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Microstructure degradation and creep failure study of the dissimilar metal welded joint of heat-resistant steel and Inconel 617 alloy tested at 650 °C and applied stress range of 100-150 MPa
No full textThe advanced ultra-supercritical (A-USC) power plant system is anticipated to become India's next-generation base-load power station. To adopt AUSC technology, dissimilar welded joints (DWJs) between heat-resistant steels and the nickel-based alloys, using the nickel-based fillers, will need to be implemented. However, failure of dissimilar welded joints from P92 steel base metal or the heat affected zone (HAZ) has been commonly observed under high-temperature creep conditions. In the present study, the creep rupture behaviours and rupture mechanisms of DWJ between the Ni-based alloy Inconel 617 and heat-resistant P92 steel with Inconel 617 (ERNiCrCoMo-1) filler metal were investigated. Creep tests were conducted at 650 degrees C in the stress range of 100-150 MPa. To examine the creep rupture behaviour of the DWJ samples, optical microscopy (OM), scanning electron microscopy (SEM) and microhardness tests were performed. Cross-sectional images of the fractured creep specimens tested under various operating conditions revealed failures originating from distinct locations, including the P92 base metal and the inter-critical heat affected zone (HAZ). The specimen tested at 650 degrees C/150 MPa exhibited failure originating from the P92 base metal, whereas the specimen tested at 650 degrees C under the stress range of 100-130 MPa showed failure from the inter-critical heat affected zone (ICHAZ). The failure from P92 BM was primarily governed by plastic deformation, with the growth and coalescence of dimples ultimately resulting in trans-granular fracture. The specimens tested at 650 degrees C/100-130 MPa, which failed from the ICHAZ, exhibited a typical Type IV inter-granular failure. This failure mode is primarily attributed to matrix softening in HAZ, weakening of the boundaries, coarsening of the precipitates, and the evolution of intermetallic Laves phases. The specimen that failed in the stress range of 100-130 MPa exhibited a high density of microvoids in the ICHAZ, along with a few microvoids in the FGHAZ. The weld metal showed negligible degradation in microstructure, while the hardness study revealed a significant increase in hardness with an increase in rupture time, i. e., a decrease in applied stress and it was attributed to evolution of the new carbide phases in weld metal. Coarsening of the carbide precipitates was observed in each zone of the HAZ of P92 steel as well as in the base metal. The EDS study of the fracture tip and the FGHAZ/ICHAZ of the specimen that failed under stresses of 100 MPa and 120 MPa confirmed the evolution of intermetallic Laves phases. High magnification SEM images confirmed that triple boundaries are preferential locations for microvoid nucleation. The failed specimen showed the presence of microvoids near the carbide precipitates, with a large density of both coarse and fine precipitates confirmed all around and inside the microvoids. The ICHAZ and FGHAZ confirmed the formation of fine prior austenite grain boundaries (PAGBs) during the welding thermal cycle, which exhibited a lower density of carbide precipitates and this played a major role in Type IV failure
On improved inorganic gas-sensing characteristics of microwave-treated tungsten oxide quantum dots at room temperature
No full textTungsten oxide (WO3) based metal oxide semiconductor material has been conventionally used for sensing inorganic gases at elevated temperatures. However, in this study, the gas sensing performance of tungsten oxide-based sensors is evaluated at room temperature. In this study, WO3 quantum dots (QDs) are synthesized via the electrochemical method, followed by a microwave treatment to dehydrate them. The newly developed process is relatively less expensive and offers the flexibility to alter the structure in terms of phase, size, shape, and vacancy concentration. It is observed that electrochemical process parameters play an important role in phase evolution and control the oxygen vacancy concentration in the powder, which are essential for enhancing its gas sensing characteristics. Results showed an enhanced gas-sensing ability of WO3 QDs at room temperature toward inorganic gases, such as CO, NO2, NH3, and H2 when subjected to microwave treatment. The enhanced gas-sensing performance of microwave-treated WO3 QDs is attributed to its smaller size and high oxygen vacancy concentration. The minimum limit of detection values for CO, NO2, NH3, and H2 at room temperature using microwave-treated hydrated tungsten oxide QDs were 4.60, 1.5, 0.35, and 10.25 ppm, respectively
Recovery of calcite using eco-friendly bio-collector in the flotation of low-grade limestone
No full textLimestone flotation is a vital process in mineral processing, aimed at selectively separating valuable minerals such as calcite, from its associated gangue in the limestone matrix. The flotation of a low-grade limestone analyzing 41.78% CaO, 5.74% MgO, and 9.87% SiO2 by utilizing a new eco-friendly, plant seed oil processing industry waste-based fatty acid, as an anionic bio-collector for developing a sustainable process, was studied. A flotation concentrate of 59.94% weight recovery and analyzing 2.67% MgO, 49.92% CaO and 2.79% SiO2 could be obtained at 2.4 kg/t bio-collector dosage.
The flotation results indicated the selective recovery and enrichment of CaO and reduction of MgO and SiO2 content from the low-grade limestone thereby making it a suitable raw material for cement manufacturing. The study highlights the development and the effective utilization of industrial waste-derived, bio-based calcite collector that aligns with the growing emphasis on the broader industry trend toward more sustainable mineral processing practices
A review on assessment of ionic liquids in extraction of lithium, nickel, and cobalt vis-`a-vis conventional methods
No full textThis review discusses the extraction of critical metals (Li, Co, and Ni) using ionic liquids. Here, ionic liquids
act as solvents for the separation and extraction of metals. In addition to extraction, they can be used as
a lixiviant to leach out metals from spent lithium-ion batteries. Leaching and extraction of metals from
the leachate can be performed using a single ionic liquid solvent. Lithium, cobalt, and nickel have been
discussed in detail as per their reactivity towards an ionic liquid based on the extraction efficiency and
reusability of the ionic liquid. Recycling and reusability of ionic liquids are crucial parameters to be
considered while using them as solvents for extracting metals. Moreover, all the other methods such as
solvent extraction, ion exchange, ionic liquids, and DES-based separation of metals are compared with
respect to their extraction efficiency, cost-effectiveness, and reusability
Extractability and occurrence of rare earth elements in bottom ash through sequential leaching and pre-treatment
No full textUtilization of coal bottom ash (BA) produced by thermal power plants has been a national issue. Insufficient knowledge on the association of rare earth elements (REEs) with the parent aluminosilicate matrix of bottom ash limits its optimum utilization in commercial level. In the present study, we analyzed the distribution and occurrence modes of REEs within the bottom ash sample acquired from a power plant in India. The concentrations of major oxides were in the order of SiO2 > Al2O3 > Fe2O3 > TiO2 > K2O > CaO similar to MgO. The total concentration of REEs in the bottom ash sample was found to be 383 ppm where the concentration were in the order of Ce > Nd > La > Sc (for LREE) and Y > Dy > Er > Ho (for HREE). The total concentration of critical REE was 117 ppm and C-outl was deduced to be 0.84. Sequential extraction confirmed that about 80% of total REE remained embedded in the residual fraction. X-ray diffraction (XRD) analyses showed the presence of anatase/rutile/, hematite, mullite, quartz, calcite, and berlinite as major mineral phases. A comparative study on effects of multiple pre-treatments such as alkaline roasting (1:1 NaOH, 400 degrees C) and acid baking (1:1 h(2)SO(4) at 180 degrees C) as well as particle size alteration (75-250 mu m) was ascertained, where alkaline treatment was concluded to be optimum. The novelty of the present work lies in delineation of optimum pre-treatment of industrial bottom ash through sequential extraction aiming at improving the leaching potency of REEs using environment friendly organic acids
In situ synthesis of a photocatalyst using TiO2 QDs-immobilized functionalized galactomannan for degradation of organic pollutant
No full textTiO2 based photocatalysts are highly efficient systems in degrading organic contaminants. In the present work, an in-situ approach has been adopted to synthesize TiO2 quantum dots (QDs) with simultaneous grafting of methacrylic acid (MAc) on guar gum (GG), to develop a hybrid composite (GG-g-PMAc-@-TiO2 QDs) for photocatalytic degradation of toxic organic contaminant. The in-situ synthesis and proper dispersion of TiO2 QDs over polymer surface is aided by the stabilization through electrostatic interaction and hydrogen bonding between the acid functionality of the grafted PMAc chains and TiO2 QDs. The structural and morphological properties of GG-g-PMAc-@-TiO2 QDs have been thoroughly investigated by various characterization techniques. The HR-TEM analysis reveals the average particle size of TiO2 QDs is similar to 3.9 nm. The optical properties of the composite have been studied by UV, PL and TCSPC analyses. Moreover, the developed nanohybrid GG-g-PMAc-@-TiO2 QDs photocatalytically degrades ciprofloxacin (CIP) efficiently (similar to 94 % degraded within 3 h). The HR-MS analysis predicts the various degraded CIP fragments that have further been used to establish probable degradation mechanism
Real-Time In-Process Measurement and Control of Zinc Coating Weight: Assessing Eddy Current Sensor Proficiency in Industrial Applications
No full textThe investigation aims at evaluating the proficiency of an eddy current (ECT) sensor potential for in situ, real-time industrial applications. This sensor designed for in-process monitoring and control of zinc coating weight on GI wires, ranging from approximately 50-150 g/m2 expressed as grams per square meter (GSM). It is engineered to operate effectively in challenging industrial environments, providing immediate feedback during production, even at high speeds. In this study, an ECT sensor is configured in an encircling coil arrangement, consisting of three coils of which two transmitter coils are interconnected in a Helmholtz configuration, while the receiver coil is precisely positioned axially and concentrically between the transmitter coils. This design substantially extends the measurement region with a nearly constant magnetic field profile, making it particularly suitable for evaluating the weight of thin zinc coatings on the tested specimens. The superiority of this configuration is established through mathematical modeling, showcasing enhanced measurement accuracy and sensitivity, especially for evaluating the weight of thin zinc coatings on wires. This is further affirmed through validation and optimization via finite element method (FEM) simulations. In situ performance evaluation of the sensor system was conducted at an industrial installation, encompassing essential practical considerations, such as repeatability, reproducibility, and the influence of temperature fluctuations. The findings are in agreement with the chemical analysis (within +/- 5 %) stipulated by international regulations. The ability to consistently measure and record thin coating weight confers significant benefits, contributing to both zinc conservation and optimal quality control
Correlating Microstructure with Mechanical Properties for Different Regions of Dissimilar Metal-Welded Joints
No full textIn light water reactor of nuclear power plant, welded joint between dissimilar steels requires sufficient
reliability, ample efficiency, substantial operational life, and adequate safety. In the present investigation,
welded joints were produced between low alloy steel (SA 508 Gr.3 Cl.2) and 304LN austenitic stainless steel
(SA 312 Type 304LN) using INCONEL 82 (IN82) as both buttering material and weld metal. For one set of
joint, a post-weld heat treatment was carried out at pre-defined parameter. Owing to wide difference in
characteristics of these alloys, microstructural and mechanical properties exhibited substantial variation at
different regions of welded assembly. Portable automated ball indentation (PABI) technique was used to
evaluate the mechanical properties of various zones across the welded joint. Quantitative assessment of
microstructural features of the joint was performed by conventional microscopy and x-ray diffraction
technique and electron backscattered diffraction. Across fusion boundary, it was observed that the weakest
region was buttering material. The reason of low strength was attributed to low dislocation density, minimal
KAM value, and small microstrain along with moderate crystallite size. Strength of all zones across the
joint was reduced after heat treatment; however, the failure prone location was still within buttering
material. In this context, PABI with x-ray diffraction and EBSD experimentation endorsed the potential of
the combined technique for reliable evaluation of dissimilar metal-welded joint
Study research protocol for Phenome India-CSIR Health Cohort Knowledgebase: A prospective multi-modal follow-up study on a nationwide employee cohort
No full textPredicting individual health trajectories based on risk scores can help formulate effective preventive strategies for diseases and their complications. Currently, most risk prediction algorithms rely on epidemiological data from the Caucasian population, which often do not translate well to the Indian population due to ethnic diversity, differing dietary and lifestyle habits, and unique risk profiles.
In this multi-center prospective longitudinal study conducted across India, we aim to address these challenges by developing clinically relevant risk prediction scores for cardio-metabolic diseases specifically tailored to the Indian population. India, which accounts for nearly 18% of the global population, also has a significant diaspora worldwide. This program targets longitudinal collection and
bio-banking of samples from over 10 000 employees both working and retirees of the Council of Scientific and Industrial Research and their spouses, with baseline sample collection already completed. During the baseline collection, we gathered multi-parametric data including clinical questionnaires, lifestyle and dietary habits, anthropometric parameters, lung function assessments, liver elastography by Fibroscan, electrocardiogram readings, biochemical data, and molecular assays, including but not limited to genomics, plasma proteomics, metabolomics, and fecal microbiome analysis. In addition to exploring associations between these parameters and their cardio-metabolic outcomes, we plan to employ artificial intelligence algorithms to develop predictive models for phenotypic conditions. This study could pave the way for precision medicine tailored to the Indian population, particularly for the middleincome strata, and help refine the normative values for health and disease indicators in India
Impacts of powder size on amorphous-crystalline transition behaviours in gas atomized Fe-rich alloy powders
No full textThe present research is focused on the development of Fe-based bulk metallic glassy alloy powders by gas atomization
(GA) technique, for their utilization in additive manufacturing. The pre-alloyed ingots are gas atomized under nitrogen gas pressure, producing the powders with a wide size range of 1–300 μm. After sieving analysis, it was found that 50 and 90 % of powders were below the 47 and 91 μm size ranges, respectively. Scanning electron microscopy (SEM) reveals high sphericity, smooth surface finish, and satellite-free outer surface characteristics in the developed GA powders. The finer powders (50 μm size). The powders below the 63 μm size range are examined as fully amorphous structures through an X-ray diffraction (XRD) pattern. The thermograms also explain high amorphicity (~ 90 %) for these powders (< 63 μm size), evaluated by differential scanning calorimetry (DSC). The soft magnetic properties are obtained with an effective variation with the
change of powder particle size. The developed amorphous powders have the potential for the additive manufacturing of soft magnetic machine components