Search Results (242)

Nickel is used in aerospace, military, energy, and chemical sectors. Commercially pure (CP) Ni, and its alloys, including solid-solution strengthened (SSS), precipitation strengthened (PS), and specialty alloys (SA), are widely utilized, typically at elevated temperatures, in corrosive settings and in cryogenic milieu. Ni or Ni-based alloys frequently require welding realized, inter alia, via methods using electric arc and beam power. Tungsten inert gas (TIG) and Electron-beam welding (EBW) have been utilized most often. Friction stir welding (FSW) is the most promising solid-state welding technique for connecting Ni and its alloys. The primary weldability issues related to Ni and its alloys are porosity, as well as hot and warm cracking. CP Ni exhibits superior weldability. It is vulnerable to porosity and cracking during the solidification of the weld metal. Typically, SSS alloys demonstrate superior weldability when compared to PS Ni alloys; however, both types may experience weld metal solidification cracking, liquation cracking in the partially melted and heat-affected zones, as well as ductility-dip cracking (DDC). Furthermore, PS alloys are prone to strain-age cracking (SAC). The weldability of specialty Ni alloys is limited, and brazing might provide a solution. Employing appropriate filler metal, welding settings, and minimal restraint can reduce or avert cracking. Full article

Nickel matrix composites reinforced with T15 high-speed steel (HSS) were prepared using powder metallurgy techniques. A systematic investigation was conducted into the effect of CeO₂, MoS₂, and graphite additives on the tribological properties of the composites. The results show that when T15 HSS particles are added, nickel grains do not grow as much as they do in pure sintered nickel. It was also observed that the T15 HSS particles were diffusion-bonded to the nickel matrix after sintering. The highest relative density after sintering is obtained for composites containing graphite, but the maximum hardness of 243 HV can be achieved for composites containing 2% of CeO₂, which is about 16% higher than that of the Ni-T15 HSS composite. The wear rate of Ni-T15 HSS composites reduces from 3.4782 × 10⁻⁷ cm³/N∙m to 2.0222 × 10⁻⁷ cm³/N∙m as the content of CeO₂ rises from 0 wt.% to 2 wt.%. The wear mechanisms of composites with MoS₂ or graphite are abrasive wear and adhesive wear. The introduction of CeO₂ enhances the hardness of the investigated composites to the highest degree, leading to a change in the wear mechanism of the composites to slight abrasive wear. The addition of CeO₂ can effectively optimize the tribological properties of Ni-T15 HSS composites. Full article

Complex antimony pyrochlores Bi_2.7M_0.46Ni_0.70Sb₂O_10+Δ (M = Zn, Mg) were synthesized from oxide precursors, using the solid-state reaction method. For each composition variant, the pyrochlore phase formation process was studied during solid-state synthesis in the range of 500–1050 °C. The influence of zinc and magnesium on the phase formation process was established. The interaction of oxide precursors occurs at a temperature of 600 °C and higher, resulting in the formation of bismuth stibate (Bi₃SbO₇) as a binary impurity phase. Oxide precursors, including bismuth(III) and antimony(III,V) oxides, are fixed in the samples up to 750 °C, at which point the intermediate cubic phase Bi₃M_2/3Sb_7/3O₁₁ (sp. gr. Pn-3, M = Zn, Ni) is formed in the zinc system. Interacting with transition element oxides, it is transformed into pyrochlore. An intermediate phase with the Bi_4.66Ca_1.09VO_10.5 structure (sp. gr. Pnnm) was found in the magnesium system. The unit cell parameter of pyrochlore for two samples has a minimum value at 800 °C, which is associated with the onset of high-temperature synthesis of pyrochlore. The synthesis of phase-pure pyrochlores is confirmed by high-resolution Raman spectroscopy. The data interpretation showed that the cations in Ni/Zn pyrochlore are more likely to be incorporated into bismuth positions than in Ni/Mg pyrochlore. The nickel–magnesium pyrochlore is characterized by a low-porosity microstructure, with grain sizes of up to 3 μm, according to SEM data. Zinc oxide has a sintering effect on ceramics. Therefore, the grain size in ceramics is large and varies from 2 to 7 μm. Full article

Masked cold spray additive manufacturing (CSAM) is investigated for fabricating nickel-based electrodes with pyramidal pin-fins that enlarge the active area for the hydrogen-evolution reaction (HER). To bypass the high cost of purely CFD-driven optimization, we construct a two-stage machine learning (ML) framework trained on 48 high-fidelity CFD simulations. Stage 1 applies sampling and a K-nearest-neighbor kernel-density-estimation algorithm that predicts the spatial distribution of impacting particles and re-allocates weights in regions of under-estimation. Stage 2 combines sampling, interpolation and symbolic regression to extract key features, then uses a weighted random forest model to forecast particle velocity and temperature upon impact. The ML predictions closely match CFD outputs while reducing computation time by orders of magnitude, demonstrating that ML-CFD integration can accelerate CSAM process design. Although developed for a masked setup, the framework generalizes readily to unmasked cold spray configurations. Full article

Based on the concept of an equivalent eddy current, anomaly field inversion provides an efficient and rapid inversion method for borehole transient electromagnetic (BHTEM) measurements. It enables the utilization of the equivalent eddy current to rapidly process and interpret BHTEM data. This method allows for the accurate determination of the central position and spatial distribution of anomalies. However, the equivalent eddy current method is solely applicable to the inversion of the anomaly field. Given that the measured data frequently contain strong background field information, it is challenging to directly apply the equivalent eddy current approach to the inversion and interpretation of the measured data. To address the aforementioned issues, in this study, we innovatively put forward a method. Specifically, we utilize the response of the layered earth to simulate the background field and subtract the background field from the measured data through the “difference method” to extract the anomaly field. Subsequently, by integrating the equivalent eddy current method, the inversion of the anomaly field was accomplished. Eventually, a rapid quantitative inversion and interpretation of BHTEM data were achieved. We applied this approach to extract the pure anomaly from the measured data of the zk506 borehole in the Baishiquan mining area, Xinjiang, and then conducted equivalent eddy current inversion. The spatial position and distribution characteristics of the concealed ore bodies near the zk506 borehole were successfully pinpointed. Validation by the zk507 and zk508 boreholes confirmed that the main anomaly of the nickel ore body is positioned in the southeast of the boreholes, dipping northwestward. This outcome validates the accuracy of the BHTEM inversion interpretation and rectifies the geological understanding obtained from the zk506 single borehole. It demonstrates the effectiveness and significance of the pure anomaly extraction based on the layered-earth model and equivalent eddy current inversion in the exploration of high-conductivity sulfide ores. Full article

Wire electrochemical discharge machining (WECDM) integrates the effectiveness of electrical discharge machining (EDM) with the superior quality of electrochemical machining (ECM), leading to enhanced machining efficiency, excellent surface finish, and significant potential for advancement. However, previous research has mainly focused on the processing of non-metallic materials, with little research in the field of the microfabrication of thick metal materials. The wire electrochemical discharge machining process with large aspect ratios is more complex. Accordingly, a unidirectional traveling wire electrochemical discharge micromachining (UWECDMM) method using a glycol-based electrolyte was proposed. The method employs a glycol solution with low conductivity and a neutral salt, facilitating enhanced mass transfer efficiency through a unidirectional traveling wire, and enabling the realization of high-efficiency, high-precision, and recast-free processing. The phenomenon of discharge in UWECDMM was observed in real-time with a high-speed camera, while the voltage and current waveforms throughout the machining process were carefully analyzed. It was found that electrolysis and discharge alternate. Experiments were conducted to investigate the wire traveling pattern, the recast layer, and the wear of the wire electrode. It was found that due to the small energy of a single discharge, the wear of wire electrodes is minimal after multiple uses and can be reused. Under optimal parameters, a machined surface without a recast layer can be obtained. In the final stages, a standard structure was machined on plates of 10 mm thickness made of pure nickel and 304 stainless steel, using a tungsten wire measuring 30 μm in diameter. The feed rate achieved was 1 μm/s, the surface roughness (Ra) measured 0.06 μm, and the absence of a recast layer confirmed the method’s sustainability and quality traits, indicating significant potential in microfabrication. Full article

Electrodeposited composite coatings are widely studied for their potential to improve surface properties such as wear resistance and friction reduction. This study investigates the effect of electrodeposition parameters on the structure, morphology, and tribological performance of three coatings: pure nickel (Ni), Ni–graphite (Ni-G), and Ni–MoS₂ (Ni-MoS₂). Three deposition conditions were selected based on a review of key electrochemical parameters commonly used in the literature. The coatings were analyzed in terms of morphological characteristics, friction and wear resistance. The findings reveal that higher current densities led to increased friction and wear in Ni coatings, while lower pH values promoted finer crystallite sizes and improved tribological behavior. Ni-G coatings exhibited larger cluster formations with reduced friction and wear, especially at low pH, whereas Ni-MoS₂ coatings developed a stable cauliflower-like morphology at pH 2, but showed reduced adhesion and structural integrity at higher pH levels. Scratch resistance tests performed under optimal deposition conditions showed that Ni-G coatings provided the highest resistance to mechanical damage, while Ni-MoS₂ coatings were more susceptible to microcracking and adhesion failure. These results underscore the importance of optimizing deposition parameters to tailor the microstructure and functional properties of composite coatings for enhanced tribological and mechanical performance. Full article

We improved a scanning magnetic microscope built previously by adding a new detection system and the capability of mapping samples applying magnetic fields from −500 mT to +500 mT. The mechanical structure was also enhanced to decrease vibrations of the system in the earth’s magnetic field. The microscope is based on a differential arrangement of two Hall effect elements. The overall system presented a sensitivity of about 850 $n{T}_{rms}\surd Hz$, and it was calibrated using a 99% pure nickel sphere. The system achieved a magnetic moment sensitivity of the order of 10 nAm². All equipment used for operating the magnetic microscope was controlled by using the LabVIEW^® platform. We also fabricated samples with controlled properties using iron oxide microparticles and epoxy resin with various densities. We obtained the magnetization curves of the composites using the assembled microscope and compared them with the iron oxide powder. Full article

Leachates from electronic waste, slag dusts generated during the processing of electronic waste, sweeping jewelry, and municipal solid-waste incineration residues contain a myriad of base metals, such as aluminum (Al: 10–2000 mg/L), copper (Cu: 10–1000 mg/L), iron (Fe: 10–500 mg/L), nickel (Ni: 0.1–500 mg/L), lead (Pb: 1–500 mg/L), tin (Sn: 1–100 mg/L), and zinc (Zn: 5–500 mg/L), which are present at much higher quantities than Au (0.01–10 mg/L), which raises several drawbacks to the efficient recycling of Au with high purity using hydrometallurgical strategies. The aim of this work was to study the efficiency and selectivity of two strong basic anion exchange (DOW^TM XZ-91419.00 and Purogold^TM A194) resins to recover Au from a chloride multi-metal solution containing these metals. For both resins, the adsorption kinetic and equilibrium parameters for Au(III), determined at 1.12 mol/L HCl, Eh = 1.1 V, and 25 °C, proceeded according to a pseudo-second order and a Langmuir isotherm (qmax was 0.94 and 1.70 mmol/g for DOW^TM XZ-91419.00 and Purogold^TM A194 resins, respectively), respectively. Continuous adsorption experiments of Au (48 µmol/L; 2.0%) from a chloride multi-metal solution evidenced high Au retention capacity and selectivity to Au over Al, Cu, Fe, Ni, and Zn but low selectivity to Au over Ag and Sn for both resins. Concentrated (>3.3 mmol/L) and pure (>94%) Au eluates were obtained for both resins. Full article

In this study, PTA&PMA/NiMoO₄@NF was synthesized on nickel foam through wet chemical etching to promote the kinetics of the oxygen evolution reaction (OER) effectively. OER benefits from two cationic (Ni and Mo) defects and the optimized electronic configuration of PTA&PMA/NiMoO₄@NF. Thus, it only needs 200 mV to reach the current density of 10 mA cm⁻² in 1.0 mol/L of KOH. This value is nearly 100 mV lower than the value needed by pure NiMoO₄. After being used as an anode for water splitting in an alkaline solution, the as-obtained catalyst can operate at a current density of 10 mA cm⁻² for 24 h of good stability. The synthesis strategy adopted in this study can provide an effective, low-cost, simple, and convenient strategy for improving the OER electrocatalytic performance of other transition metal oxides. Full article

This study investigates the impact of nickel doping on the thermal and combustion properties of ammonium perchlorate/carboxymethyl cellulose (AP/CMC) composites. Through comprehensive SEM-EDS, FTIR, XRD, DSC, TGA, and burning rate analyses, significant improvements in the structural and functional characteristics of the AP/CMC-Ni composite were observed compared to those of pure AP and AP/CMC composites. The SEM-EDS analysis revealed that nickel incorporation resulted in thicker and more irregular CMC fibers, indicating substantial morphological changes. The FTIR spectroscopy showed shifts in the O-H and C=O stretching bands, pointing to interactions between nickel ions and CMC functional groups. The XRD patterns highlighted a decrease in crystallinity and the presence of NiO phases, confirming the successful integration of nickel into the CMC matrix. The thermal analysis demonstrated that nickel doping significantly lowered the decomposition temperature of the AP/CMC composite, as evidenced by DSC, and enhances the thermal degradation process, as shown by TGA. The AP/CMC-Ni composite exhibited a higher burning rate across all of the tested pressures, highlighting the catalytic effect of nickel in improving the combustion efficiency. The burning rate for AP/CMC follows the power-law expression with constants a = 2.34 and n = 0.499, while for AP/CMC-Ni, the constants are a = 3.35 and n = 0.475. This study highlights the essential role of nickel doping in facilitating the decomposition of AP within the AP/CMC composite. By lowering the decomposition temperature, nickel enhances the overall combustion process, making the AP/CMC-Ni composite more efficient for applications requiring controlled thermal decomposition. These findings provide valuable insights for the design and development of high-performance composite materials in advanced industrial applications. Full article

One of the main challenges in environmental remediation is the creation of stable and effective photocatalysts to eliminate organic contaminants when exposed to visible light. For the degradation of N-chloropiperidine, a persistent organic pollutant with multiple dangerous issues, we provide the synthesis, characterization, and photocatalytic evaluation of a Ni/NiO-incorporating carbon nitride (Ni/NiO-C₃N₄) composite in this work. The Ni/NiO-C₃N₄ photocatalyst was created by a single step of thermally polymerizing nickel nitrate and melamine. Four samples are ranged in Ni concentration from 0% to 10%. The coexistence of the Ni and NiO phases was confirmed by structural and morphological analyses using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). UV−Vis diffuse reflectance spectroscopy (DRS) also demonstrated an enhanced capacity to absorb visible light. A study of photocatalytic performance under visible light illumination showed that the Ni/NiO-C₃N₄ composite degraded N-chloropiperidine at a much faster rate than either pure carbon nitride (0.0231 min⁻¹), with a first-order rate constant of 0.0456 min⁻¹. The reaction rate nearly quadrupled when 10% Ni was added to the C₃N₄ matrix. Furthermore, the Ni/NiO-C₃N₄ composite’s photocatalytic activity performed better than its counterparts Ni-C₃N₄ (0.0315 min⁻¹) and NiO-C₃N₄ (0.0386 min⁻¹). The synergistic interaction between Ni and NiO, which promotes effective charge separation and lowers electron–hole recombination, is responsible for the higher activity of Ni/NiO-C₃N₄, increasing the production of reactive oxygen species. Furthermore, reusability experiments conducted over four successive cycles showed a slight decrease in activity, indicating the prepared samples are stable and reusable. Full article

In the field of non-silicon MEMSs (micro-electro-mechanical systems), nickel, with its mature preparation method, good compatibility with non-silicon MEMS processes, and excellent mechanical properties, is one of the commonly used structural materials. By effectively combining it with non-silicon MEMS processes, nickel is widely used in typical process systems such as LIGA (Lithography, Galvanoformung, Abformung)/UV-LIGA (Ultraviolet Lithography, Galvanoformung, Abformung). However, with the rapid development of the non-silicon MEMS field, pure nickel materials are no longer able to meet current material demands. Alternatively, nickel–cobalt composite materials have excellent mechanical properties, thermal stability, corrosion resistance, and good adaptability to processing technology because cobalt has unique advantages as a reinforcing phase, including excellent wear resistance, corrosion resistance, and high hardness. This article examines the current methods for preparing nickel–cobalt alloys by focusing on composite electrodeposition of coatings and analyzing their advantages and disadvantages. Based on this, the effect of the composite electrodeposition conditions on the formation mechanism of nickel–cobalt alloy coatings is discussed. Then, the research status of composite electrodeposition methods mainly based on nickel–cobalt nanocomposites is discussed. Finally, a new direction for future work on nickel–cobalt composite materials mainly composed of nickel–cobalt nanomaterials prepared by composite electrodeposition is proposed, and its application prospects in non-silicon MEMS fields are discussed. Full article

This study investigates the content of some metals and metalloids in the flowers of three Aesculus cultivars (AHP, Aesculus hippocastanum pure species, with white flowers; AHH, Aesculus hippocastanum hybrid species, with pink flowers; and AXC, Aesculus × carnea, with red flowers) over a four-year period (2016–2019) using inductively coupled plasma optical emission spectrometry (ICP OES) and principal component analysis (PCA). The research focuses on assessing macro- and micro-elemental compositions, identifying variations in mineral uptake, and exploring potential correlations with soil composition. Results highlight significant differences in elemental profiles among the three species, despite similar total ash content. Potassium and phosphorus emerged as dominant macroelements, with AXC showing lower magnesium levels compared to AHP and AHH. Particularly intriguing was the detection of antimony in all cultivars, raising questions about its role and bioaccumulation pathways in floral tissues. Iron and aluminum concentrations varied significantly across species, indicating species-specific metal transport mechanisms. Nickel content showed temporal fluctuations, potentially influenced by climatic conditions and soil properties. PCA revealed distinct clustering patterns, linking elemental concentrations to specific species and years. This comprehensive analysis enhances understanding of metal absorption and distribution in ornamental plants, providing insights into their metabolic processes and potential implications for environmental monitoring and phytoremediation strategies. Full article

Inconel 718 (In718) is the most widely used nickel-based alloy in additive manufacturing due to its favorable processability. However, In718’s high-temperature performance is not suited for the most demanding applications in the aerospace industry. Therefore, in this study, Inconel 718 powder was coated with 3% wt. rhenium (In718-Re) using AM’s in situ alloying capabilities to improve high-temperature properties. The proposed alloy’s mechanical performance was evaluated, focusing on the effects of post-process heat treatment and hot isostatic pressing following the laser-based powder bed fusion of metals (PBF-LB/M) processing. Static tensile tests conducted at room temperature and elevated temperatures (650 °C and 760 °C) demonstrated that the alloy has comparable strength to pure In718 according to ASTM F3055-14a—an ultimate tensile strength of 1247 MPa, yield strength of 909 MPa, and almost 2× higher elongation of 23.8%. Fatigue tests at room temperature indicated a fatigue limit below 400 MPa for 10⁷ cycles. Fractographic analysis revealed that fatigue performance was primarily impacted by a lack of fusion defects inherent to the PBF-LB/M process, highlighting the need for optimized powder preparation and processing parameters to minimize defect formation. While rhenium addition shows limited benefits in Inconel 718, this study underscores the potential of in situ alloying through powder surface modification as a flexible method for incorporating high-melting-point elements into nickel-based alloys for tailored alloy design in additive manufacturing. Full article