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Cathodic corrosion induced selective nano-crystallization of Nickel oxo/ hydroxo complex on (NiFeCr)SiB amorphous ribbon for alkaline oxygen evolution reaction and methanol oxidation reaction
No full textThe study focuses on the development and optimization of (Ni87Fe4Cr9)78Si8B14 amorphous ribbons as selfsupported electro-catalysts for oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). Electro-catalytically active nano alpha-Ni(OH)2 phase (5-10nm) was generated in the amorphous ribbon surface through potentiostatic cathodic corrosion for different time intervals (0-120 min). The X-ray diffraction and scanning electron microscopy results shows the favourable occurrence of dense nanocrystallization of alpha-Ni(OH)2 between 45 and 90 min of corrosion time. For OER in 1 M KOH, the 60-min surface modified ribbon exhibits an overpotential of 295 mV at 10 mA/cm2 current density and tafel slope of 51 mV dec-1. In case of MOR in 1 M KOH +1 M MeOH, the 90-min corroded ribbon shows lowest potential of 1.38 V vs RHE, at 10 mA/cm2 and tafel slope of 34 mV dec-1. In addition to superior electro-catalytic activity, the optimal surface-modified ribbons show superior long-term stability for OER and MOR studies, indicating its potential application in hydrogen generation and direct methanol fuel cell
Understanding the Formation Mechanism of Al-Rich Interfacial Layer during Galvanizing of Cu Pre-coated High-Strength Steel Sheet
No full textThis work aims at understanding the formation of a beneficial thin continuous aluminum (Al)-rich interfacial layer with uniform distribution of fine equiaxed Fe-Al crystals formed at the substrate/coating interface during the initial stages of interfacial reactions as well as hindrance of Fe dissolution in Zn layer as soon as copper (Cu) pre-coated high-strength steel substrate is immersed into the molten zinc (Zn) bath containing 0.2 wt.% Al. Pre-coated Cu does not allow the immediate interaction and interdiffusion of Fe and Zn because of the positive heat of mixing between Fe and Cu. As the Cu dissolves in liquid Zn, counterdiffusion of Al and Zn toward the steel interface allows Fe to react with Al and Zn forming the thin Fe-Al
inhibition layer with finer equiaxed grains. Moreover, dissolved Cu in the Zn layer would also prevent Fe diffusion in Zn in the time span during dipping, which is beneficial. Atom probe tomography (APT) analysis at the substrate/coating interface location reveals the presence of 56.22 ± 1.36 at.% Al, 35.01 ± 1.31 at.% Fe, 6.33 ± 0.66 at.% Zn, and 0.032 ± 0.01 at.% Cu, similar to the intermetallic compound of Fe2Al(5-x)Znx, as well Cu in the Zn layer supporting the above reasoning
Beneficiation of lithium bearing pegmatite rock: a review
No full textThe need for lithium in energy storage systems has risen dramatically due to the development of renewable energy technology, portable devices, and electric cars. The current review focuses on the existing worldwide resources of lithium ore, along with the production, demand, and mineralogy of lithium-bearing minerals, in addition to lithium recovery from hard pegmatite ore using different bene-ficiation techniques. Lithium ore is beneficiated using various methods, including magnetic separation, gravity concentration, electrostatic separation, and flotation to separate gangue minerals. Flotation is the most frequently utilized beneficiation technique. It is found that gravity concentration and flotation are the main beneficiation methods used in many plants around the world. In flotation, reagent chemistry, surface properties, and water quality were critical in spodumene’s efficient recovery. A summary of several reagent regimes, surface properties, flotation conditions, and prospective future studies for technical viability are provided. The current review paper also discusses the beneficiation flowsheet widely used to recover spodumene, lepidolite, and petalite from pegmatite ore. Also, it is tried to discuss the key future research areas along with the cost economics aspect of processing such ore deposits to recover lithium
Sour Service Domains of 13Cr Martensitic Stainless Steels: A Review of State-of-Art Knowledge vis-à-vis ANSI/NACE MR0175/ISO 15156
No full textHydrocarbons, water, carbon dioxide, hydrogen sulfide, chloride, high temperatures, and pressures are all involved in oil and gas production. Thus, corrosion, particularly sulfide stress cracking (SSC), poses a great threat to the integrity of well components such as tubing, casing, packer, and wellhead assembly. Sometimes, SSC can lead to catastrophic failures and must be addressed due to operational security and environmental concerns. Localized corrosion, including SSC, can be reduced greatly with the appropriate material selection and optimization of critical operational parameters. The material selection is performed according to service environments vis-a-vis mechanical/ metallurgical attributes of the alloys as prescribed in standards such as API 5CT and ANSI/NACE MR0175/ISO 15156. Currently, corrosion-resistant alloys (CRAs) such as martensitic and duplex stainless steels, nickel, titanium and other precipitation hardened alloys are available and used in oil and gas industries because of their superior mechanical and corrosion properties. Owing to the operating environmental reasons, designer often opt for more expensive CRAs as compared to relatively less expensive materials which fall close to the performance boundary of materials selection criteria, thereby increasing overall cost of crude oil production. Thus, there is a paramount requirement to ascertain the candidate materials appropriately without bearing the cost penalties of over-specifications or the performance shortfalls of under-specified alloys when new fields are discovered. In this paper, the application domains of 13Cr martensitic stainless steels are reviewed vis-a-vis limits prescribed in ANSI/NACE MR0175/ISO 15156 standard. The paper will aid in the selection of cost-effective materials for oil and gas production when temperature, pressure, hydrogen sulfide concentration, pH, and salinity vary in different directions and cannot be well defined within standard limits
Comparative interplay of C and Mn on austenite stabilization and low temperature impact toughness of low C medium Mn steels
No full textTo expand the use of medium Mn steels for the production of automotive and structural components intended for cryogenic applications, the present study focuses on attaining an enhanced low temperature impact toughness in two inter-critically annealed medium Mn steels with varying C and Mn contents without sacrificing the strength. In both 'low-C, high-Mn' and 'high-C, low-Mn' steels, the key role in regulating the impact toughness is mainly attributed to the volume fraction of stable retained austenite. Mn is found to stabilize austenite more effectively than C while allowing the attainment of near-equilibrium composition. Except for the 'low-C, high-Mn' steel, inter-critically annealed at lower temperature, Mn redistribution occurs in other samples, leading to a reduction of stable austenite fraction. The filmy shaped Mn enriched retained austenite is more thermally and mechanically stable in 'low-C, high-Mn' steel sample on inter-critical annealing at lower temperature than the other samples. The presence of fine dispersion of the filmy austenite at various substructural boundaries of 'low-C, high-Mn' steel after low temperature inter-critical annealing results in significant structural (Bain width) refinement and thereby, remarkably improves its impact toughness
The effects of microstructure and temperature on the deformation heterogeneities and fatigue behavior of a Ni-based superalloy
No full textThis research investigates the coupling effect of microstructure and temperature on the fatigue performance of an equiaxed Ni-base superalloy, EA, at design-significant temperatures (750-930 degrees C) for different strain amplitudes (Delta epsilon/2). It is observed that distinguishing damage features (specific to the temperature and Delta epsilon/2) remarkably affect the extent and distribution of strain localization, leading to the divergence in associated fatigue behaviour. The strain is uniformly distributed at lower Delta epsilon/2 for all temperatures. Compared to the 850 and 930 degrees C, the strain localizations at 750 degrees C are more effectively alleviated, accounting for the highest fatigue life. Moreover, this alloy exhibited a bilinear Coffin-Manson (C-M) relationship. It is ascertained that the strain localization resulting from the dislocation and precipitates (gamma ', Cr6C23, and gamma-gamma ' eutectic) interactions are mainly responsible for the dual-slope C-M behaviour
Limitations Associated with Proximate Analysis-Based Gross Calorific Value Modeling for Coals
No full textThis study aims to investigate the limitations associated with proximate analysis-based gross calorific value (GCV) modeling for coals. Toward this, a dataset comprising proximate analysis and GCV data of 4792 coal samples collected from various Indian coal basins was generated, and then a GCV prediction model was developed using the popular multivariate linear regression (MLR) technique. Although the developed model appeared to be acceptable in terms of a prediction R2 value of 0.934, through rigorous statistical analysis, it has been shown that grade misclassification and source-specific biases are inherent limitations associated with such GCV prediction models. It was found that the grade classification accuracy associated with a GCV prediction model was inversely and linearly proportional to the model's associated mean absolute error (MAE) value. It has further been demonstrated that even well-validated GCV prediction models available in literature may perform sub-optimally when utilized for grade classification tasks. The analysis presented in this study also confirms that a source-specific bias can be introduced in the GCV prediction models developed using coal samples from varied geographical sources. It has further been shown that the incorporation of a categorical representation of the sample sources in the GCV prediction model could successfully eliminate the source-specific biases
Understanding the phase stability in a multi-principal-component AlCuFeMn alloy
No full textMethod(s) that can reliably predict phase evolution across thermodynamic parameter space, especially in complex systems, are of critical significance in academia as well as in the manufacturing industry. In the present work, the phase stability in an equimolar AlCuFeMn multi-principal-component alloy (MPCA) was predicted using complementary first-principles density functional theory calculations and ab initio molecular dynamics (AIMD) simulations. The temperature evolution of completely disordered, partially ordered, and completely ordered phases was examined based on the Gibbs free energy. Configurational, electronic, vibrational, and lattice mismatch entropies were considered to compute the Gibbs free energy of the competing phases. Additionally, elemental segregation was studied using AIMD. The predicted results at 300 K align well with room-temperature experimental observations using x-ray diffraction and scanning and transmission electron microscopy on a sample prepared using commercially available pure elements. The adopted method could help in predicting plausible phases in other MPCA systems with complex phase stability
Neutral pH Fenton and photo-Fenton activity of Mo-doped iron-pyrite particles
No full textLow H2O2 utilization efficiency for hydroxyl radical generation, acidic pH, and recyclability are critical limitations of heterogeneous Fenton and photo-Fenton catalysts. The present research shows that the optimum Mo doping of FeS2 particles can largely alleviate these catalysis constraints. A solvothermal protocol was followed to prepare polyvinyl pyrrolidone (PVP) stabilized FeS2 and Mo-doped FeS2 particles. XRD observations showed that Mo doping increases the lattice parameters of FeS2. The band gap of the Mo-doped FeS2 particles decreased to 1.58 eV from the 2.24 eV value exhibited by pure FeS2 particles. Structural and electronic structure DFT calculations support these results. The Fenton and photo-Fenton p-nitrophenol (PNP) degradation at neutral pH on PVP-stabilized Mo-doped FeS2 and FeS2 particles were examined. The photo-Fenton results were substantially better than under Fenton conditions. The best PNP degradation photo-Fenton turnover frequency (TOF) recorded was 254.50 mu mol g-1 min-1 on the PVP stabilized 4% Mo-doped FeS2 sample. The Mo-doped FeS2 catalysts were stable under photo-Fenton recycling, and the H2O2 (1.66 mM) required for these reactions was significantly lower than most reports (30-6000 mM). Given the economic importance of the latter in Fenton/photo-Fenton reactions, H2O2 normalized turnover frequency (13.85 and 153.31 mg-1 min-1 L for Fenton and photo-Fenton) values were used to evaluate catalytic activities. Mo-doping enhances FeS2 photo-Fenton activity and recyclability at neutral pH by effective Fe3+ to Fe2+ conversion
Environmental Impact Assessment in the Entire Life Cycle of Lithium-Ion Batteries
No full textThe growing demand for lithium-ion batteries (LIBs) in smartphones, electric vehicles (EVs), and other energy storage devices should be correlated with their environmental impacts from production to usage and recycling. As the use of LIBs grows, so does the number of waste LIBs, demanding a recycling procedure as a sustainable resource and safer for the environment. This review paper analyses and categorizes the environmental impacts of LIBs from mining their constituents, their usage and applications, illegal disposal, and recycling. Compared to recycling, reusing recovered materials for battery manufacturing would lessen the environmental footprints and reduce greenhouse gas emissions (GHG) and energy consumption. Thus, to prevent pollution and safeguard the environment, it is necessary to consider recycling spent LIBs and improving production and disposal methods. The present study offers a comprehensive overview of the environmental impacts of batteries from their production to use and recycling and the way forward to its importance in metal replenishment. The life cycle assessment (LCA) analysis is discussed to assess the bottlenecks in the entire cycle from cradle to grave and back to recycling (cradle)