Effect Of Ni Content Research Articles

Continuous Hydrothermal Flow Synthesis of Co1–xNixFe2O4 (x = 0–0.8) Nanoparticles and Their Catalytic Properties for CO Oxidation and Oxygen Evolution Reaction

Well‐crystallized CoFe2O4 and Ni‐substituted Co1–xNixFe2O4 nanoparticles (x = 0.1, 0.3, 0.4, 0.5, 0.6, 0.8) were synthesized by continuous hydrothermal flow synthesis (CHFS). Catalytic properties of the synthesized nanoparticles in the catalytic oxidation of CO and electrochemical oxygen evolution reaction (OER) were studied. A conversion of 50 % in CO was reached at 223 °C and 100 % at 310 °C when CoFe2O4 prepared by CHFS was used as catalyst. The effect of Ni content on the OER activity of the as‐synthesized Co1–xNixFe2O4 did not show a clear trend, however a remarkable improvement of the activity was observed for 30 at % substitution (x = 0.3) in Co0.7Ni0.3Fe2O4.

Effect of Ni content on the microstructure and mechanical behaviour of CrAlNiN coatings deposited by closed field unbalanced magnetron sputtering

Ni incorporation is known to impose an intriguing influence on the composition, microstructure and mechanical properties of nitride-based coatings prepared by physical vapour deposition. This work examined the effect of varying Ni concentrations, controlled by NiCr alloy target current (INiCr), on the microstructures and properties of CrAlNiN coatings deposited on to M2 tool steel substrates. These coatings were deposited by closed field unbalanced magnetron sputtering (CFUMS). The composition and structure of the as-deposited coatings were investigated by XPS, XRD, FIB, and TEM. Residual stresses were determined using the XRD-sin2ψ method. Nanoindentation tests were performed to assess mechanical properties of the CrAlNiN outer layer. At relatively low INiCr values, below 3 A, the grains within CrAlNiN layer underwent refinement, yet maintained a columnar structure. At higher INiCr values, from 3 to 5 A, the columnar grains transitioned into more equiaxed grains. Hardness values of 25–28 GPa at low INiCr values were associated with the high residual compressive stress, solid solution hardening and grain refinement.

Effects of Ni content on microstructure, mechanical properties and Inconel 718 cutting performance of AlTiN-Ni nanocomposite coatings

AlTiN-Ni coatings with various Ni contents (0–3 at%) were deposited using cathodic arc evaporation. X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, a nanohardness tester, scratch-adhesion tester, and cutting tester were used to examine the microstructure, mechanical properties, and cutting performance of the coatings. The AlTiN coatings exhibited a columnar structure, while the AlTiN-Ni coatings exhibited a nanocrystal structure due to the formation of nc-AlTiN/Ni nanocomposite coatings. The nanohardness of the AlTiN-Ni coatings decreased from 26.2 GPa to 20.9 GPa as the Ni content increased from 0 to 3 at%. At an Ni content of 1.5 at%, the coating possessed a high toughness and sufficient adhesion strength; however, these dropped drastically for the AlTiN-Ni coating with 3 at% Ni owing to the presence of amorphous Ni. The results for the Inconel 718 turning indicated that the wear mode is adhesion at the rake face, abrasion and adhesion (built-up edge) at the flank face, and chipping at the cutting edge. Compared to AlTiN-Ni3 and AlTiN-coated tools, the lifetime of the AlTiN-Ni1.5 coated tool increased to 160% at a cutting speed of 40 m/min. This was attributed to less adhesion at the rake face and chipping at the cutting edge, due to the nanocrystal structure and higher toughness of the AlTiN-Ni1.5 coating.

Hydrogen absorption and desorption behavior of Ni catalyzed Mg–Y–C–Ni nanocomposites

In order to improve the hydrogen storage properties of Mg-based materials, ternary Mg24Y3–3 wt.% graphite (C)–x wt.% Ni (x = 0–20) nanocomposites were synthesized by mechanical ball-milling. Micro-area elemental analysis shows that the Ni and C are evenly distributed in the samples. Effect of Ni content on hydrogen absorption and desorption behavior at various temperatures was performed. Hydrogenation leads to the in situ formation of YH2/YH3 and Mg2Ni/Mg2NiH4, which has a significant catalytic effect on the hydrogen absorption and desorption kinetics. Composites with more than 3 wt% of Ni can almost reach their maximum hydrogen storage capacity within 1 min at 100 °C. When the Ni content increases from 0 to 20 wt%, the dehydrogenation activation energy (Ea) is reduced to 58 kJ/mol, while the desorption peak temperature is also lowered down to 282 °C. Two equilibrium plateaus are clearly observed in pressure–composition isotherms (p–c–T) curves, which can be ascribed to the hydrogen absorption/desorption reactions of Mg/MgH2 and Mg2Ni/Mg2NiH4. In order to take account to the reversible hydrogen storage capacity and absorption/desorption kinetics, Mg24Y3–3 wt.% C–5 wt.% Ni composite is considered having the optimized hydrogen storage performance.

Effect of Ni Content on Iron-based Friction Material Prepared by In-situ Synthesized from Vanadium-bearing Titanomagnetite Concentrates

Effect of Ni Content on Iron-based Friction Material Prepared by In-situ Synthesized from Vanadium-bearing Titanomagnetite Concentrates

Microstructure and Properties of Ni/Al2O3 Composites Prepared by Powder Injection Molding

Ni/Al2O3 composite was prepared by powder injection molding, the effects of Ni content and different sintering process on the microstructure and mechanical properties of Ni / Al2O3 composites were studied. The results show that when the Ni content is 10%, the comprehensive performance of Ni / Al2O3 composite is better. The optimum vacuum sintering process of 10%Ni / Al2O3 composite is as follows: sintering temperature of 1500 °C for 1 hour, with the relative density of 96.7%, bending strength of 312 MPa, Vickers hardness of 1528HV and fracture toughness of 5.3 MPa•m1/2.

Effect of Ni Content on Microstructure and Characterization of Cu-Ni-Sn Alloys.

Cu-xNi-5Sn (wt %) alloys with a different Ni content were prepared by a powder metallurgy method. The effect of Ni content on the hardness and yield strength of Cu-xNi-5Sn (wt %) alloys was investigated. The microstructure, composition, and morphology of Cu-xNi-5Sn (wt %) alloys were observed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and cold field emission scanning electron microscope (FESEM), respectively. Results indicate that the hardness and yield strength firstly increase and then decrease with the increase of Ni content and reach up to a maximum when Ni content is 12.5 wt %. Furthermore, the formation of the sandwich structure and needle-like phase is found in the grain, the grain boundary and intragranular precipitates are rich in both the Ni and Sn phase. The formation of the inerratic and suitable lamellar precipitates of sandwich structure and needle-like phase can be responsible for the good mechanical properties of the Cu-12.5Ni-5Sn alloy after aging treatment. The sandwich structure and need-like phase that were observed by FESEM can contribute to clarify the morphology of Cu-Ni-Sn alloys.

NbC-Ni coatings deposited by DC reactive magnetron sputtering: Effect of Ni content on mechanical properties, thermal stability and oxidation resistance

Hard coatings have been widely used in the machine tool industry to increase the wear resistance and hence to improve their service lifetime, as a result of their better mechanical properties. Most of the studies focused more in nitrides and less in carbides. In this study, we evaluated the effect of Ni additions on the properties of NbC films deposited by magnetron sputtering. In particular, we investigated the microstructure, chemical composition, mechanical properties, oxidation resistance and thermal annealing of the films. The properties of Ni rich coatings were compared to a NbC film deposited as reference. All the films displayed a columnar morphology with columns extending from the substrate up to the surface. Increasing the Ni content decreases the NbC columns diameter and their level of compactness. Excluding the substrate contribution, all the diffraction peaks could be generally assigned to the fcc NaCl type structure. A progressive decrease of grain sizes, down to 2.5nm is observed, with Ni additions higher than 17at.% Ni, leading to a quasi-amorphous structure. Precipitation of a hexagonal NiCx phase led to an antagonistic shift of the (111) emphases and (200) NbC peaks to the right and to the left, respectively. The hardness of the films increased with increasing Ni content in the range of 0<at.% Ni<13 and then progressively decreased with further Ni additions. Annealing performed at 600 and 800°C increased the hardness and Young's modulus of the films. Plastic deformation resistance H3/E2 parameters also showed a growing trend with Ni additions. TGA measurements showed that Ni additions increased the oxidation performance of the coatings. The onset point of oxidation of the films is higher by 100°C for Ni containing films independently of the Ni amount, when compared to NbC nickel free films.

Effects of Ni content on the cast and solid-solution microstructures of Cu-0.4wt%Be alloys

The effects of Ni content (0–2.1wt%) on the cast and solid-solution microstructures of Cu-0.4wt%Be alloys were investigated, and the corresponding mechanisms of influence were analyzed. The results show that the amount of precipitated phase increases in the cast alloys with increasing Ni content. When the Ni content is 0.45wt% or 0.98wt%, needle-like Be21Ni5 phases form in the grains and are mainly distributed in the interdendritic regions. When the Ni content is 1.5wt% or greater, a large number of needle-like precipitates form in the grains and chain-like Be21Ni5 and BeNi precipitates form along the grain boundaries. The addition of Ni can substantially refine the cast and solid-solution microstructures of Cu-0.4wt%Be alloys. The hindering effects of both the dissolution of Ni into the matrix and the formation of Be–Ni precipitates on grain-boundary migration are mainly responsible for refining the cast and solid-solution microstructures of Cu-0.4wt%Be alloys. Higher Ni contents result in finer microstructures; however, given the precipitation characteristics of Be–Ni phases and their dissolution into the matrix during the solid-solution treatment, the upper limit of the Ni content is 1.5wt%–2.1wt%.

Effect of Ni content and Al2O3 particle size on the thermal and mechanical properties of Al2O3/Ni composites prepared by spark plasma sintering

Alumina-nickel composites were prepared by carrying out spark plasma sintering (SPS) of nano-sized and micro-sized Al2O3 particles with 15–45 wt% Ni powders. The powder materials were sintered at a temperature of 1400 °C under a constant uniaxial pressure of 50 MPa. FESEM micrographs of the products showed uniformly dispersed nickel inclusions in both matrices at intergranular positions. Presence of Al2O3 as the major phase along with Ni as the minor phase was confirmed using XRD analysis. Thermal and mechanical properties of the nano- and micro-sized Al2O3/Ni composites were investigated. The thermal conductivity of nano-sized alumina composites was seen to increase with the increase in nickel content, however, an opposite trend was observed for micro-sized alumina-based composites. Moreover, thermal conductivities of all the composites decreased with increase in temperature. The composites also showed high hardness and fracture toughness values of up to 19.6 GPa and 4.71 MPa ∗ m1/2, respectively, and relative density values, between 79 and 99%, that decreased with increasing Ni content. Furthermore, the nano-sized Al2O3/Ni composites showed thermal and mechanical properties superior to those of the micro-sized Al2O3/Ni composites.

CuCr1−xNixO2 thin films prepared by chemical solution deposition

CuCr1−xNixO2, (0.0 ≤ x ≤ 0.4) thin films were prepared on non-alkali glass substrates by chemical solution deposition. The effects of Ni content in CuCr1−xNixO2 thin films on the microstructural, optical, electrical, and magnetic properties were investigated. X-ray diffraction analysis revealed that all the samples presented the delafossite structure. The transmittance of the CuCr1−xNixO2 thin films was above 60% in the visible region, and the band gap was between 3.02 and 3.17 eV. It was found that the electrical resistance was decreased by increasing doping amount of Ni2+ ions. The lowest resistivity with relatively high carrier concentration was obtained in CuCr0.6Ni0.4O2 thin films. The experimental results imply that it is possible to get higher electrical conductivity of p-type transparent conducting oxides from CuCrO2 via doping with divalent ions.

Structural, Micromechanical and Tribological Characterization of Zn–Ni Coatings: Effect of Sulfate Bath Composition

Zn and Zn–Ni alloy coatings were electrodeposited on mild steel from sulfate-based bath containing Sn as additive. The effect of Ni content on the microstructure, morphology, microhardness and the tribological behavior of these coatings were studied and discussed. Adding Sn in the sulfate bath had a significant effect on the surface morphology, particularly on the Zn–8 wt% Ni coatings. By increasing the Ni concentration from 8 to 14 wt%, the X-ray patterns showed that the phase structure of Zn–Ni alloy coatings was changed from η-phase Ni3Zn22 to γ-phase Ni5Zn21. The plastic deformation and delamination were found to be wear mechanisms for the investigated coatings. While the Zn–14 wt% Ni alloys had the best wear resistance, Zn films had the most severe wear volume loss and the highest friction coefficient.

An Investigation on Hydrogen Storage Kinetics of the Nanocrystalline and Amorphous LaMg12-type Alloys Synthesized by Mechanical Milling

Nanocrystalline and amorphous LaMg12-type LaMg11Ni + x wt% Ni (x = 100, 200) alloys were synthesized by mechanical milling. Effects of Ni content and milling time on the gaseous and electrochemical hydrogen storage kinetics of as-milled alloys were investigated systematically. The electrochemical hydrogen storage properties of the as-milled alloys were tested by an automatic galvanostatic system. And the gaseous hydrogen storage properties were investigated by Sievert apparatus and a differential scanning calorimeter (DSC) connected with a H2 detector. Hydrogen desorption activation energy of alloy hydrides was estimated by using Arrhenius and Kissinger methods. It is found that the increase of Ni content significantly improves the gaseous and electrochemical hydrogen storage kinetic performances of as-milled alloys. Furthermore, as ball milling time changes, the maximum of both high rate discharge ability (HRD) and the gaseous hydriding rate of as-milled alloys can be obtained. But the hydrogen desorption kinetics of alloys always increases with the extending of milling time. Moreover, the improved gaseous hydrogen storage kinetics of alloys are ascribed to a decrease in the hydrogen desorption activation energy caused by increasing Ni content and milling time.

The Influence of Ni Addition on the Microstructures and Mechanical Properties of Al2O3–TiN–TiC Ceramic Materials

Al2O3–TiN–TiC ceramic materials with different Ni content were fabricated by hot-pressing technique. Mechanical properties such as flexural strength, Vickers hardness and fracture toughness were obtained by three-point-bending test and Vickers indentation method. The microstructures of the sintered body were observed by scanning electron microscopy. The effects of Ni content on the microstructures and the mechanical properties of Al2O3–TiN–TiC ceramic materials were investigated. The results indicated that the addition of Ni could change the topography of the microstructures which displayed various core–shell structures. Moreover, the fracture mode changed with the increment of Ni content. When the addition of Ni was 3 vol%, the flexural strength and fracture toughness were the greatest and the improvement could be explained by the unique microstructures of sintered bodies.

Effect of Ni content on the microstructure and mechanical properties of weld metal with both-side submerged arc welding technique

The effects of nickel (Ni) content on the mechanical properties and microstructure evolution in the weld metals of commercial K65 oil and gas pipeline steel were studied. Increase Ni content could significantly improve the strength and low temperature impact toughness (−40 °C and −60 °C) of the weld metal. The above influences of Ni were attributed to the formation of predominant acicular ferrite (AF), at the expense of grain boundary ferrite (GBF), ferrite side plates (FSP) and martensite/austenite (M/A) constituent in weld metal. EBSD results indicated that GBF keeps K-S or N-W relations only with the prior austensite grain that belongs to one side of the grain boundary and the variants belong to the same bain group which always forms low angle boundary. Moreover, the retained austenite as one part of M/A constituent was mainly found in the weld metal with lower Ni content. It indicated that the transformation process could be promoted more completely by the increase of Ni content. The mechanism of the toughness improvement brought by Ni increasing was ascribed to the relatively uniform transformation to final microstructure, which reduces the appearance of GBF and M/A constituents.

Facile One-Pot Bottom–Up Synthesis of Graphene and Ni/Graphene Nanostructures and Their Excellent Adsorption Performances

In this paper, a facile one-pot bottom-up approach for the preparation of graphene and Ni/graphene nanostructures at normal pressure and low temperature (150[Formula: see text]C) has been developed. The graphene and Ni/graphene nanostructures were prepared by reducing hexachloro-benzene (C6Cl[Formula: see text] with potassium in [Formula: see text]-tetradecane (C[Formula: see text]H[Formula: see text] solution without the presence of a catalyst. Meanwhile, the effect of Ni content on the specific surface area (SSA) of the final products was investigated. The testing results display that the as-prepared samples have large SSA and high C/O ratio, implying that the designed synthesis method is simple and efficient. To evaluate the adsorption performances of the samples, we select organic dye rhodamine B (RhB) as the model organic contaminant in aqueous solutions. The experimental results show that the samples possess high adsorption capacity ([Formula: see text][Formula: see text]mg g[Formula: see text], ultrafast adsorption rate ([Formula: see text]%, 2[Formula: see text]min), high adsorption efficiency ([Formula: see text]%) and good chemical stability in a wide pH range (2–11), high salt tolerance ([Formula: see text][Formula: see text]mg mL[Formula: see text], and good reusability ([Formula: see text]%, 9 cycles) for dye RhB from water. In particular, the samples exhibit a good property for the treatment of the raw industrial wastewater (RIW).

Ni含量对特超级双相不锈钢S32707组织与性能的影响研究

Ni含量对特超级双相不锈钢S32707组织与性能的影响研究

Effect of Ni content on stainless steel fabricated by laser melting deposition

The novel stainless steel + x wt.% Ni (x = 0, 3.05, 6.10, 9.15) specimens were successfully fabricated by laser melting deposition, aiming at investigating the influence of Ni content on stainless steel structure and property. The effects of Ni content on phase compositions, microstructure, microhardness, wear and electrochemical corrosion resistance of as-deposited stainless steel were studied systematically using XRD, OM, SEM, microhardness tester, friction-wear tester and potentiodynamic polarization measurement, respectively. Experimental results showed that with the increase of Ni content, the constituent phase of the as-deposited specimen changed from ferrite phase (specimen for x = 0) to austenite phase (specimen for x = 9.15). The microstructure growth followed the principle of dendrite growth. However, the dominant microstructure varied from equiaxed dendrite to columnar dendrite with increasing Ni content. Phase transition from ferrite phase to austenite phase with the addition of Ni content resulted in the decrease of microhardness value from 643HV to 289HV. Meanwhile, the wear resistance of as-deposited specimens decreased gradually with the increasing of Ni content, which might be attributed to the fact that the wear resistance is proportional to microhardness according to Archard's law. It was noted that corrosion resistance of as-deposited stainless steel was extremely improved with the increase of Ni content. The higher Ni content specimen (specimen for x = 9.15) exhibited the best corrosion resistance among the tested specimens based on corrosion rate, which was one order of magnitude lower than that of the lower Ni content specimens (specimens for x = 0, 3.05).

Effect of Ni-Content on the Transformation Temperatures in NiTi-20 at. % Zr High Temperature Shape Memory Alloys

The effect of Ni-content on phase transformation behavior of NiTi-20 at. % Zr high temperature shape memory alloy (HTSMA) is investigated over a small composition range, i.e., 49.8, 50.0 and 50.2 at. % Ni, by differential scanning calorimetry (DSC), high-energy synchrotron radiation X-ray diffraction (SR-XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). All samples show a monoclinic B19′ martensitic structure at room temperature. It is shown that even with these small variations in Ni-content, the alloy shows vastly different transformation temperatures and responds in a drastically different manner to aging treatments at 550 and 600 °C. Lastly, a discussion on H-phase composition with respect to bulk composition is presented.

Effect of Ni Content on Microstructure and Properties of WC-Ni Composites Prepared by Electroless Plating and Powder Metallurgy

WC-Ni composite powders were prepared by electroless plating with a simplified chemical method. The morphologies of original, pretreated WC powder, WC-Ni powders and surface morphologies, fracture surface and composition of WC-Ni composites were analyzed by FE-SEM. EDS and XRD. Different contents of Ni doped WC composites were prepared after sintering. The relative density and properties of the WC-Ni composites were also discussed. Results show that the WC powder is uniformly covered by Ni particles. After powder metallurgy (PM), the fabricated composites perform a well-dispersed surface morphology. With the increasing of Ni content bending strength enhances without reducing hardness. Trans-granular fractures are observed on the fracture surface of the WC-Ni composites.