8369 research outputs found
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Rapidly quenched magnetic materials for functional and sensor applications
No full textRapidly quenched (RQ) amorphous / nanostructured materials have been addressed in relation to their properties targeted towards potential applications. Quenching techniques like melt spinning and in-water quenching for production of these materials in the form of ribbons and microwires production respectively have been addressed. CoFe-based microwires exhibited interesting giant magneto-impedance (GMI) behviour and was used in development of GMI sensor for detection of carburization in austenitic stainless steel. Efforts have been laid on the production of Fe-based magnetostrictive amorphous ribbons and their potential use in magnetostrictive sensor (MsS) for generation of guided waves for detection of defects in pipes. Compositional tailoring has also been carried out in amorphous / nanostructured ribbons to raise the saturation magnetization beyond 1.6 Tesla. Some of these ribbons have also been found to manifest interesting electromagnetic interference shielding effectiveness (EMI SE) properties
Estimation of the Fluid Velocity Profile in the Stratification Zone of a Falcon Concentrator
No full textThe Falcon concentrator is capable of separating minerals in fine size classes based on their differential density. Separation of mineral particles depends upon the fluid flow characteristics and relative movement of particles in a fluid. In the present study, a fluid flow characteristic inside the Falcon concentrator was established through experimentation and modeling. The Falcon concentrator has two fluid entry points: (a) Fluid entering through gravity assisted feeding system and (b) Fluid entering through the fluidized hole on the concentrator wall. In order to identify the role of fluid entering the concentrator, a tracer was injected into the system. As per the tracer based experimentation, it was established that fluid entering through the gravity based feeding system is responsible for thin flowing film formation in the stratification zone where particles are stratified based on their relative density. The momentum balance and continuity equations were simplified for a high centrifugal force field, and the fluid velocity profile was estimated inside the thin flowing film. Estimated fluid flow profiles will help to simulate the particle trajectories inside the Falcon concentrator. The influence of rotational speed, fluid flow rate, and cone angle on the fluid velocity profile were investigated. Fluid thickness over the concentrator wall is also estimated, and it is typically of the order of ~150–200 μm
Structural Evolution of Iron–Copper (Fe–Cu) Bimetallic Janus Nanoparticles during Solidification: An Atomistic Investigation
No full textBimetallic nanoparticles consist of two different metallic elements, which have attracted enormous interest from both the scientific and industrial points of view. Bimetallic nanoparticles could demonstrate not only a combination of properties related to the existence of two individual metals but also innovative properties due to association of two metals. Bimetallic nanoparticles have extensive applications in the broad area of metallic catalysts, electrochemicals, biosensors, and so forth. In the present investigation, iron–copper (Fe–Cu) bimetallic nanoparticles are designed and characterized using extensive molecular dynamics simulations. The Fe–Cu bimetallic nanoparticles can be oriented in random alloy, core–shell, Janus, and other morphologies, depending on their composition and thermal processing. Fe–Cu bimetallic nanoparticles clearly show a Janus morphology for the case of comparatively slower cooling rate. Face-centered cubic, body-centered cubic, and hexagonal close-packed structures are observed in the crystalline phase of Fe–Cu bimetallic nanoparticles. The phase transition from the liquid to the crystalline structure is extensively influenced by the cooling rate. Adaptive common neighbor analysis, radial density distributions, and potential energies have been used to characterize the Fe–Cu bimetallic nanoparticles. The present theoretical investigation on bimetallic nanoparticles will enhance our understanding associated with the physical phenomena for the development of various types of metallic nanoparticles
Optimization of electrospinning process & parameters for producing defect-free chitosan/polyethylene oxide nanofibers for bone tissue engineering
No full textChitosan (CS) nanofibers were electrospun from aqueous chitosan solution using concentrated acetic acid solution as a solvent. Polyethylene oxide (PEO) with varying weight content from 10- 60 wt% was mixed with chitosan solution that acted as a plasticizer to improve spinability of the prepared chitosan solution. With the increase in PEO content from 10-50 wt% the viscosity of the resultant CS/PEO solution was decreased from 0.938 Pa-s to 0.272 Pa-s, whereas higher the concentration of acetic acid lower was the surface tension of resultant chitosan solution. It was found beadless nanofibrous chitosan mat was obtained not less than 85% acetic acid concentration, 50 wt% PEO and at 0.2 wt% NaCl and 5 wt% total polymer concentration. From field emission scanning electron microscopy (FESEM) investigation, it was observed that chitosan fibers with an average diameter of 149 nm were produced at an applied voltage of 22.5 KV, while that varied between 17.5- 25 KV. On the other hand, a minimum of 110 nm of average diameter chitosan nanofiber was obtained at a needle tip to rotor collector distance of 15 cm by the method of electrospining. In terms of solution flow rate, 0.4 mL/h was found to be optimum in obtaining defect-free electrospun fiber with lower average diameter. As a whole, smooth and uniform chitosan nanofibers were obtained from 50/50 CS/PEO solution prepared by using 90% acetic acid and electrospun at 20 kV applied voltage, 15 cm needle tip-to- rotor collector distance with 0.2 mm inner diameter needle and 0.4 mL/h feeding rate. After crosslinking with 1 wt% glutaraldehyde (GTA), the ultimate tensile strength and Young's modulus of chitosan scaffold increased upto 9.47 MPa and 147.75 MPa respectively. From MTT assay and alkaline phosphatase expression analysis upto 11 days of cell culture period it was evident that thus prepared electrospun CS scaffolds supported MG 63 cell proliferation and its differentiation into mature osteoblast
The Ignitability, Fuel ratio and Ash Fusion Temperatures of Torrefied Woody Biomass
No full textThe impact of torrefaction temperature on the ignitability, fuel ratio and ash fusion temperatures of two tropical deciduous woods (Teak and Melina) were investigated in a setup of tubular furnace. The properties considered are calorific value, fuel ratio, ignitability index, ash compositions and ash fusion temperatures of the biomass. Six different temperatures (220, 240, 260, 280, 300 and 320 °C) at 60 min reaction time were considered. The results indicated that as torrefaction temperature increased, the calorific value, fuel ratio and ignitability index of the biomass also increased. The ignitability index of biomass (40–63) was better than the value (35) recommended for fuel applicable in thermal plants for power generation. The ash compositional analysis revealed that there was no variation in the quantity of SiO2, Al2O3, CaO along with other minerals for the raw and torrefied biomass. This implied that the temperature up to 320 °C has no significant impact on the compositions of biomass ash during torrefaction. The ash fusion temperature test showed that the biomass ash softens at 1200 °C and finally fused at 1300 °C. The study concluded that an increase in torrefaction temperature increases the thermal properties of the torrefied biomass without affecting the compositions of biomass ash or lowering the ash fusion temperatures
High Entropy Alloys: An Overview on Current Developments" in the book "High Entropy Alloys: Innovations, Advances, and Applications
No full textHigh entropy alloys, being one of the advanced engineering materials, containing at least five principal elements with configurational entropy more than 1.5R, have received widespread consideration from both academia and industries due to their unique properties. Although a lot of work has been published on these materials, a thorough understanding of the basics and critical interpretation of the recent findings are still eluding researchers, which are a necessity for further advancement in high entropy alloys. Therefore, the present chapter provides a comprehensive review on current developments in high entropy alloys with a special emphasis on the thermodynamics, alloy design, and microstructure-property relationship. In terms of thermodynamic consideration for phase prediction, the importance of enthalpy and non-configurational entropy, in contrast to the earlier belief of the major role of configurational entropy in the stabilization of any phase, has been discussed in light of the recent studies. The composition of these alloys plays a pivotal role in determining the physical and mechanical properties of these alloys. Therefore, to reach to the right combination of alloying elements for desired microstructure and superior properties, various approaches are considered for designing the high entropy alloys in the past. These have been discussed in detail. As there have been a considerable number of experimental studies on high entropy alloys, a large set of data on composition, process route, and tensile properties was collected from the recent literature and was systematically analyzed to highlight the effect of individual alloying addition and processing route on microstructure evolution and tensile properties at the room, sub-zero, and high temperatures. The analysis shows exceptional tensile properties for high entropy alloy at sub-zero and high temperature, in contrast to available structural alloys
Real-Time Parametric Evaluation ofWeld in Metallic Wires: A 3-D Simulation and Experimental Validation
No full textThis paper is focused on the real-time characterization of weld in high speed high-end drawn metallic wires using encircling coil eddy current sensor. Emphasis was laid on the evaluation of weld-length and its span of stability with a special reference to signal pattern recognition through the improvised non-linear regression tool. A 3-D CIVA simulation electromagnetic testing module was implemented to evaluate the theoretical expected response of the system. The qualitative and quantitative
analysis of welds was studied using signal processing of EC data. The percentage deviations in weld-span between simulated and experimental results were found to be around 1.6% and 12.5% at welding location of 1st and 8th pass respectively. This demonstrates the non- uniformity of the weld on relatively smaller diameter wire (8th pass) as compared to the larger diameter wire (1st pass). A good agreement was observed between the theoretical and experimental results. From the applications
perspective, these findings indicate the importance on achieving higher efficiency combined with reliable quality control. On-line implementation of the proposed method satisfies both the requirements; detection accuracy and detection speed
The use of release analysis to show the selectivity of reagents towards differently sized feeds of the same coal
No full textRelease analysis is used to characterize the cleaning ability of coal fines. It defines the limit of separation at any target level of ash. Since flotation depends upon many factors like feed size and its composition, surface properties, and type of reagents, it is important to characterize the optimum boundary of separation. Release analysis following the BS7503 procedure was used to characterize a − 0.5 mm composite feed and three sized feeds, i.e., −0.5 + 0.25, −0.25 + 0.1, and −0.1 mm using different reagent combinations. Coal response reflected by release curves and corresponding batch flotation results for various reagent combinations was found to be different for all three feeds. No single combination of collector and frother could deliver the maximum separation over the entire clean coal ash range for all three feeds. Significant yields ranging from 35% to 86% could be obtained at the 13% to 17% ash level for the medium volatile metallurgical coal investigated. Release curves and subsequent batch flotation results were found to be sensitive to feed size, feed size distribution, and reagent combination types with their corresponding dosage indicating that the clean coal ash requirement would dictate the application of reagents. The investigation results further show that release analysis results can be reproduced by batch flotation
Organization of Bio-Molecules in Bulk and Over the Nano-Substrate: Perspective to the Molecular Dynamics Simulations
No full textThe properties of bio-molecules are explicitly influenced by their organization in bulk and vicinity of substrate. Organization of bio-molecules can be of various kinds such as folded, unfolded, helix, swollen, globule, and so forth. These organizations of bio-molecule also depend on the local surrounding environmental conditions like temperature, solvency, adsorption, and encapsulation. Variation in environmental conditions helps to manipulate and control the organizations for the desired applications. Adsorption and encapsulation of bio-molecule over substrate have many applications in the area of drug delivery, design and development of bio-sensors, advance bio-separation process, etc. Molecular dynamics simulation is a very powerful tool to investigate the molecular structures, synthesis process and optimum properties, etc. A large number of efficient force field parameters and molecular dynamics simulators are available for large-scale simulation
Indian Coal Ash: A Potential Alternative Resource for Rare Earth Metals (REMs)
No full textHuge scarcity of rare earth metals (REMs) globally, lack of good natural resources, and generation of tremendous coal ash containing REMs of power plant attracted the researchers to work in this area. The analysis of geologically distributed heterogeneous coal samples at CSIR-NML, India reports the presence of 0.5–1.5 kg/Ton REMs in particular seam of coal at Indian eastern part. In this regard, systematic leaching studies were made to recover REMs from Indian coal ash using hydrometallurgical technique. Maximum dissolution of REMs from coal ash take place using HCl of concentration ranging between 2 and 6 M at elevated temperature. From the obtained leach liquor, more than 90% REMs were recovered using oxalate precipitation. The process developed has tremendous potential to be commercialized after feasibility studies