Ni Metal Powder Research Articles

Cold Spray Deposition of MoS2- and WS2-Based Solid Lubricant Coatings

The cold spray deposition technique has been used to produce a new class of solid lubricant coatings using powder feedstocks of the metal disulfides WS2 or MoS2, either pure or mixed with Cu and Ni metal powders. Friction and cycle lives were obtained using ball-on-flat reciprocating tribometry of coated 304 SS flats in dry nitrogen and vacuum at higher Hertzian contact stresses (Smax = 1386 MPa (201 ksi)). The measured friction and thickness of the coatings were much lower than for previous studies (COF = 0.03 ± 0.01 and ≤1 µm, respectively), which is due to their high metal disulfide:metal ratios. Cu-containing metal sulfide coatings exhibited somewhat higher cycle lifetimes than the pure metal sulfide coatings, even though the Cu content was only ~1 wt%. Profiling of wear tracks for coatings tested to 3000 cycles (i.e., pre-failure) yielded specific wear rates in the range 3–7 × 10−6 mm3N−1m−1, similar to other solid lubricant coatings. When compared to other coating techniques, the cold spray method represents a niche that has heretofore been vacant. In particular, it will be useful in many precision ball-bearing applications that require higher throughput and lower costs than sputter-deposited MoS2-based coatings.

Optimization of TLPS Bonding Process and Joint Property using Ni-Sn Paste for High Temperature Power Module Applications

Recently, as interest in eco-friendly vehicles such as electric and hybrid vehicles increases, the demand for power semiconductors, a key component, is also increasing. Power semiconductors convert, distribute, and control power and operate in harsh environments such as high temperature and high pressure. In order to ensure stable reliability in such harsh environments, research on a technology that can stably form joints even at high temperatures is essential. Transitional liquid phase (TLP) bonding was proposed as a high-temperature power semiconductor chip bonding technology, which has the advantage of forming an intermetallic compound (IMC) phase with a high melting point at the joint. However, it takes a long time to convert the joint into full IMC phase. Therefore, in this study, in order to shorten the process time, a paste was manufactured by mixing high-melting point Ni metal powder and low-melting point Sn metal power, and a joint was formed through a TLPS (Transition liquid phase sintering) bonding using the paste. Pastes of different compositions were prepared by adjusting the ratio of Ni and Sn powders. The chip and substrate were bonded through a thermocompression (TC) bonding process, and the highest shear strength was obtained at a bonding temperature of 250 ℃ for 10 min. Heat treatment was performed at 200 ℃ for up to 500 h to evaluate the high temperature long-term reliability of the joints. The Ni-Sn TLPS bonded joints remained reliable joints after a long-term aging test at a high temperature of 200 ℃.

Boosting the overall electrochemical water splitting performance of pentlandites through non-metallic heteroatom incorporation

SummaryWe report on synthesis of the heterotrimetallic pentlandite-type material Fe3Co3Ni3S8 (FCNS) in presence of suitable phosphorus-(FCNSP) and nitrogen-(FCNSN) donors for the overall electrochemical water splitting. Throughout the experiments, a preferential incorporation of N into the FCNS-lattice is observed whereas the addition of phosphorus generally leads to metal-phosphate-FCNS composites. The obtained FCNSP, FCNSN, and FCNSNP facilitate the oxygen evolution reaction (OER) at 100 mAcm−2 in 1.0M KOH with overpotentials of 479, 440, and 427 mV, respectively, outperforming the benchmark IrO2 (564 mV) and commercial Ni metal powder (>600 mV). Likewise, FCNSN and FCNSNP reveal an improved performance toward the hydrogen evolution reaction (HER) in 0.5M H2SO4, outperforming the pristine FCNS. All materials revealed high stability and morphological robustness during OER and HER. Notably, DFT calculation suggests that N and P doping boost the OER activity of the pristine FCNS, whereas N doping enhances the HER activity.

SHS compaction of TiC cermets using mechanically activated mixtures

This paper focuses on obtaining cermet composite materials by SHS compaction. The study covers the effect of mechanical activation of metal components contained in reaction mixtures based on the Ti + C + Cr + Ni system when treated with grinding media in a ball mill. Two mechanical activation methods were used for Ti, Cr and Ni metal powders. In the first method, Cr and Ni powders were activated with grinding media separately from other reaction mixture components, and then mixed with titanium and carbon black powders. It is shown that the preliminary mechanical activation of inert components reduces the temperature and rate of combustion and increases the average size of carbide grains. In the second method, Ti + + Cr, Ti + Ni, and Ti + Cr + Ni powder mixtures were jointly processed in a ball mill, and then mixed with carbon black. This method provided mechanical activation of titanium particles with a minimum effect of grinding media on Cr and Ni powders. This led to an increase in the combustion rate and temperature, a decrease in the average size of carbide grains, and an increase in the composite structure homogeneity. A mechanism is proposed for the interaction of reagents (Ti + C) with the participation of activated Cr and Ni particles in combustion and structure formation zones, according to which the mechanical activation of inert components leads to their direct participation in the reaction interaction of titanium with carbon, which determines a decrease in the combustion rate and temperature and affects the fineness and structural homogeneity of compact composites. The results obtained were used to increase the structural homogeneity and fineness of the STIM-3B composite (Grade 3B synthetic hard tool material).

Fabrication of a Full-Scale Pilot Model of a Cost-Effective Sodium Nickel-Iron Chloride Battery Over 40 Ah

To fabricate a full-scale pilot model of the cost-effective Na–(Ni,Fe)Cl2 cell, a Na–beta–alumina solid electrolyte (BASE) was developed by applying a one-step synthesis cum sintering process as an alternative to the conventional solid-state reaction process. Also, Fe metal powder, which is cheaper than Ni, was mixed with Ni metal powder, and was used for cathode material to reduce the cost of raw material. As a result, we then developed a prototype Na–(Ni,Fe)Cl2 cell. Consequently, the Ni content in the Na–(Ni,Fe)Cl2 cell is decreased to approximately (20 to 50) wt.%. The #1 prototype cell (dimensions: 34 mm × 34 mm × 235 mm) showed a cell capacity of 15.9 Ah, and 160.3 mAh g−1 (per the Ni–Fe composite), while the #2 prototype cell (dimensions: 50 mm × 50 mm × 335 mm) showed a cell capacity of 49.4 Ah, and 153.2 mAh g−1 at the 2nd cycle.

Influence of Hardening Additives on the Characteristics of the Tribological TiC–Al2O3 Ceramic Composite Obtained by SHS

Addition of various reinforcements was studied in an attempt to produce a TiC–Al2O3 composite with high density, homogeneous microstructure, and outstanding mechanical properties for use in aggressive media using self-propagating high-temperature synthesis (SHS). Ductile Ni-metal powder (5 – 20 wt.%) and Al2O3 and ZrO2 (1 mole fraction) dilutions with and without Ni addition were introduced into TiC–Al2O3 composite synthesized by combined SHS and direct consolidation (DC). The influence of the Ni content and dilution with Al2O3 and ZrO2 on the phase composition, densification behavior, microstructure, and mechanical properties of the synthesized TiC–Al2O3 composite was investigated. The best results were obtained by adding Ni(5 wt.%) to the TiC–Al2O3 composite. However, the chemical reactions between the starting precursors were disturbed and the composite characteristics worsened if the Ni content was increased to >5 wt.%. Accordingly, addition of 5 wt.% Ni was suggested to produce a highly dense TiC–Al2O3 composite with a homogenized morphology and unparalleled mechanical properties. Moreover, the produced composites could be used successfully in aggressive media and tribological applications.

Microstructural characterization and mechanical properties development with Ti, Cr, or Ni addition for low carbon steel butt joints

Welding is one of the most important industrial process, therefore many practical techniques are developed to obtain an efficient and cost effective welding for different kind of metals. In this research, the microstructural characterization and mechanical properties of welded joints using TIG welding were studied for 1020 AISI low carbon steel. Titanium, Chromium, or Nickel powder were added to the welded joint one at a time by paste it with paraffin wax in the form of a thin layer. The welds were conducted and tested, then results were compared with and without adding Ti, Cr, or Ni metal powder. The welding process was done at a constant DC current (200 Amps. and 20 Volts) using weld filler metal type ER70S-3. Tests results showed that the tensile strength of the welded joint without adding metal powders was approximately 2% higher than the tensile strength of the base metal. Additionally, the tensile strength enhanced by approximately 27%, 21%, and 2% for Titanium, Nickel, and Chromium metal powder addition to the welded joints respectively. The bending strength values for all welded joints were also higher than the base metal. Furthermore, the hardness values were increased in the welded zone for all specimens. This can be attributed to the difference in the behavior of each metal powder at high temperature. The obtained results provide an experimental reference for the development of a new welding technique. It can be used in practical welding applications to obtain the desired properties using a suitable metal powder or a combination of them.

Synthesis of Magnesium Nickel Boride Aggregates via Borohydride Autogenous Pressure.

We demonstrate synthesis of the ternary intermetallic MgNi3B2 using autogenous pressure from the reaction of NaBH4 with Mg and Ni metal powder. The decomposition of NaBH4 to H2 and B2H6 commences at low temperatures in the presence of Mg and/or Ni and promotes formation of Ni-borides and MgNi3B2 with the increase in temperature. MgNi3B2 aggregates with Ni-boride cores are formed when the reaction temperature is >670 °C and autogenous pressure is >1.7 MPa. Morphologies and microstructures suggest that solid–gas and liquid–gas reactions are dominant mechanisms and that Ni-borides form at a lower temperature than MgNi3B2. Magnetic measurements of the core-shell MgNi3B2 aggregates are consistent with ferromagnetic behaviour in contrast to stoichiometric MgNi3B2 which is diamagnetic at room temperature.

Addressing aquatic hazard classification for metals, metal compounds and alloys in marine systems

New International Maritime Organization regulations require shippers to classify all solid bulk cargo to indicate whether they are Harmful to the Marine Environment (HME). The objective of this work was to adapt the freshwater Transformation/Dissolution Protocol (T/DP) to marine water to provide a method to determine, when compared with marine Ecotoxicity Reference Values (ERVs), whether a metal-bearing substance is HME. The substances examined were: Cu2O powder; Ni metal powder; Co3O4 powder; and a Ni–Co–Fe alloy, as wire cuttings, which were the same substances examined in the freshwater T/D validation study and afforded comparisons of the reactivity, or measure of the rate and extent of metal release from the metal-bearing substances in freshwater versus marine conditions. The marine T/D method is suitable for conducting examinations of metal-bearing substances with a wide range of reactivities, from the relatively reactive Cu2O powder and the alloy to the Co3O4 powder, which was the least reactive.

Structural, Thermal and Magnetic Properties of Nanocrystalline Co80Ni20 Alloy Prepared by Mechanical Alloying

Co80Ni20 powder mixture was mechanically alloyed by high-energy planetary ball milling, starting from elemental Co and Ni metal powders. The morphological, microstructural, thermal and magnetic properties of the milled powders were characterised respectively by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and vibratory sample magnetometry. In addition to a highly disordered phase, two face-centred cubic (FCC) and hexagonal close-packed (HCP), solid solutions, FCC Co(Ni), FCC Ni(Co) and HCP Co(Ni), are observed after 3 h of milling. Their grain sizes decrease with increase in milling time attaining, at 48 h of milling, 12 nm, 25 nm and 10 nm, respectively. Beyond a certain milling time, no further refinement of the microstructure occurs and the morphological equilibrium is usually given by a bimodal particle size distribution. Magnetic measurements of the milled Co80Ni20 alloy powder exhibit a soft ferromagnetic character where the magnetic parameters are sensitive to the milling time mainly due to the particle size refinement as well as the formation of Co(Ni) and Ni(Co) solid solutions. Both the saturation magnetisation ( Ms) and coercivity ( Hc) were found to decrease with milling time, attaining the values of Ms = 126 emu/g and Hc = 60 Oe after 48 h of milling.

Investigation on the thermodynamic analysis, preparation and characterization of LaNi5 - hydrogen storage alloy by magnesiothermic reduction diffusion process

The present investigation focuses on the preparation of LaNi5 intermetallic compound by ?Metallothermic reduction diffusion process?. Experiments were carried out using oxides and chlorides of La and Ni metal powders as the raw materials with granular Mg powder as the reductant. The thermal reduction process was carried out at 900 ?C for 9 hrs in Ar atmosphere. After the completion of reaction, the contents were purified by treating with dilute acetic acid followed by de-ionized water. Thermodynamic feasibility studies were carried out to determine the probabilistic nature of formation of the desired compound. Thermal analysis was carried out to find the dissociation and decomposition temperature of the reactants. The phase purity and the elemental composition of the alloy were assessed by XRD and EDX analyses. The morphological features of the prepared powders were examined by SEM. From this study, it has been concluded that LaNi5 alloy can be prepared with an appreciable purity by the Metallothermic reduction diffusion process.

Preparation of La-Mg-Ni Hydrogen Storage Composite Alloys by Mechanical Alloying

LaNi5-xwt%Mg hydrogen storage alloys with different Mg content were made from pure La, Mg and Ni metal powder by mechanical alloying, selecting appropriate ball-milling parameters in 0.4MPa hydrogen atmosphere. The characterizations for hydrogen storage alloy show that a multi-phase alloy composed of MgH2, LaH3, Mg2NiH4 and Ni was obtained, the alloy have two hydrogen desorption temperature range, and the alloy with 25wt% Mg content can desorb hydrogen up to 4.02wt%.

Oxidation in CSPV experiments involving H2O-bearing mafic magmas: Quantification and mitigation

A difficulty in performing high-temperature (>900 °C) experiments on near-liquidus hydrous mafic melts in gas-medium cold-seal pressure vessels (CSPV) is the tendency for H 2 O in the fluid phase to dissociate and H 2 to diffuse through capsule material, leading to progressive oxidation of sample material. Negative consequences include premature stabilization of Fe-Ti oxide phases and commensurate deviation of the liquid line of descent toward silica enrichment. Moreover, time-variance of an intensive variable equal in importance to temperature or total pressure is an unwanted feature of any experimental study. Methodologies commonly employed to mitigate the oxidation problem, not without their own drawbacks, include incorporating CH 4 into the pressurizing gas, limiting run duration to 24 h, enclosing samples in Au-alloy capsules, and incorporating solid buffering assemblages to serve as indicators of f O₂ excursion. Using the Co-Pd-O system as a f O₂ sensor, we investigated progressive oxidation of basaltic andesite at 1010 °C and P H₂O = 150 MPa. Our time-series of 12, 24, 36, 48, and 60 h run durations reveals that oxidation occurs at a very high rate (~3-4 log unit change in f O₂ in 48 h). Both the variability of f O₂ and magnitude of dehydration-oxidation are considered unacceptable for phase equilibria work. Incorporation of additional CH4 serves only to offset the progressive oxidation trend toward a lower absolute range in f O₂ . Ultimately, rapid oxidation in CSPV hinders the chemical equilibration of experimental charges. To mitigate the issue, we propose the following solution: Incorporation of a substantial mass of Ni metal powder as an O 2 getter to the outer capsule successfully: (1) slows down oxidation; (2) stabilizes f O₂ at the nickel-nickel oxide (NNO) buffer after ~20 h; and (3) allows compositions to approach equilibrium. Runs much longer than 48 h may require one or more steps involving quenching and re-filling the pressure system with CH 4 .

Study on Thermal and Strain Behaviour in Selective Laser Sintering Process

This paper investigates thermal and strain behaviour in the selective laser sintering process with a mixture of SCM, Cu and Ni metal powder. In-process monitoring of strain change and temperature at the base plate is proposed in order to investigate thermal and strain behaviour induced by selective laser sintering. A strain gauge was attached to the bottom surface of the base plate while a thermocouple was inserted at a distance of 2 mm from the top surface of the base plate. Changes in the strain and the base plate temperature were observed using an oscilloscope during the laser sintering process. The results showed that the development of strain within the sintered structure was affected by the processing temperature. Besides that, after the laser sintering process was completed, the strain value increased gradually and became constant as it reached room temperature. This strain value was found to correspond with the test models deformation. In addition, the effects of laser scanning direction and laser energy density during the process were observed. Measurement of the test models deformation was also carried out to discover its relationships to strain change and processing temperature. The results showed that the sintered structure produced by laser scanning of a sector along the width induced less residual strain, which resulted in less deformation. In contrast, both residual strain and deformation were found to be higher when the laser scanning was carried out along the length. Furthermore, when a low laser energy density was used, less deformation of the sintered structure could also be obtained.

Hydrogen permeation of Y2O3–CuO–CeO2/Ni composite membrane

For the purpose of improving hydrogen permeation, Y2O3–CuO–CeO2 (YCC) mixed oxides were successfully prepared using the sol–gel method with and without oxalic acid. The obtained powder was characterized by XRD, TG/DTA, BET and FE-SEM techniques. The YCC mixed oxide with 10wt.% Ni metal powder as a composite membrane was prepared by hot-press sintering method (HPS) with a mechanical alloying process. The hydrogen permeation test of YCC/10wt.% Ni membrane was measured at room temperature with increasing pressure. Hydrogen permeation flux through a YCC/10wt.% Ni membrane was obtained at 7.7×10−7mol/m2s. Reaction enthalpy was calculated as −1.24J/mol using Arrhenius's plot.

Processes observed in high-energy systems comprising nanodimensional metal powders

Results of experimental investigations of structural changes in nanodimensional Al, Ti, Zn, Fe, Cu, and Ni metal powder agglomerates in the process of manufacturing solid-fuel systems are presented. Regular processes of metal powder interaction with polymer solutions during mixing and oxidation in the regime of programmable linear heating are described.

Advances in metals classification under the united nations globally harmonized system of classification and labeling

This article shows how regulatory obligations mandated for metal substances can be met with a laboratory-based transformation/dissolution (T/D) method for deriving relevant hazard classification outcomes, which can then be linked to attendant environmental protection management decisions. We report the results of a ring-test at 3 laboratories conducted to determine the interlaboratory precision of the United Nations T/D Protocol (T/DP) in generating data for classifying 4 metal-bearing substances for acute and chronic toxicity under the United Nations Globally Harmonized System of Classification and Labelling (GHS) criteria with respect to the aquatic environment. The test substances were Ni metal powder, cuprous oxide (Cu(2) O) powder, tricobalt tetroxide (Co(3) O(4) ) powder, and cuttings of a NILO K Ni-Co-Fe alloy. Following GHS Annex 10 guidelines, we tested 3 loadings (1, 10, and 100 mg/L) of each substance at pH 6 and 8 for 7 or 28 d to yield T/D data for acute and chronic classification, respectively. We compared the T/DP results (dissolved metal in aqueous media) against acute and chronic ecotoxicity reference values (ERVs) for each substance to assess GHS classification outcomes. For dissolved metal ions, the respective acute and chronic ERVs established at the time of the T/D testing were: 29 and 8 µg/L for Cu; 185 and 1.5 µg/L for Co; and 13.3 and 1.0 mg/L for Fe. The acute ERVs for Ni were pH-dependent: 120 and 68 µg/L at pH 6 and 8, respectively, whereas the chronic ERV for Ni was 2.4 µg/L. The acute classification outcomes were consistent among 3 laboratories: cuprous oxide, Acute 1; Ni metal powder, Acute 3; Co(3) O(4) and the NILO K alloy, no classification. We obtained similar consistent results in chronic classifications: Cu(2) O, Ni metal powder, and Co(3) O(4) , Chronic 4; and the NILO K alloy, no classification. However, we observed equivocal results only in 2 of a possible 48 cases where the coefficient of variation of final T/D concentrations masked clear comparisons with ERVs. Results support the validity and interlaboratory precision of the United Nations T/DP in establishing GHS classification outcomes for metals and metal compounds and support its use in regulatory hazard-based systems. Drawing on T/D data derived from laboratory testing of the metal-bearing substance itself, the T/D approach can be applied to establish scientifically defensible decisions on hazard classification proposals. The resulting decisions can then be incorporated into environmental management measures in such jurisdictions as the European Union.

Preparation and fluorescence properties of novel alkaline earth silicate phosphors by reduction treatment of Eu3+ to Eu2+

The synthesis and emission spectrum control of novel Eu2+-activated amorphous alkaline earth silicate phosphors from the reduction of Eu3+-activated amorphous alkaline earth silicate phosphors is reported. The as-prepared Eu3+-activated amorphous alkaline earth silicate phosphors emitted red. Reduction using Ni-metal powder in a H2 (5%)/Ar (95%) atmosphere produced Eu2+-activated amorphous barium silicate phosphor that emitted green. Eu2+-activated amorphous calcium silicate was produced by reduction with ammonium chloride in air and emitted purple-blue. It was possible to control the emission spectrum by changing the reduction time. These results suggest the possibility to use three-band type phosphors for the fabrication of white light emitting diodes using one host crystal.

Materials issues in the development of a long life alkaline fuel cell electrode

Typical domestic requirements call for system capable of outputting about 1 kW of electrical power on a continuous or intermittent basis and about 1 kW of heat. The alkaline fuel cell approach is suitable because of its potential for low cost and ruggedness. Apart from the issue of overall cost, the principal technical issue is to develop a cost effective long life 40,000 hour electrode. In this article we describe the construction of electrodes from Ni metal powder by compression and electroless deposition of Ni metal, effectively sintering the particles. These techniques can be applied to very high surface area Ni nano particles which should dramatically improve the electrode performance.

Materials issues in the development of a long life alkaline fuel cell electrode

Typical domestic requirements call for system capable of outputting about 1 kW of electrical power on a continuous or intermittent basis and about 1 kW of heat. The alkaline fuel cell approach is suitable because of its potential for low cost and ruggedness. Apart from the issue of overall cost, the principal technical issue is to develop a cost effective long life 40,000 hour electrode. In this article we describe the construction of electrodes from Ni metal powder by compression and electroless deposition of Ni metal, effectively sintering the particles. These techniques can be applied to very high surface area Ni nano particles which should dramatically improve the electrode performance.