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Shock wave induced exfoliation of molybdenum disulfide (MoS2) in various solvents: All-atom molecular dynamics simulation
No full textMolybdenum disulfide (MoS2) depicts a 2-dimensional layered structure. It is known as multi-utility and multi-functional material based on its capability to exhibit a change in properties due to a reduction of size from bulk to the nanoscale. Mostly, 2-D MoS2 has been synthesized by the liquid-phase exfoliation of bulk MoS2. However, the actual effect of the various solvent and external forces on the mechanism of the exfoliation process of MoS2 needs more investigation. In the present investigation, we have carried out extensive large scale all-atom molecular dynamics simulations to demonstrate the mechanism of solvent-assisted exfoliation of bulk MoS2 by applying a single pulse of shock wave involving commonly used solvents like Methanol, isopropanol (IPA), N-methyl-2-pyrrolidone (NMP), Di-methyl-formamide (DMF), Di-methyl sulfoxide (DMSO), etc. We have used OPLSAA and SPCE force fields for the implementation of various kinds of inter-atomic interactions between atoms of MoS2 and solvents. We have shown a very realistic exfoliation process of a stack of multi-layer MoS2 sheets in the various solvent by both visual snapshots and quantitative analysis. It has been revealed that the type of solvent and velocity of shock wave pulse significantly influence the exfoliation process of MoS2. Solvent accessible surface area (S), volume (V), dimensionless aspect ratio () and various components of energy have been estimated for the quantitative characterization of the exfoliation process of MoS2. Present results will provide extensive scientific information related to the synthesis and development of 2D materials at both laboratory and industrial scale
Recovery of Manganese and Cobalt from Discarded Batteries of Toys
No full textCompared to other electronic goods, life span of children’s toys is very less, which resulted in the generation of huge amount of batteries and environmental pollution. Initially, the batteries are discharged, dismantled, crushed, and physically beneficiated to get black powder, metallic fraction, and plastics. Further, the black powder of batteries was processed for systematic leaching studies and
found that 95.6% Mn and 86.05% Co were leached in 2 mol/L H2SO4 at 30 °C in 120 min using 10% H2O2 (v/v) as an oxidant, maintaining the pulp density 75 g/L. From the leach liquor, at pH 5–8 and above 12, the oxides of Co and Mn were
obtained, respectively. The developed process has potential to be transferred in an industry after scale-up studies
Utilization of Roast-Reduced Ilmenite Leach Liquor for Ferrous Chloride Production by Hydrothermal Process
No full textIlmenite is the most abundant mineral for the extraction of titanium. It contains more than 50% TiO(2)along with iron, silica and alumina. The spinel structure of ilmenite (FeO center dot TiO2) is such that iron is bound in the lattice of TiO(2)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 is 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 to be 0.31. This leach liquor contains hydrochloric acid and iron as ferrous chloride. These acid and solid masses were separated by hydrothermal process in the present investigation. The residue containing ferrous chloride was characterized with the help of XRD and EPMA. During the experiment it was found that complete separation of HCl and FeCl(2)is feasible. The final pH of separated HCl is found to be 1.66 and it is suitable for reuse in the leaching of reduced ilmenite and the process makes a loop. The purity of ferrous chloride is in line with commercial grade which is a saleable product
Amorphous carbon dot and chitosan based composites as fluorescent inks and luminescent films
No full textA composite of self-passivated amorphous carbon dots (CDs) and chitosan has been developed and utilized to form fluorescent inks and luminescent films. The ink is invisible under visible light but glows brightly under external excitation. Cross-linking between the numerous surface groups present in the highly disordered CDs and chitosan, endow the inks and films with enhanced optical and mechanical properties. The amorphous CD based ink is capable of writing on nearly all types of surfaces and exhibits excellent anti-clogging and anti-smearing properties. The luminescent films on the other hand are characterized by good mechanical strength (sigma(UTS) approximate to 61.3 MPa) along with high luminescence efficiency. The luminescence yield, ultimate tensile stress, hydrophobicity and glass transition temperature of the films were found to scale similarly with the concentration of CDs in chitosan. All the parameters initially improved with increasing CD concentration but then deteriorated beyond some optimal CD loading due to agglomeration effect. We demonstrate that the amorphous carbon dot-based inks and films outperform all other carbon-based fluorescent inks and films prepared from the more expensive crystalline structures
The Separation of Aluminum and Stainless‐Steel Scraps Using Vibrating Mixed‐Size Ball Bed
No full textDry gravity separation using a vibrating zirconia ball bed is proposed in this study to
separate aluminum (Al) and stainless steel (STS) scraps obtained from spent hard disk drive
recycling. The effects of zirconia ball sizes and vibrating power (vibration amplitude) on the
separation efficiency of Al and STS scraps were investigated. The zirconia balls moved down at the
center of the vessel and rose with the wall during the vibration test. Although more STS scraps sunk
than Al scraps did, the separation efficiency was not maintained because Al scraps also sunk along
with balls’ movement. The separation efficiency increased to 86.6% using 1‐mm zirconia balls with
a 2.5‐mm vibration amplitude at 4 min, but it decreased rapidly by ball moving. Therefore, when a
ball bed of mixed sizes (2:1 ratio of 1 and 3 mm) was used and arranged, whereby the 3‐mm zirconia
balls were above the 1‐mm ball bed, the separation efficiency increased to 100% for more than 2 min.
This dramatic improvement was because the 3‐mm ball bed acted as a barrier to prevent sunken
STS scraps from rising, and Al scrap cannot sink through the 3‐mm ball bed. These results indicate
that the separation of Al and STS scraps could be achieved successfully using the dry gravity
separation method.
Performance evaluation of surface modified nano Al2O3 (p) reinforced AZ91E composites under impact and fatigue loading conditions
No full textThis paper confers to compare the behavior of AZ91E, AZ91E with 2 wt. % plain and surface modified alumina reinforced composites under different loading conditions. The composites were prepared and specimens were cut in accordance with standard procedures to conduct impact and fatigue tests. Surface modified alumina reinforced AZ91E magnesium based composites resulted in improved impact and fatigue strength because of good interactions between the matrix and reinforcement. The results are discussed
A study on the impact and fatigue failure of AZ91E–Ni coated alumina composites
No full textFailure analysis is a key concern in the development of composites. It not only helps to understand
the material performance under severe loading conditions but also to decide the suitability of the
material in particular applications. In this context, this paper highlights the behaviour of AZ91E with
2 wt-% nickel-coated alumina reinforced composites under different loading conditions.
Composites were fabricated by semi-solid stir casting route while impact, and fatigue tests are
conducted according to standard procedures. The properties of the prepared composite are
discussed and compared with the monolithic alloy AZ91E. Ni coated alumina reinforced AZ91E
magnesium-based composites yielded improved impact and fatigue strength because of good
bonding between the matrix and reinforcement achieved through a metallic coating on the
ceramic reinforcement. Further fractographical analysis is presented to understand the
mechanism of failure.
L’analyse de rupture est une préoccupation clé dans le développement des composites. Elle permet
non seulement de comprendre le rendement du matériau dans des conditions de charge sévères
mais également de décider de l’aptitude du matériau pour des applications particulières. Dans ce
contexte, cet article met en évidence le comportement de composites d’AZ91E renforcés d’alumine
enrobée de 2% en poids de nickel dans différentes conditions de charge. On a fabriqué les
composites par voie de moulage semi solide avec agitation alors qu’on a effectué les essais
d’impact et de fatigue d’après les normes de procédures. On discute des propriétés du
composite préparé et on les compare à l’alliage monolithique AZ91E. Les composites à base de
magnésium AZ91E renforcés d’alumine revêtue de nickel produisaient une amélioration de la
résistance à l’impact et à la fatigue grâce à une bonne liaison entre la matrice et le
renforcement, obtenue par l’intermédiaire d’un revêtement métallique sur le renforcement en
céramique. On présente une analyse fractographique plus approfondie pour comprendre le
mécanisme de rupture
Impact of Pre-formed Martensite on the Electromagnetic Properties and Martensitic Transformation Kinetics of Uniaxially Tensile Loaded 304 Stainless Steel
No full textThe investigation addresses the influence of tensile deformation on the magnetic properties of 304SS samples in their as-received state as well as those with martensite content of 12 and 17%. Non-destructive electromagnetic techniques like magnetic Barkhausen emission (MBE) and magnetic hysteresis loop have been used to measure variation in MBE voltage and coercivity, respectively, during plastic deformation through tensile loading. As both the techniques use surface probe, the present investigation will be useful for in situ evaluation of structural components. With progressive plastic deformation, those measurements revealed different stages of deformation indicated by change in MBE signal and magnetic coercivity. The stages of magnetoelastic response, strain-induced martensitic transformation, dislocation pile-ups and formation of voids reflected different patterns of magnetic Barkhausen emission and magnetic coercivity variation with progressive straining of austenitic stainless steel samples. The changes in true strain with variation in martensite content along gauge length of fractured samples have been analyzed with respect to martensite transformation kinetics. Mathematical fitting methodology has been adopted to distinguish as-received and pre-strained martensitic transformation characteristics. In situ magnetic NDE and associated martensitic transformation parameters may be useful for structural health monitoring of in-service components
Multifunctional properties of electrodeposited nickel composite coating containing nanosized monoclinic zirconia particles
No full textNickel-based composite coatings containing ceramic particles as the distributed phase have been widely used in aerospace and automotive industries. In the present work, a Ni-composite coating containing nanosized monoclinic zirconia (ZrO2) powder is prepared by solution combustion (SC) method. The SC method is modified to get phase pure white zirconia powder by using the mixture of fuels approach. Since the synthesized powder contained agglomerated particles, the powder is ball milled and dispersed in a nickel sulphamate bath. The Ni and Ni-ZrO2 coatings are electrodeposited at 0.75 A/dm2 for 6 h. The Ni-ZrO2composite coating exhibits a microhardness of 750 KHN(50 gf) as against 270 KHN(50 gF) observed for plain Ni coating. The Ni-ZrO2 coating exhibits improved corrosion resistance and wear resistance compared to plain nickel coating as confirmed by potentiodynamic polarization and continuous salt spray tests. The as-deposited hydrophobic Ni-ZrO2coating transforms to superhydrophobic upon depositing a thin layer of fluoroalkyl silane on the coating. Thus, the synthesized zirconia particles when incorporated in the Ni matrix impart multifunctional properties to the electrodeposited Ni coating
Technology glimpse of bioceramic implants developed by CSIR-CGCRI, Kolkata
No full textFor the last two decades, Bioceramics Group of CSIR-Central Glass and Ceramic Research Institute (CSIRCGCRI), Kolkata has been engaged in the development of new generation of ceramic materials for different biomedical applications. The group has developed hip joint prosthesis with ceramic heads, hydroxyapatitebased bone fillers and ocular implants which after successful animal trials have been assessed through clinical trials at different hospitals (Calcutta Medical Research Institute, Kolkata; Advanced Medical Research Institute, Kolkata; All India Institute of Medical Sciences, New Delhi and Moulana Azad Medical College, New Delhi for hip implants and bone fillers and Eye Care and Research Centre, Kolkata; All India Institute of Medical Sciences, New Delhi, Sir Gangaram Hospital, New Delhi, Moulana Azad Medical College, New Delhi, Shankara Nethralaya, Chennai, Sri Sankardeva Nethralaya, Guwahati, Sarojini Devi Eye Hospital, Hyderabad and Disha Eye Hospital, Barackpore) in the country. These technologies have been commercialized and available in Indian market through M/s IFGL Bio-ceramics Ltd., Kolkata since January, 2005. Thereafter, few of the technologies have been transferred to other Indian companies who are in the process of obtaining manufacturing license from DCGI before commercialization. The Institute has also developed coatings on metallic implants by plasma spraying hydroxyapatite/other calcium phosphates for cement-less fixation in the human subjects. These clinical trails were primarily carried out at Sancheti Institute of Orthopedic and Rehabilitation, Pune under the leaderships of Padmavibhushan Dr. K.H. Sancheti. Further, the Institute has also actively participated in few CSIR network programmes to develop coated implants using diamond-like nano-composite (DLN) and standardize laser engineered net shaping (LENS) process for development of patient specific prosthesis of irregular shapes