Sharif Digital Repository

In the present study, the surface chemical and depth profile composition of the electrodeposited Ni-Fe base alloy layers on the Cu substrates were investigated with compositions of the Ni80-Fe20 (binary) and Ni77-Fe20.7-Cr1.7-Mo0.6 (quaternary) deposits. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) results showed the surface accumulation of copper on the surface layers of binary alloy films in the form of Cu 2O. In the quaternary films, addition of Cr and Mo reduced the amount of the Cu accumulation at the surface, while Cu accumulation was enhanced under air-exposed condition for both alloy films. Depth profiles using the secondary ion mass spectroscopy... 

Herein, NiO and Co2 O3, NiCo2 O4, and NiCo2 O4 /multi-walled carbon nanotubes nanocomposite were synthesized by the hydrothermal method and characterized by scanning electron micros-copy, energy dispersive spectroscopy, and X-ray diffraction. The photocatalytic activity of the synthesized materials was evaluated by Reactive Red 120 dye degradation. The photocatalytic activity of NiO and Co3 O4 was enhanced not only by the formation of NiCo2 O4, but also by its interaction with the functionalized multiwall carbon nanotubes support. The response surface methodology (RSM) was used to obtain the optimum parameters, including catalyst dosage, initial dye concen-tration, and pH on the dye... 

Ni-Fe and the Ni-Fe-Cr-Mo alloy films were electrodeposited from a chloride solution containing complexing compounds on ITO/glass substrates. AFM studies revealed a spherical structure for the alloy films with roughnesses from 10 up to 50 nm. The Ni-Fe-Cr-Mo alloy films were found to have a fine-grain structure. The quaternary alloy compounds containing up to 4% Cr and 2% Mo showed higher resistivity and little decrease in magnetoresistance (MR) relative to the Ni80Fe20 alloy compound. The MR of the quaternary alloy compounds was decreased for higher Cr and Mo contents. Moreover, the anisotropy (AMR) was also decreased by the addition of Cr and Mo to Permalloy films. Auger studies indicated... 

An enhancement in heat transfer due to nanofluids is essentially required in various thermal systems. Hybrid nanofluids possess high thermal conductivity and, have ability to embellish and enhance the thermal strength of common fluids. Our concern in this paper is to examine the innovative attributes of hybrid nanofluids like Manganese zinc ferrite (MnZnFe2O4) and Nickel zinc ferrite (NiZnFe2O4) in the bio-convective flow of motile gyrotactic microorganisms subject to Darcy Forchheimer medium. The effect of activation energy has also been taken into account. Mathematical treatment is carried out via MATLAB software. The use of MnZnFe2O4 - NiZnFe2O4/H2O exhibits improved thermal... 

A highly efficient polybutylene terephthalate (PBT)-based nanocomposite containing nickel oxide nanoparticles was synthesized by electrospinning technique and used as a fiber coating for solid phase microextraction. The influential morphological parameters and capability of the prepared nanocomposite including the NiO content, the coating time, the PBT concentration and applied voltage were considered for optimization. The applicability of the synthesized fiber coating was examined by headspace solid phase micro extraction and gas chromatography mass spectrometry detection of some volatile organic compounds in aqueous samples. Among the synthesized nanocomposites and pristine PBT nanofibers,... 

In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni-1%Co coatings had a better corrosion resistance 0.30, 0.92 and 3.75 mpy for atmospheric, salt spray and polarization tests, respectively. These are 0.41, 1.20 and 5.40 mpy for pure nickel coatings that indicate the least corrosion resistance. Surface analysis revealed the presence of oxides, sulphides and chlorides in corrosion products  

Superalloys have a poor machinability and are often drilled using Electro Discharge Machining (EDM) methods. However EDM is a time-consuming process and has low surface integrity. Ultrasonic Assisted Drilling (UAD) technology is a modern method of drilling such materials. Although this method has very high capabilities, it has not been introduced widely to industry. In this study a special horn is designed and used to apply both rotation and vibration to drill bits. It can transfer power with high efficiency and has the capability to change tools easily. The setup is used to conduct deep drilling tests on Inconel 738LC with depth-to-diameter ratio of 10. The effect of ultrasonic vibration... 

This paper addresses solidification and solid state precipitation phenomena during transient liquid phase (TLP) bonding of wrought IN718 nickel base superalloy using Ni-4.5Si-3.2B (wt.%) ternary filler alloy. The solidification sequence of the residual liquid in the joint centerline was found to be (1) formation of proeutectic γ, followed by (2) γ/Ni3B eutectic reaction, followed by (3) ternary eutectic of γ/Ni 3B/Ni6Si2B. Extensive fine Ni3Si formed within the eutectic-γ via solid state precipitation during cooling. Extensive Cr-Mo-Nb rich boride precipitates were formed in the substrate region due to boron diffusion into the base metal during bonding process. The implications of the phase... 

The geometry structures of hexa-coordinated [NiLX]X complexes (X = Cl -, Br-, I-) {L = 8,9,18,19-tetrahydro-7H,17H- dibenzo[f,o] [1,5,9,13]dioxadiaza cyclohexadecine-8,18-diol} are optimized by density functional theory (DFT) using B3LYP/LANL2DZ. The calculated geometric parameters are in good agreement with the corresponding experimental values. Calculation results about these complexes show that dipole moment decreases, and the energy levels of HOMOs descend from iodo-complex to chloro-complex. The energy levels of HOMOs descend gently from iodo-complex to chloro-complex, while the energy levels of LUMOs in the present complexes are almost similar; therefore the energy gapes between HOMOs... 

In this study, a particular nickel-based superalloy has been studied by transmission electron microscopy and the results are discussed in terms of phase transformations that may have taken place. The alloy has been found to consist of three major phases; a FCC γ phase containing a random distribution of nearly spherical γ′ - Ni3Al(Ti) - precipitates and elongated thin Ni3Ti(Ta) platelets with a hexagonal structure. The orientation relationships between the different phases have been determined; loss of coherency and possible occurrence of misfit-relieving interfacial dislocations are discussed and compared with experimental observations, and possible mechanisms of phase transformations are... 

A three-dimensional (3D) graphene/Nickel oxide (ERGO/NiO) composite electrode have been fabricated directly on a Nickel foam substrate via a one-step electrochemical co-deposition in an aqueous solution containing Nickel nitrate and GO. By using this simple and one-step electrochemical deposition, it is possible to produce binder-free composite electrodes with improved electrochemical properties using a low-cost, facile and scalable technique. It is observed from FE-SEM images that graphene oxide sheets affect the electrodeposition of nickel oxide. The optimized ErGO/NiO electrode developed in this work exhibits high charge storage capacity with a specific capacitance of 1715.5 F g−1 at... 

Nickel nanostructure thin films were electrodeposited on copper plates to investigate the fractal study. Scharifker's equations were derived for instantaneous and progressive nucleation and 3D growth of hemispherical centres under diffusion-controlled condition to calculate in situ change of fractal dimension of surface. It was assumed that the layer could be formed completely when fractal dimension of surface inclined to 2. Moreover, the fractal analysis of atomic force microscopy (AFM) images has confirmed the presumed model. Also, the power values of power spectral density (PSD) of the AFM images were determined using fast Fourier transform (FFT) algorithms. The PSD plots are approximated... 

Two new heteronuclear Nickel(II)/Sodium(I) complexes of a side-off compartmental Schiff base ligand were synthesized and characterized by spectroscopic methods. Crystal structures of both of the complexes were also obtained. The Schiff base ligand was synthesized from the condensation of meso-1,2-diphenyl-1,2-ethylenediamine with 2-hydroxy-3-methoxybenzaldehyde. In both of the complexes the Ni(II) ion is coordinated to the inner N2O2 coordination sphere with square-planar geometry and the Na(I) ion is coordinated to the outer O2O2′ coordination sphere. In Complex (1) with general formula [Ni(L)Na(CH3OH)(ClO4)] the sodium ion is seven coordinated while in (2) with general formula... 

A new magnetic heterogeneous catalyst was synthesized by immobilization of nickel ions onto a cross-linked polymeric nanocomposite composed of cyanuric chloride, ethylenediamine and functionalized magnetic nanoparticles. The resulting nitrogen rich support was capable of adsorbing large amounts of nickel ions (1.20 mmol g−1). The synthesized catalyst was characterized using AAS, TEM, FT-IR, EDX, TGA, SEM, BET and XRD techniques. The performance of the prepared catalyst was investigated in the C-N coupling of arylamines with aryl boronic acids. The reaction was carried out under a mild condition and good to moderate to good yields of products was obtained using only 5.0 mol% of the catalyst.... 

This paper describes the effects of using direct and pulse current on composition and corrosion resistance of Fe-Ni-Cr alloy coatings. In both direct and pulse current electrodeposition, increasing the current density has a decreasing effect on Fe and Ni and an increasing influence on Cr. In pulse current electrodeposition, duty cycle has a greater effect than frequency on composition of the alloy coating, particularly in the range of 10-50%. In this range, by increasing the duty cycle, Ni decreases, Fe sharply increase and Cr shows an increasing trend. Following a study of the microhardness of coatings, it is determined that the microhardness increases about 1.5 times by pulse current... 

The effects of particle size and alloying elements on the size and morphology of secondary/intermetallic phases in gas atomized Al-20Si-5Fe-2X (X = Cu, Ni, Cr) powders were studied. The microstructure composed of particle-like primary Si with average diameter of 0.5-2.7 μm, δ-Al4FeSi2 intermetallic compound containing small amount of dissolved alloying elements with the size of 1.4-7.7 μm, and fine Al-Si eutectic matrix with 0.25-0.4 μm spacing. As the powder particle size decreases, the primary silicon becomes finer while its morphology is not affected. For instance, 58-75% reduction in the size of primary silicon was observed when decreasing the average particle size from 89 to 18 μm. A... 

In this research, a series of NiO–MgO–SiO2 catalyst samples with various nickel contents (5, 10, 15 and 20 wt %) were prepared by a co-precipitation method followed by a hydrothermal treatment and employed in propane steam reforming. The analyses revealed that the enhancement of the nickel content up to 15 wt % improved the propane conversion to 98.6% at 550 °C. Nonetheless, further increase in the nickel loading reduced the catalyst activity due to the formation of larger and more poorly dispersed active sites. Besides, 15 wt % nickel loading led to the high resistance against coke deposition with no detectable carbon on the catalyst surface. In addition, it was revealed that, the decrease...