The graphite （Gr）/MoS2 reinforced Mg self-lubricating composites were prepared through powder metallurgy. The composites were characterized for microstructure, physical, mechanical and wear properties. Gr/MoS2 p...The graphite （Gr）/MoS2 reinforced Mg self-lubricating composites were prepared through powder metallurgy. The composites were characterized for microstructure, physical, mechanical and wear properties. Gr/MoS2 phase in the composites was identified by XRD analysis. Microstructural observation showed that the Gr/MoS2 particles were homogeneously dispersed within the magnesium matrix. Micro-hardness was measured using an applied load of 5 g with a dwell time of 15 s at room temperature. Hardness of all the composites was measured to be in the range of VHN 29？34. The mechanical properties were studied using micro-hardness, tensile and compression tests. A fractographic analysis was performed using scanning electron microscope. The highest values of hardness, compressive strength and tensile strength were attained using Mg-10MoS2 composite. A pin-on-disk tribometer was used to measure the friction coefficient and the wear loss of the sintered composites. In addition to that, the friction and wear mechanism of the composites were systematically studied by worn surface characterization and wear debris studies using SEM analysis. The reduced friction coefficient and wear loss were achieved in MoS2 rather than Gr.展开更多
Highly surface active super paramagnetic colloidal suspensions of nano crystalline ferrofluid have been synthesized through wet-chemical route. Entrapment of magnetic domains presented in the nano ferrofluid in a poly...Highly surface active super paramagnetic colloidal suspensions of nano crystalline ferrofluid have been synthesized through wet-chemical route. Entrapment of magnetic domains presented in the nano ferrofluid in a polymer matrix like poly vinyl alcohol film was accomplished by developing polymer composite film in between two magnetic poles by solvent casting method. Similarly poly vinyl alcohol-ferrofluid composite films were also developed in the absence of magnetic field. Atomic force microscopy image of nano-composite film makes it clear that the film developed in the absence of magnetic field possesses randomly oriented domains, whereas film developed with magnetic field shows well aligned flux lines. The characteristics and nature of forces acting between magnetic domains along the magnetic flux lines were explored from magnetic force microscopy imaging. The number of flux lines developed in the polymer matrix was observed to be directly proportional to applied external magnetic field. Approximate number of magnetic lines passing through unit area of composite film was evaluated from line profile data analysis of atomic force microscopy image. The particle sizes of the nanoparticles encapsulated in the polymer matrix were found to be in the range of 10- 20 nm. Scanning electron microscopy micrographs confirm aggregation of ferrofluid particles of ribbon like morphology along the magnetic flux lines. Magnetic properties of the entrapped nanoparticles in polymer matrix film were analyzed using vibrating sample magnetometer at room temperature. The super paramagnetic nature and other magnetic properties were evaluated from the hysteresis loop.展开更多
This article describes the growth of zinc sulfide（ZnS） nanorod on glass/aluminum foil by employing butterfly wings as biotemplate. Upon calcinating（at 400 °C）, the butterfly wings soaked in ZnS nanoparticle s...This article describes the growth of zinc sulfide（ZnS） nanorod on glass/aluminum foil by employing butterfly wings as biotemplate. Upon calcinating（at 400 °C）, the butterfly wings soaked in ZnS nanoparticle suspension, with uniform cage-like nanostructures in nanodimensions, were found on glass/aluminum surface. The transverse and longitudinal dimensions of the nanorods were evaluated from scanning electron microscopy micrographs as 132 and 159 nm,respectively. Purity of the ZnS nanorod found on the specimen was checked by recording XRD（28.877°, 48.038°, and57.174°） and Fourier transform infrared spectrometer spectra（663.7 and 551.68 cm^-1）. Luminescence natures of the nanorods were examined using photoluminescence spectral studies. The characteristic emission peak is shown in the visible region with strong intensity, while the excitation peak is shown at 267 nm. Electrochemical impedance spectroscopic analysis of ZnS nanorod exhibits double-layer capacitance value（Cdl= 6.7 nF）, and the Bode plot explains the stability of ZnS nanorod under the influence of electrical field.展开更多
Graphene oxide was synthesized from graphite flakes using modified Hummers’method.The interlayer spacings of graphite,graphite oxide and graphene oxide were measured using X-ray diffraction technique.The C/O atomic r...Graphene oxide was synthesized from graphite flakes using modified Hummers’method.The interlayer spacings of graphite,graphite oxide and graphene oxide were measured using X-ray diffraction technique.The C/O atomic ratios of graphite oxide and graphene oxide were calculated from XPS measurements.The transformation of graphite to graphite oxide and finally to graphene oxide was clearly observed from the micro-Raman spectroscopy data and was confirmed from the FESEM micrographs.UV-VIS-NIR spectrophotometer was used to study the absorbance of graphene oxide and reduced graphene oxide samples.Finally,the chemically reduced graphene oxide was heat-treated in air to obtain chemically modified graphene.展开更多
文摘The graphite （Gr）/MoS2 reinforced Mg self-lubricating composites were prepared through powder metallurgy. The composites were characterized for microstructure, physical, mechanical and wear properties. Gr/MoS2 phase in the composites was identified by XRD analysis. Microstructural observation showed that the Gr/MoS2 particles were homogeneously dispersed within the magnesium matrix. Micro-hardness was measured using an applied load of 5 g with a dwell time of 15 s at room temperature. Hardness of all the composites was measured to be in the range of VHN 29？34. The mechanical properties were studied using micro-hardness, tensile and compression tests. A fractographic analysis was performed using scanning electron microscope. The highest values of hardness, compressive strength and tensile strength were attained using Mg-10MoS2 composite. A pin-on-disk tribometer was used to measure the friction coefficient and the wear loss of the sintered composites. In addition to that, the friction and wear mechanism of the composites were systematically studied by worn surface characterization and wear debris studies using SEM analysis. The reduced friction coefficient and wear loss were achieved in MoS2 rather than Gr.
文摘Highly surface active super paramagnetic colloidal suspensions of nano crystalline ferrofluid have been synthesized through wet-chemical route. Entrapment of magnetic domains presented in the nano ferrofluid in a polymer matrix like poly vinyl alcohol film was accomplished by developing polymer composite film in between two magnetic poles by solvent casting method. Similarly poly vinyl alcohol-ferrofluid composite films were also developed in the absence of magnetic field. Atomic force microscopy image of nano-composite film makes it clear that the film developed in the absence of magnetic field possesses randomly oriented domains, whereas film developed with magnetic field shows well aligned flux lines. The characteristics and nature of forces acting between magnetic domains along the magnetic flux lines were explored from magnetic force microscopy imaging. The number of flux lines developed in the polymer matrix was observed to be directly proportional to applied external magnetic field. Approximate number of magnetic lines passing through unit area of composite film was evaluated from line profile data analysis of atomic force microscopy image. The particle sizes of the nanoparticles encapsulated in the polymer matrix were found to be in the range of 10- 20 nm. Scanning electron microscopy micrographs confirm aggregation of ferrofluid particles of ribbon like morphology along the magnetic flux lines. Magnetic properties of the entrapped nanoparticles in polymer matrix film were analyzed using vibrating sample magnetometer at room temperature. The super paramagnetic nature and other magnetic properties were evaluated from the hysteresis loop.
文摘This article describes the growth of zinc sulfide（ZnS） nanorod on glass/aluminum foil by employing butterfly wings as biotemplate. Upon calcinating（at 400 °C）, the butterfly wings soaked in ZnS nanoparticle suspension, with uniform cage-like nanostructures in nanodimensions, were found on glass/aluminum surface. The transverse and longitudinal dimensions of the nanorods were evaluated from scanning electron microscopy micrographs as 132 and 159 nm,respectively. Purity of the ZnS nanorod found on the specimen was checked by recording XRD（28.877°, 48.038°, and57.174°） and Fourier transform infrared spectrometer spectra（663.7 and 551.68 cm^-1）. Luminescence natures of the nanorods were examined using photoluminescence spectral studies. The characteristic emission peak is shown in the visible region with strong intensity, while the excitation peak is shown at 267 nm. Electrochemical impedance spectroscopic analysis of ZnS nanorod exhibits double-layer capacitance value（Cdl= 6.7 nF）, and the Bode plot explains the stability of ZnS nanorod under the influence of electrical field.
文摘Graphene oxide was synthesized from graphite flakes using modified Hummers’method.The interlayer spacings of graphite,graphite oxide and graphene oxide were measured using X-ray diffraction technique.The C/O atomic ratios of graphite oxide and graphene oxide were calculated from XPS measurements.The transformation of graphite to graphite oxide and finally to graphene oxide was clearly observed from the micro-Raman spectroscopy data and was confirmed from the FESEM micrographs.UV-VIS-NIR spectrophotometer was used to study the absorbance of graphene oxide and reduced graphene oxide samples.Finally,the chemically reduced graphene oxide was heat-treated in air to obtain chemically modified graphene.
