operations was investigated. The result is a defect free deposits with a solid metallurgical attachment to the substrate and improved microhardness. FeCrV15 deposits had a wear-resistant (with a wear rate of 2.42 × 10−6 mm3/N/m) and anti-corrosion capability (with a corrosion rate of 0.001869 mm/yr) that were several folds higher than the steel substrate (with wear rate of 1.72 × 10−3 mm3/N/m and corrosion rate of 0.1168 mm/yr). The general grain refinement of the FeCrV15 deposits was richly enhanced in the iron base matrix. This resulted in outstanding wear and corrosion resistance attributed to the better production of VC–Cr3C2–Cr7C3 particles and better grain refinement of the microstructural formation.

Performance and properties evolution of near-term accident tolerant fuel: Cr-doped UO2

Chromium-doped UO2 fuel has received significant interest due to the ability for chromium to produce pellets with large average grain size (>30 μm), which has shown to increase fission gas retention during operation. Sintering of chromium-doped UO2 pellets was pursued with oxygen potential and sintering atmosphere controlled to tailor the final microstructure of the material. Chromium additions in this study ranged from 750 to 7800 ppm. Cr concentrations were studied pre and post sintering using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Effects of chromium content on lattice parameter and microstructure were examined with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Contraction of the UO2 lattice parameter was observed, as well as enlargement of grain size with increasing chromium content up to 4900 ppm Cr2O3. SEM indicated Cr incorporation within the matrix and the formation of chromium oxide precipitates throughout the microstructure at high Cr concentrations. Evaluation of thermophysical properties of Cr-doped UO2 pellets were conducted up to 1200 °C to illustrate their evolution with increased dopant concentration and microstructural changes. The results show that grain size is maximized at 52 μm with Cr2O3 concentration equal to 4900 ppm; however, grain size decreases at higher Cr2O3 concentrations. No significant changes were observed in specific heat capacity, linear thermal expansion, and coefficient of thermal expansion compared to undoped UO2. The thermal conductivity also decreased through the incorporation of Cr2O3 dopants above 750 ppm and is shown to be ∼15 % lower than reported UO2 values.

Evaluation of Microstructure and Abrasive Wear-Resistance of Medium Alloy SiMo Ductile Cast Iron.

Medium-alloy ductile iron with a SiMo ferritic matrix has very good heat resistance. The addition of chromium and aluminum also increases this resistance. This article presents the impact of chromium and aluminum on the structure of SiMo cast iron, especially their impact on the deformation of the spherical graphite precipitates and the formation of M6C and M3C2 carbide phases. These carbides are formed in a ferritic matrix or at the grain boundaries, resulting in increased hardness and a drastic reduction in impact strength. The article presents the influence of heat treatment on the material's microstructure and resistance to abrasive wear. Chromium and aluminum additions can also indirectly reduce the abrasive wear resistance of SiMo cast iron. The presented research shows the possibility of doubling the abrasive wear resistance of SiMo cast iron.

A new index to estimate the corrosion resistance of aluminium‐containing steel

AbstractA new index that estimates the corrosion resistance of aluminium‐containing steel is established and verified. It is based on the well‐known pitting resistance equivalent number (PREN) but accounts for aluminium additions. It is shown that aluminium enhances the corrosion resistance of chromium‐containing steel, with a coefficient of 5.2. The new corrosion resistance index (CRI) is as follows CRI = Cr + 3.3Mo + 16N + 5.2Al. A minimum of 4 wt% of chromium addition is needed. In addition, the atomic ratio of chromium to aluminium addition needs to be higher than 1, for this new index to be valid. This new index allows for simple alloy design guidelines for steel applications that require improved corrosion resistance. Analysis of the data from the literature shows that this index becomes inaccurate when the corrosion environment is in the presence of NaCl, and aluminium becomes less effective in enhancing corrosion resistance.

Effect of ultrafine-grained structure and chromium addition on corrosion resistance of Ni-Cr-Al alloys

The present work aims to understand the various scientific aspects related to the corrosion behavior of the ultrafine-grained (UFG) and coarse-grained (CG) Ni-(10,20)Cr-10Al (wt%) alloys in 3.5 wt% NaCl solution based on the passive layer formation on the alloys. In this regard, UFG and CG Ni-(10, 20)Cr-10Al (wt%) alloys were synthesized and characterized. Results of corrosion studies reveal that the UFG structure of the alloys is favorable to enhance the corrosion performance due to their high grain boundary density, which provides nucleation sites for rapid and effective passivation of the alloys by the formation of external Cr2O3 layer instead of mixed oxides/hydroxides. Besides, the Cr addition to the alloys also fosters the Cr-containing passive layer formation. The superior corrosion behavior of the UFG alloys is supported by scanning electron microscopy, electrochemical impedance spectroscopy, and Raman spectroscopy.