High-Q Magnetoelectric Nickel–Quartz–Nickel Structures

The results of experimental examination of the magnetoelectric parameters of three-layer nickel–quartz–nickel structures in the region of electromechanical resonance are presented. The structures have been fabricated by electrolytic deposition of nickel onto a quartz substrate. It has been found that their Q-factor in the region of electromechanical resonance is Q = 10000, which is considerably higher than the Q-factors of magnetoelectric structures fabricated earlier. The experimental data agree well with the earlier-presented theory.     

Synthesis and Characterization of Nickel Nanorods Transferred from Hydrotherally Decomposed Rod-like NiS

Powders of hexagonal-structured single-crystalline nickel sulfide nanorods have been synthesized in cetyltrimethy ammonium bromide （CTAB）/water/hexane/n-pentanol quaternary microemulsion under hydrothermal conditions by using the reaction of carbamide and carbon disulfide as a sulfide source. Single-crystalline nickel nanorods have been synthesized via thermal decomposition by using single-crystalline nickel sulfide nanorods as precursor. The influence of different reaction parameters on the morphology of the products has been investigated. The structure, morphology and magnetic properties of the products were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM）, calorimeter （TGA-DSC） and vibrating sample magnetometer showed that the specific saturation magnetization （σs） and 37.5 emu/g and 68.50e, respectively. thermogravimetric analysis-differential scanning （VSM）. The results of coercivity values （Hc） magnetic measurements of nickel nanorods were     

Reduction Kinetics of Nickel Sulphide

Reduction kinetics of Ni_3S_2 was experimen-tally studied by following the time required forcompletion of the hydrogen reduction reaction inthe presence of calcium oxide.A simple empiricalintegration equation,derived for describing the ef-fect of CaO/S molar ratio,temperature,hydrogenconcentration and the average diameter ofNi_3S_2 grains,may be shown as following:t|_(X=1)=2.317×10~(-6)d_(Ni_3S_2) C_(H_2)~(-1)β~(-2.29)e~(13710/T),minThe reduction reaction is of first order with respectto hydrogen concentration,and the apparent reac-tion activation energy is 114.0 kJ/mol.A great ma-jority of metallic Ni reduced from Ni_3S_2 is distrib-uted in the products evenly.     

Resistance Behaviour of Nanocrystal Nickel

The resistance behaviour of nanocrystal nickel was studied from 4 to 720 K and 0 to 20 Kbar.A linearvariation of the resistance was found at low temperatures.It showed that under high temperatures,that system transformed to a more stable state,with the relaxation process taking place by stages andinfluenced by exerted pressures.The property,especially the stability,of nanocrystal was closely re-lated to the compacting pressure,     

The biocompatibility of dense and porous Nickel–Titanium produced by selective laser melting

Nickel–Titanium shape memory alloys (NiTi-SMA) are of biomedical interest due to their unusual range of pure elastic deformability and their elastic modulus, which is closer to that of bone than any other metallic or ceramic material. Newly developed porous NiTi, produced by Selective Laser Melting (SLM), is currently under investigation as a potential carrier material for human mesenchymal stem cells (hMSC). SLM enables the production of highly complex and tailor-made implants for patients on the basis of CT data. Such implants could be used for the reconstruction of the skull, face, or pelvis. hMSC are a promising cell type for regenerative medicine and tissue engineering due to their ability to support the regeneration of critical size bone defects. Loading porous SLM-NiTi implants with autologous hMSC may enhance bone growth and healing for critical bone defects. The purpose of this study was to assess whether porous SLM-NiTi is a suitable carrier for hMSC. Specimens of varying porosity and surface structure were fabricated via SLM. hMSC were cultured for 8 days on NiTi specimens, and cell viability was analyzed using two-color fluorescence staining. Viable cells were detected on all specimens after 8 days of cell culture. Cell morphology and surface topography were analyzed by scanning electron microscopy (SEM). Cell morphology and surface topology were dependent on the orientation of the specimens during SLM production. The Nickel ion release can be reduced significantly by aligned laser processing conditions. The presented results clearly attest that both dense SLM-NiTi and porous SLM-NiTi are suitable carriers for hMSC. Nevertheless, before carrying out in vivo studies, some work on optimization of the manufacturing process and post-processing is required.     

Tribological Performance of Oil-soluble Nickel Octoxyborate

The tribological properties of oil-soluble nickel octoxyborate were evaluated using four-ball and ringon-block rigs. The results indicate that the wear resistance and load-carrying capacity of 500SN base oil were increased and its friction coefficient was decreased by the additive. The surface analysis of XPS indicates that nickel oxide,diboron trioxide,FeB and Fe2B have been deposited on the rubbing surface. It was these depositions that provided the oil with excellent antiwear and friction-reducing properties.     

Thermophysical Properties of a Chromium–Nickel–Molybdenum Steel in the Solid and Liquid Phases

Numerical simulation of vacuum arc re-melting, pressurized or protective electro-slag re-melting, and ingot casting have become quite important in the metal industry. However, a major drawback of these simulation techniques is the lack of accurate thermophysical properties for temperatures above 1,500 K. Heat capacity, heat of fusion, density, and thermal conductivity are important input parameters for the heat transfer equation. Since, direct measurements of thermal conductivity of alloys in the liquid state are almost impossible, its estimation from electrical conductivity using the Wiedemann–Franz law is very useful. The afore-mentioned thermophysical properties of several steels are investigated within the context of an ongoing project. Here, we present a full set of thermophysical data for the chromium–nickel–molybdenum steel meeting the standard DIN 1.4435 (X2CrNiMo18-14-3); these values will be used by our partner to simulate various re-melting and solidification processes. Wire-shaped samples of the steel are resistively volume-heated, as part of a fast capacitor discharge circuit. Time-resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe. The voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers, the temperature of the sample with a pyrometer, and the volumetric expansion of the wire with a fast acting CCD camera. These measurements enable the heat of fusion, the heat capacity, and the electrical resistivity to be determined as a function of temperature in the solid and liquid phases. The thermal conductivity and thermal diffusivity are estimated via the Wiedemann–Franz law.     

Preparation of Nickel Materials with Fractal Structure

A way of manufacturing nickel material with fractal structure has been studied. Some algae with natural fractal structure were used as the basic substrates. The nickel was coated on the substrates by both electroless deposition and electrodeposition. After elimination of the foundational algae by erosion, dissolution etc, the pure nickel materials with fractal structure were obtained. At last, the specific surface area was analyzed by BET analyses and the fractal dimension of the nickel material was calculated by means of box-counting technique. The comparison of fractal dimension between Ni structure and natural algae was also given.     

Effects of Vanadium and Niobium on the Phase Composition of Titanium-Carbonitride-Base Cermets with Titanium–Nickel Binder

The phase composition of V- or Nb-containing titanium-carbonitride-base cermets with a TiNi binder was investigated, and the content of the alloying metal in the refractory base of the alloys was determined. The alloys were found to consist of three phases: refractory phase, TiNi, and -Ni₂V₃ or Nb _z Ni. The solubility of V in titanium carbonitride is very low, while that of Nb is fairly high and increases with Nb content. The phase composition of the cermets is shown to correlate with the Gibbs energies of formation of the constituent carbides.     

A Hybrid Machining Process Combining Micro-EDM and Laser Beam Machining of Nickel–Titanium-Based Shape Memory Alloy

Micro-electrical discharge machining (EDM) is a slow process as compared to laser machining, on the contrary laser machining lacks good surface quality. To overcome the drawbacks of both these processes, this paper suggests a hybrid machining process which combines laser and micro-EDM processes for drilling microholes in advanced engineering materials such as Nickel–Titanium (Ni–Ti)-based shape memory alloy. To achieve the objective of the suggested hybrid process, pilot holes are drilled with laser machine and rimmed out by micro-EDM drilling. The suggested process requires investigation of various combinations of micro-EDM drilling process conditions to obtain optimum machining parameters for the hybrid process. It has been found that the proposed hybrid machining process resulted in 50–65% reduction in machining time without affecting the quality of microholes as compared to the standard micro-EDM process.     

Thermomechanical Fatigue Behaviour of a Nickel Base Superalloy

The isothermal low cycle fatigue (LCF)and thermomechanical fatigue (TMF) behaviourof a Ni-base superalloy was investigated. Theresults show that temperature plays an importantrole in both LCF and TMF. The alloy shows thelowest LCF fatigue resistance in the intermediatetemperature range (～760℃). For strain-controlledTMF, in-phase (IP) cycling is more damagingthan out-phase (OP) cycling. The high tempera-ture exposure in the TMF cycling influencesthe deformation behaviour at the low temperature.LCF lives at different temperatures, and IPand OP TMF lives are successfully correlatedby using the hysteresis parameter Δσ·Δε_p.     

Nickel Oxide as an Electrode Material for Supercapacitors

The preparation of Ni oxide films and their capacitive mechanism are discussed in this paper.Nickel oxide film electrodes perform pseudocapacitance in aqueous KOH and NaOH but perform double layer capacitance in LiClO4/PC(propylence carbonate).The effect of increasing the specific capacitance was observed when Ni oxide film electrodes are doped with Co.A specific capacitance of around 70 F/g was achieved when using Ni oxide films doped with Co as electrodes and 1mol/L aqueous KOH or NaOH as an electrolyte.     

Dealloying of a Nickel–Aluminum Bronze Impeller

A brackish water pump impeller was replaced after 4 years of service, while its predecessor lasted over 40 years. The subsequent failure investigation determined that the nickel–aluminum bronze (NAB) impeller was not properly heat treated, which made the impeller susceptible to aluminum dealloying. The dealloying corrosion was exacerbated by erosion, because the pump was slightly oversized. This investigation recommended proper heat treatment of NAB alloys that are to be used in salt water or brackish service. Additionally, the investigation recommended closer evaluation of new pumps to ensure that they are properly sized.     

Antiphase Boundary Strengthening in a Single Crystal Nickel—base Superalloy

An investigation has been made into strengthening mechanism in a single crystal nickel-base superalloy DD8 by transmission electron microscopy. The results show that the stress rupture strength of the alloy increases with decreasing misfit, and the antiphase boundaries (APBs) formed in the ordered γ' phase, rather than the misfits, play a dominate role in strengthening of the single crystal Ni-base superalloy DD8. There are three kinds of mechanisms for forming the APBs which were observed in the present materials. One is mis-arrangement of the local ordered atoms in the γ' precipitates due to the local strain; the second arises from the 1/2<110> dislocations cutting into the γ', and the third is the formation of the APBs induced by the 1/2<110> matrix dislocation network. The contribution of the antiphase boundary energy to the strength of the alloy can be expressed by: where τ is the resistance to deformation provided by the APB energy; S is the long-range order degree in γ'; Tc is the transition     

Nickel–zinc ferrite fabricated by sol–gel route and application in high-temperature superconducting magnetic energy storage for voltage sag solving

Ni–Zn ferrite nanoparticles of well controlled electromagnetic properties can be obtained through some chemical methods. In this study, the fine particles of Ni–Zn ferrite were prepared and fabricated using sol–gel route at low and high temperatures. The results gathered from the X-ray diffraction (XRD) indicated the amount of single-phase spinel ferrite constituents could be formed at a temperature below 400 °C. The Fourier transform-infrared spectroscopic (FT-IR) and the analyses using the microscopic photomicrographs were used to identify the formation of Ni–Zn spinel ferrite. The initial magnetic permeability showed that the inductance of the fabricated ferrite cores was of the highest value. Therefore, a laboratory coil equipped with a high-temperature superconducting magnetic energy storage (HT-SMES) was designed. The theoretical analysis of the torus with rectangular shaped coils was also carried out, and for this, a consideration for the average magnetic field inside the torus was used to calculate the inductance of the shape. Using uninterruptible power supply (UPS) and power conditioning system (PCS) which give details of the application of μ-SMES in solving voltage sag, a schematic diagram is also reported.     

Evolution of Carbonate-Intercalated γ-NiOOH from a Molecularly Derived Nickel Sulfide (Pre)Catalyst for Efficient Water and Selective Organic Oxidation

The development of a competent (pre)catalyst for the oxygen evolution reaction (OER) to produce green hydrogen is critical for a carbon-neutral economy. In this aspect, the low-temperature, single-source precursor (SSP) method allows the formation of highly efficient OER electrocatalysts, with better control over their structural and electronic properties. Herein, a transition metal (TM) based chalcogenide material, nickel sulfide (NiS), is prepared from a novel molecular complex [Ni^II(PyHS)₄][OTf]₂ ( 1 ) and utilized as a (pre)catalyst for OER. The NiS (pre)catalyst requires an overpotential of only 255 mV to reach the benchmark current density of 10 mA cm⁻² and shows 63 h of chronopotentiometry (CP) stability along with over 95% Faradaic efficiency in 1 m KOH. Several ex situ measurements and quasi in situ Raman spectroscopy uncover that NiS irreversibly transformed to a carbonate-intercalated γ−NiOOH phase under the alkaline OER conditions, which serves as the actual active structure for the OER. Additionally, this in situ formed active phase successfully catalyzes the selective oxidation of alcohol, aldehyde, and amine-based organic substrates to value-added chemicals, with high efficiencies.     

Pressure Effect on the Phase Transformations of a Nickel–Aluminum Alloy

Differential barothermal analysis is used to study the pressure effect (180 MPa) on the temperatures of phase transformations in a model nickel–aluminum alloy. The pressure coefficients for these transformations are larger than that for the melting point of pure nickel by a factor of 3–5.