Papers by Keyword: Nickel

Abstract: This research investigates the nickel content added by 1.1wt%, 2.2wt%, 3.7wt% and 4.5wt% on the microstructure and mechanical properties in the nodular cast iron. The results demonstrate that the microstructure of nickel addition consists of nodule graphite, ferrite and pearlite phase while nickel was added to 4.5 wt% the microstructure becomes ferrite transform to fully pearlite phase. In addition the ductile iron has the highest nodularity (0.79%), followed by 1.1%Ni (0.75%), 2.2%Ni (0.71%), 3.7%Ni (0.69%) and 4.5%Ni (0.58%). The hardness and tensile strength increase when increasing the nickel content. Elongation is enhanced with nickel increasing and reaches a maximum of 12% at 1.1 wt% Ni, then decreases with the further increase of nickel.

Abstract: A novel redox couple of metallic nickel (Ni) catalyst can become a great candidate of non-enzymatic detection. By taking advantage of fast electron transfer, Ni redox couples can be tailored as pseudo-enzyme in urea measurement. In this study, Ni catalyst on nitrogen doped carbon (Ni-NC) was synthesized and characterized morphological, elemental, and electrocatalytic properties in comparison to different configuration of pure nickel (Ni), Ni with carbon (Ni-C), and bare carbon electrode, assessed by cyclic voltammetry and differential pulse voltammetry. By examining various Ni redox couples in rapid electron transfer process, the prominent anodic and cathodic peaks of Ni²⁺/Ni³⁺ were applicable to detect urea in the detection range of 1-20 mM, with an excellent sensitivity and relative standard deviation of 1.634 μA.mM^-1 (R² of 0.989) and 4.89%, respectively. Therefore, Ni-NC can find practical applications for material sensing device toward non-enzymatic urea measurement.

Abstract: The structure and misorientations of grain boundaries of ultrafine-grained nickel subjected to rolling and forging at liquid nitrogen temperature are studied. It is shown that as a result of rolling in UFG nickel obtained by the ECAP the forming of a band fragmented structure with the formation of special twin boundaries Σ3 is observed. An increase in the strain rate (forging) leads to the appearance of localized deformation bands in which the formation of new small grains is observed through dynamic recrystallization. The development of recrystallization results in increase up to 7% in UFG nickel the fraction of special twin boundaries Σ3 which are similar in nature to annealing twins.

Abstract: INCONEL 718 superalloy (IN 718) is frequently used in highly aggressive environments, such as aerospace and gas turbine engines, where excellent mechanical properties, creep-, fatigue- and oxidation-resistance performance at high and cryogenic temperatures are required. Recent studies have successfully cold sprayed IN 718, showing great potential mainly in maintenance and repairing fields. However, due to the low plastic deformation, the manufacture of IN 718 cold sprayed coatings often requires the use of expensive propulsive gases or high working parameters to enhance deposition efficiency, with a significant increase in production costs. This paper investigates for the first time the addition of Ni to IN 718 powders in order to increase plastic deformation and interparticle bonding strength. Four composite coatings were deposited via a high-pressure cold spray process using nitrogen as propulsive gas, considering different IN 718 mass fractions in the feedstock: C1 (0 wt%), C2 (25 wt%), C3 (50 wt%), C4 (75 wt%). The coatings are examined in terms of microstructural characteristics and tribological performance. The addition of IN 718 particles significantly improves the mechanical properties of the coatings, despite an increase in porosity, which however does not exceed 1%. The tribological performance of the four coatings is investigated using a pin-on-disk test, demonstrating that the coating wear resistance behaviour improved as the IN 718 content increased. Analysis of the wear mechanism shows that C4 coating has a different wear behaviour than the other coatings, thus achieving the best wear-resistance performance.

Abstract: Bentonite was modified through intercalation and calcination using a ZrOCl₂ pillaring solution. To create nano Ni/ZrO₂-bentonite catalyst, ZrO₂ pillared bentonite was impregnated using Ni(NO₃)₂•6H₂O precursor first, then followed by calcination and reduction. The physical-chemical properties of the catalyst was characterized by XRD (X-ray Diffractometer), FT-IR (Fourier Transform Infrared), surface acidity with NH₃ vapor adsorption method, SAA (Surface Area Analyzer) and TEM (Transmission Electron Microscope). The results of characterization with XRD showed specific peaks for montmorillonite minerals with a monoclinic crystalline type and its chemical composition (Ca)(Al,Mg)₆(Si₄O₁₀)₃(OH)₆.nH₂O and after pillarization showed a shift in basal spacing d₀₀₁ to the left (angle 2θ <5°). The typical peak indicating basal spacing d₀₀₁ shift towards a smaller angle of 2θ was not very apparent after impregnation with nickel metal. Qualitative determination of acidity after adsorption of ammonia showed characteristics at 1404-1635 cm^-1 wavenumbers with increasingly sharp spectra indicating increased acidity of the catalyst (Brǿnsted and Lewis acids). Surface area showed a significant increase from 27.385 m²/g to 174.208 m²/g after pillarization and impregnation of nickel metal.

Abstract: This paper describes the reduction of nickel oxide under different gas mixture. The influence of gas mixture on phase, density, morphology and pore size of reduced nickel oxide were studied. Nickel oxide pellets sintered at 1400 °C were reduced under various hydrogen-nitrogen gas mixtures, namely 40% H₂-60% N₂, 60% H₂-40% N₂, 80% H₂-20% N₂. Phase identification, density measurement and observation of morphology were conducted on samples before and after reduction process. Under all gas mixtures, nickel oxide was completely reduced to nickel. Density of the samples decreased in the range of 21% to 32% depends on H₂ percentage used. Results from the density shows that the higher the H₂ gas concentration, the smaller the density changes. Significant change in porosity of the sample before and after reduction was observed. Size of pore after reduction determined by H₂ concentration used during reduction where the higher the H₂ concentration resulted in large pore size.

Abstract: In this work, we have investigated the localized surface plasmon resonance profile of promising non-noble metals such as nickel (Ni), iron (Fe), and permalloy (Ni₈₀Fe₂₀) as an alternative plasmonic material. The nanoparticle formed a sphere with varying the diameter from 10 nm to 200 nm with increment 10 nm, and the medium of nanoparticles is air (1+0i). The calculation was carried out by metallic nanoparticle boundary element method package. Furthermore, our result shows that increasing diameter of particles (iron, nickel, and permalloy) would increase the efficiency of ratio scattering to absorption, and the LSPRs peak led to shift to lower energy (red-shift). The ratio of scattering to absorption indicates a strengthening of radiative damping in large particle-size which largely used in biological cell imaging. However, iron’s efficiency much lower than nickel and permalloy. For example, at the highest diameter, such 200 nm, the efficiency of iron is just over around 1.25 while nickel and permalloy well under nearly 2.0. In addition, nickel and permalloy’s LSPR happened in visible range. Our results serve a systematic understanding of the shifting spectrum pattern for prospective ferromagnetic materials

Abstract: The scope of this study was to ascertain the weldability of Nickel 201 alloy sheets using an electron beam welding method. Weld joints of the Nickel 201 alloy sheets 2,0 mm thick were welded by electron beam without an additional material at a flat position. The influence of electron beam welding parameters on weld quality and mechanical properties of test joints was studied. The study of quality and mechanical properties of the joints were determined by metallographic evaluation, tensile and hardness tests.

Abstract: This article present the results of studies of the process of wire drawing from the PdNi-5 alloy, performed using computer simulation in the DEFORM 3D software package. В качестве материала для исследований использовали сплав с содержанием 95% палладия и 5% никеля. An alloy with a content of 95% palladium and 5% nickel was a material for research. The patterns of changes in the stress-strain state for the current processing mode determined, and a more rational drawing mode with a redistribution of drawing coefficients along transitions proposed. For the proposed regime, using the created model, the values of drawing stresses, drawing forces and Cockcroft-Latham criterion determined. It was found that the stress distribution in the deformation zone corresponds to the generally accepted laws of their change, and their maximum values are realized in the metal located in the calibrating zone of the drawing die. In addition was revealed that the stresses in the current mode have limit values at the second and fourth passes. The redistribution of deformation indicators in the proposed mode allowed reduce the magnitude of these stresses and, thereby, reduce the likelihood of wire breaks. The maximum value of the Cockcroft-Latham criterion is achieved in the last transitions, but at the same time, destruction will not occur, since they do not exceed the limit value. The drawing force also decreases with the implementation of the proposed mode and does not exceed the permissible values regulated by the technical characteristics of the equipment. Since it is the proposed mode of wire drawing, it is characterized by a decrease in energy power indicators and the likelihood of wire breakage in the process of metal deformation it can be recommend it for implementation in existing production.

Abstract: The content of elements in the main mineral components of the ore, such as serpentine, talc, and chlorites, were determined. It was shown that, during heat treatment of the ore, in addition to the decomposition of hydrates and carbonates, serpentine decomposes and new phases (forsterite and enstatite) form. On the bases of analysis of the properties of the ore, patterns of phase transitions during heated in inert and reducing atmosphere were identified. It was found that the coal-thermal reduction of nickel and iron from oxides begins at temperatures above 800 °C, and from serpentines begins at temperatures above 1250 °C. It was found that, when heating the ore above 1200 °C in a mixture with a reducing agent, the metals reduce and form iron-nickel alloy. During electro-thermal smelting, the mode of which was determined by the melting points of slag (SiO₂ – MgO – FeO – CaO – Al₂O₃ system) and ferronickel, the ratio of Ni / Fe in the metallic phase was determined by the consumption of reducing agent (coal, coke).