8369 research outputs found
Sort by
Structural phase transformation in single-crystal Fe–Cr–Ni alloy during creep deformation using molecular dynamics simulation and regression-based machine learning methodology
No full textManipulation of creep properties and microstructural transformations at different temperatures and applied stresses depicts huge importance for the design and development of various grades of metals and alloys. Therefore, we have considered nano-size face-centered cubic (FCC) single crystal of Fe–Cr–Ni alloy to investigate creep response under a wide range of temperatures and pressure through molecular dynamics (MD) simulation and regression-based machine learning methodologies. From MD simulation, we have found the evolution of multiple rectangular blocks of body-centered cubic (BCC) crystal and layered FCC and HCP crystal during creep deformation under externally applied tensile load. Rectangular blocks and layered crystal structures corroborated with the secondary and tertiary stages of creep curves of Fe–Cr–Ni alloy, respectively. Machine learning methodology provides information to predict the creep properties and correlates data obtained from MD simulations. The results of this investigation will provide an understanding of the creep properties during thermal and mechanical processing, which will help to improve the performance of various grades of steel and other alloy
Determinant analysis of oil agglomeration of coal fines using multiple regression and neural network models
No full textOil agglomeration has gained importance owing to its simplicity and efficiency in beneficiating coal fines. In this study, high ash coal samples taken from six mines in India were put through an oil agglomeration process to investigate the usage of castor oil or blend of castor and turpentine for recovery of coal fines from coal-water slurry. The performance of the process has been evaluated based on ash rejection [AR (%)] and yield (%). Various Statistical analyses were carried out to investigate the role of various process parameters, such as PD, OD, AT, and oil-type on AR (%) and yield (%). Step-wise regression was performed for development of prediction model for AR (%) and yield (%). Determinant analysis was performed using general linear model (GLM). Our findings indicate that pulp density was the strongest determinant for AR (%), followed by oil dosage and agitation time. Similarly, oil dosage was the primary determinant for yield (%), followed by pulp density and agitation time. Sensitivity analysis was also carried out using artificial neural network (ANN) and the results in respect AR (%) revealed that agitation time was the most important predictor followed by pulp density and oil dosage
Measurement of Mid Spatial Frequencies of Diamond Turned Optics by using Dual-mode Snapshot Interferometry
No full textThe measurement of mid-spatial frequency (MSF) in ultra-precision machining is crucial for assessing the quality and performance of machined surfaces. MSF refers to the frequency range of surface irregularities between low-frequency form errors and high-frequency roughness. The sources that contribute to MSF errors during diamond turning are vibrations and dynamic instabilities, tool wear and deflection during cutting, inconsistent feed rates, variation in material properties, incorrect machine settings/process parameters, material removal mechanism employed (e.g., ductile or brittle removal). Controlling & measuring mid-spatial frequencies in the diamond-turning process is essential for meeting stringent optical specifications in various applications, such as lens manufacturing for imaging systems, telescopes, laser systems, etc. Inspecting MSF errors offline or after the manufacturing process is a common practice in the quality control of optical surfaces. However, there is a growing interest in incorporating on-machine metrology to detect and address MSF errors. One of the latest developments is a dual-mode on-machine metrology (OMM) system that simultaneously measures surface form and roughness without requiring the optical path's reconfiguration to switch between laser interferometer mode and LED interference microscopy mode. This study uses OMM to study the influence of process parameters and their impact on the mid-spatial frequencies during diamond turning. OMM provides real-time feedback, which helps in adjusting machining parameters to correct deviations and maintain the desired mid-spatial frequencies
Production and recycling of blast furnace slag: A life cycle assessment approach in India
No full textThis article investigated the cradle-to-gate environmental impact of granulated blast furnace slag (GBFS) produced in the steel industry and replacement of blast furnace (BF) slag (50%) in place of clinker in Portland slag cement using GaBi software (Indian extension database). In case of GBFS production, maximum burden on the environment is due to BF slag production and the amount of electricity consumed (161 MJ/ton) during the granulation process. The influence of electricity sources on GBFS production was studied via scenario analysis. For investigation, solar and thermal electricity mixes were considered in 50:50 and 75:25 ratios. For the 75:25 ratios, the abiotic depletion potential (fossil), acidification, eutrophication, global warming, and human toxicity potential show a decreasing trend of approximately 45%, 49%, 48%, 46%, and 41%, respectively. The scenario analysis of BF slag transportation (from 100 to 750 km) demonstrates a negative impact due to fuel. The results quantitatively confirm that the addition of GBFS can lower the overall impact for construction and steel industries
Efect of inter‑critical annealing atmosphere on microstructure and subsequent corrosion behavior of hot‑dip galvanized Mn containing high‑strength steel
No full textA systematic study is performed on the development of hot-dip galvanized coatings on a Mn-containing high-strength steel sheet by varying the dew point (− 50, − 10, and +10 °C) during inter-critical annealing of the steel strip at 800 °C. It also studies the efect of dew point on the corrosion behavior of the coatings in freely aerated 3.5 wt% NaCl solution. The reducing gas atmosphere consists of 95% N2 and 5% H2, where inter-critical annealing is carried out. Surface oxidation of the steel has a strong efect on the development of sound coating. A defect-free adherent galvanized coating is obtained on the annealed steel surface at a fxed dew point of +10 °C, and it is attributed to the fne and continuous compact Fe-Al crystals compared to galvanized coatings produced at other dew points as well as the highest atomically dense (0002) basal plane. This also leads to the lowest corrosion rate (~0.164 mm y−1, where mm and y stand for millimeter and year, respectively) of the galvanized coating produced at a dew point of +10 °C when compared with galvanized coatings produced at dew points
of − 50 °C (~0.279 mm y−1) and −10 °C (~0.259 mm y−1). The lowest corrosion rate of the galvanized specimen developed
at +10 °C dew point can be attributed to the uniform and defect-free coating surface, together with the dominance of the more atomically dense (0002) basal plane
Improving the energy efficiency in a walking hearth type reheating furnace by energy balance method and optimizing the resources
No full textMost metal industries use reheating furnaces (RHF) for their finishing operations. This RHF is highly energyconsuming equipment that heats the material inside the chamber for rolling or shaping using the by-product gases, natural gas, or oil as fuel. It is necessary to minimize or optimize the fuel consumption to the extent possible. By analyzing the plant operating data, plant measurements, and energy balance calculation, this work aims to determine the potential for decreasing the fuel consumption of a billet reheating furnace. Predictions are made by modeling operating data to reveal the hidden problems and uncover underlying issues. The study results in increasing productivity by 11 % while oil consumption was reduced by 14 %. These actions significantly decreased carbon emissions considerably and generated significant cost savings
Development of octahedral shaped Zn2TiO4 loaded Ti3C2-TiO2 ternary composite with excellent photocatalytic efficiency
No full textThe development of highly efficient and stable earth-abundant photoanode materials for photoelectrochemical
water splitting is crucial for a sustainable energy economy. Being earth-abundant, 2D Ti3C2 MXenes have recently emerged as promising candidate for efficient photocatalytic performances. However, pristine Ti3C2and its composites suffer from poor electron–hole separation and fail to prevent the spontaneous recombination process due to the poor conductivity derived from the serious agglomeration of MXene sheets during processing. Therefore, suitable heterojunction engineering of the MXene based composites is required for their efficient photocatalytic performances. Hence, in this work, we have developed a Ti3C2-TiO2 and octahedron-shaped, nanosized Zinc titanate (Zn2TiO4) based ternary nanocomposite with optimized composition via a simple process of alkalization followed by hydrothermal. As-synthesized Ti3C2-TiO2/Zn2TiO4 (1:0.5) nanocomposite shows
a 3.7 fold augmentation in photocurrent density as compared to alkali treated Ti3C2-TiO2 at a potential of 0.9 V
vs Ag/AgCl resulted due to the facile charge transfer evidenced from its impedance analysis having lowest charge
transfer resistance. Furthermore, the Mott-Schottky measurements reveal that the as-synthesized nanocomposites
possess n-type semi conductivity and the charge carrier concentration of Ti3C2-TiO2/Zn2TiO4 (1:0.5) is almost 5.2
times higher than that of alkali-treated Ti3C2-TiO2. This work may inspire more excellent work on developing
MXenes-based photoanodes
A Comprehensive Review on Occurrence and Processing of Phosphate Rock Based Resources- Focus on REEs
No full textIn general, the phosphatic rock contains around 0.05 wt% rare earth elements (REEs). The global com-mercial phosphatic rock output is anticipated to obtain 250 million tons per year, making phosphate rocks a significant source of REEs. The review discusses the geological aspects of phosphate rocks, their availability, and methodologies to convert them to phosphoric acid and ultimately to phosphogypsum. Phosphogypsum (PG) is a high-volume by-product of phosphate-based chemical industries that produce phosphoric acid. Because of the low radioactivity of radionuclide contaminants, roughly 85% of PG is stored in open fields. These PG stacks require enormous land areas, cause substantial upkeep expenses, and may create major environmental damage. Apart from the detailed analysis of metal worth in phosphogypsum, the efforts put forth by researchers in recovering valuable rare earth elements from PG have been discussed. Additionally, the processes for metal separation and purification are also discussed in vogue
Effect of hold-type on cyclic life and microstructural evolution of an austenitic stainless steel
No full textThe present work investigates the effect of different type of hold on the change in microstructure and cyclic life. i.
e., number of cycles to failure of the 304LN grade austenitic stainless steel at an elevated temperature. The straincontrolled low cycle fatigue and creep-fatigue interaction tests were carried out in air at 540 ◦C for constant total
strain amplitude levels of ± 0.5 % and ± 0.7 %. The duration of hold-time was maintained at a constant level of
600 s at peak tensile, compressive and both peak tensile-compressive strain during different creep-fatigue
interaction tests. Due to incorporation of creep damage, the cyclic life of the creep-fatigue interaction-tested
samples has been found to be lower than that of the low cycle fatigue-tested samples. The tensile-hold appears to
have maximum impact on reduction in cyclic life during creep-fatigue interaction tests followed by tension compression hold and compressive hold. The scanning electron microscopy and electron back scattered
diffraction analyses of creep-fatigue interaction-tested samples have revealed that the grain size coarsening,
reduction in twin boundary fraction and increase in average Kernel Average Mis orientation are the key factors in
reduction of cyclic lif
Heat Transfer and Fluid Flow During Laser Powder Bed Fusion of SS316L Stainless Steel
No full textPowder bed fusion using a laser-based (PBF-LB) process offers design freedom with an acceptable surface finish in several industrial applications. The judicial selection of the process parameters in the PBF-LB process can result in better performance of the additively manufactured products. The bead shape and size obtained in the PBF-LB process depend on the melt pool dimensions, while experimentally investigating the melt pool to understand the effect of PBF-LB process parameters is expensive and exhausting. Therefore, in the present study, melt pool dimensions are numerically envisaged for different process parameters to comprehensively understand the effect of various process parameters on the temperature distribution and molten pool size during PBF-LB of SS316L alloy. In this regard, a three-dimensional heat transfer analysis using finite element method (FEM) is attempted, and furthermore, the heat and mass transfer phenomenon in the molten pool during solidification is also analyzed utilizing finite volume method (FVM). A systematic comparison of the simulated results obtained from both methods is carried out in detail to understand the need to opt for FEM or FVM approach in predicting molten pool characteristics. The numerically predicted molten pool size is in good agreement with the experimental results