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Weakly coupled metal-semiconductor plasmonic nanoparticles in solution
No full textThe optical properties of binary metal-semiconductor (gold-copper sulphide, both of which are plasmonic in nature) nanoparticle system has been investigated in solution, demonstrating a clear plasmonic coupling between them, due to proximity effect. Monodisperse nanoparticles of gold and copper sulphide were first synthesized using reported methods and then characterized using advanced instrumental techniques. Upon gradual addition of copper sulphide nanoparticle dispersion to that of gold nanoparticles, the intensity of the characteristic localized surface plasmon resonance (LSPR) peak of gold nanoparticles gets reduced, while that of the copper sulphide increases and an ‘isosbestic point’ could be observed. However, the reduction and the increase in the intensities do not follow the trends as expected from simple dilution/increase in the concentrations indicating a plasmonic coupling between them. The same coupling in the mixed state could be seen with respect to the shift in binding energies of the core-level orbitals of the both the materials, from the XPS spectra. Thus, the present study exemplifies a facile solution method to tune the LSPR bands in plasmonic nanomaterials for any potential device application
Ratcheting Fatigue Behaviour of Zircaloy-2 at 300 degrees C
No full textIn laboratory, materials designed for engineering applications, specifically for fatigue, are generally tested under symmetrical cyclic loading (stress ratio, R = -1), but many structural components exhibit less fatigue life than predicted from symmetric loading due to asymmetric cyclic loading during service. This study deals with fatigue behaviour of Zircaloy-2 and presents the effect of mean stress (sigma(m)), stress amplitude (sigma(a)), stress rate ((sigma) over dot) on fatigue life, deformation and fracture behaviour at 300 degrees C under asymmetric cyclic loading. A series of fatigue tests are performed at 300 degrees C under asymmetric stress-controlled loading with different combinations of sigma(m) (60-80 MPa), sigma(a) (115-135 MPa) and (sigma) over dot (30-750 MPa/s). Deformation behaviour and microstructural changes under the influence of above parameters (sigma(m), sigma(a) and (sigma) over dot) are examined by transmission electron microscope. It is observed that plastic strain increases with rise in sigma(m) as well as sigma(a) and cyclic life is reduced; on the other hand, with increase in (sigma) over dot accumulation of plastic strain decreases and fatigue life is enhanced. The results are correlated with microstructural changes and fracture behaviour of the material under different test conditions
Role of particle fineness on engineering properties and microstructure of fly ash derived geopolymer
No full textFly ash is ball milled for 30 and 90 min duration to obtain two finer fractions. The degree of size reduction
is very significant at the early stage of milling, then because of agglomeration effect size reduction becomes sluggish. The effect of particle size on physical, mechanical and microstructural properties of resultant geopolymer is elucidated. The physical properties and mechanical strength improvement with milling time is attributed with formation of higher amount of alkaline alumino-silicate (N-A-S-H) hydrated gel. The weight loss profile in Thermo-gravimetric analysis (TGA) indicates more hydrated gel formation and lower carbonation with finer fraction. Different techniques such as Fourier transforms infrared spectroscopy (FTIR), X-ray diffractometer (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) have been used for microstructural evaluation of geopolymers.
In FTIR, the asymmetric stretching of Si–O–T (T is Si/Al) has been shifted towards lower frequency due to
structural alteration of Al–Si network. The crystalline peak intensity has been decreased because of formation of amorphous gel after geopolymerization, detected by XRD. Under SEM and TEM, finer fraction is characterized with formation of more reaction product. The counts of un-reacted and non-bridge particles are decreased with size reduction
Global Outlook on the Availability of Critical Metals and Recycling Prospects from Rechargeable Batteries
No full textThis chapter covers the availability of all critical metals in batteries and their prospects for recycling
Performance evaluation of a laboratory floatex density separator and its comparison with a spiral concentrator
No full textTwo different samples were collected from the Beneficiation Plant (BP) for detailed studies. Sample I and Sample II are the feeds to the spiral concentrator from an existing beneficiation circuit of BP at JSW steel with two different size fractions of −1 mm + 150 µm assaying 53.26% Fe, 13.94% SiO2, 6.88% Al2O3 and −150 µm assaying 51.7% Fe, 17.4% SiO2, 4.3% Al2O3, respectively. The samples consist of hematite as the major iron-bearing mineral and goethite as the minor iron-bearing mineral. In both sample it was found that interlocked phases of hematite with gangue minerals like koalinite, quartz etc in varying proportion. Laboratory trials have been carried out using FDS by varying the teeter water flow rate and bed height set point at constant feed flow rate. For the spiral concentrator the feed rate, slurry density and splitter position were varied. Test results indicated that FDS was highly selective in rejecting siliceous and aluminous gangue from iron ore compared to the spiral concentrator
Utilization of roast reduced ilmenite leach liquor for ferrous chloride production by hydrothermal process
Get PDFIlmenite is the most abundant mineral for the extraction of titanium. It contains more than 50% TiO2 along with iron, silica and alumina. The spinel structure of ilmenite (FeO.TiO2) is so that iron is bounded in the lattice of TiO2 matrix. To remove iron from the ilmenite is a major task for process metallurgists. Various processes have been applied to remove this iron. One of them is reduction and leaching. The carbon containing pellets and environment of jhama coal reduces the iron oxide to metallic state. This metallic iron in then leached in dilute hydrochloric acid (20 vol%) and a greenish color leach liquor is obtained. The pH of the leach liquor solution is found 0.31. This leach liquor contains hydrochloric acid and iron as ferrous chloride. These acid and solid mass was separated by hydrothermal process in the present investigation. The residue containing ferrous chloride was characterized with the help of XRD and EPMA. During experiment it was found that complete separation of HCl and FeCl2 has done. The final pH of separated HCl is found 1.66 and it is suitable for reuse in the leaching of reduced ilmenite and process make a loop. The purity of ferrous chloride is in line with commercial grade which is a sellable product
Perspective of availability and sustainable recycling prospects of metals in rechargeable batteries – A resource overview
No full textThe growing need for strategic and rare earth elements (REE) led to an enormous interest in the development of new technologies for the recycling and recovery of these metals from secondary resources especially batteries. The primary reserves, production scenario and possible secondary resources of cobalt, lead, lithium, manganese, nickel, REE, and zinc, with respect of metal content, quantity, the source of generation is discussed. The purpose of this review is to depict the status of the recycling technologies for the extraction of metals inherent in primary and secondary batteries from secondary resources like process wastes, catalysts, effluents, metal and alloy scrap, e-wastes, mine tailings, and metallurgical slags and spent batteries, depicting a summary of those under-utilized wastes. Also, the problems and the prospect of the studies of their recycling technologies especially focused on the hydrometallurgical and pyrometallurgical processes have been put forward. The future avenues in spent battery recycling are also discussed with respect to the directions of research needed for their sustainable utilization and environmental management
Neural Network Modelling to Characterize Steel Continuous Casting Process Parameters and Prediction of Casting Defects
No full textThe current work outlines application of a data-driven multilayer perceptron-based artificial neural network (ANN) model to characterize the influence of melt compositions, tundish temperature, tundish superheat, casting speed and mould oscillation frequency on the important processing parameters such as mould powder consumption rate, oscillation mark depth and metallurgical length during continuous casting process. A two-layer feedforward back-propagation neural network model has been developed for predicting the probability of occurrence of defect in the cast product. The network training architecture has been optimized using a gradient-based algorithm, namely the back-propagation algorithm. The neural network predictions are found to be in good agreement with regard to oscillation mark depth, mould powder consumption rate, metallurgical length and probability of occurrence of defect using data obtained from an operating Indian steel plant (Rashtriya Ispat Nigam Limited, Visakhapatnam). The ANN model prediction has been validated successfully with multiple linear regression analysis carried out on each data set
Crystal growth, structural, optical, magnetic and thermal properties of pure and thiourea doped L-alanine single crystals for nonlinear optical applications
No full textAn organic L-Alanine (LA) and Thiourea doped L-Alanine (TLA) are nonlinear optical single crystals grown in low temperature by solvent evaporation technique at room temperature. The crystallite size of LA and TLA were estimated with the help of powder X-ray diffraction studies with 52.42 nm and 57.34 nm. It has been confirmed by the lattice parameters that grown LA and TLA belong to the system of orthorhombic. Again, the cut off wavelength is doped materials is 240 nm for pure and 302. It is clearly evident from PL Studies that major and sharp emission peak was obtained at 418.9 nm. The third order nonlinear optical susceptibilities of LA and TLA are 0.168 x 10−4 and 2.41 x 10−4 respectively. The sharp endothermic peaks at 284°C and 312° C for LA and TLA, indicates the melting point the crystals. Modes of vibrations and the presence of the functional groups were analyzed by FTIR studies. The estimated coercivity is 6542.9 for LA and 6623.7 for TLA respectively. TLA crystal is the most suitable material for fabrication of nonlinear optical devices
Recovery and Recycling of Cerium from Primary and Secondary Resources- a Critical Review
No full textVarious processes for the recovery of cerium from metallurgical, non-metallurgical and secondary sources are reviewed. Cerium is present as a major constituent of primary resources like monazite, bastnäsite, etc. Various secondary resources of cerium include phosphogypsum, red mud, blast furnace slag, NiMH batteries, FCC catalyst, glass films, CFLs, catalytic converters, etc. This review encompasses the research carried out for the extraction of cerium by pyro-hydrometallurgical methods followed by separation and purification with flowsheets. Also are enlisted in various processes like solvent extraction, ion exchange, membrane adsorption, ionic liquids, carbon-based nanomaterials, used for purification of cerium from the solution. Besides, the alternate methods to prepare cerium salts like fused salt electrolysis and metallothermic reduction are described