Influence Of Ni Content Research Articles

Influence of Ni content on electrochemical corrosion and tribological behavior of Cu-10Sn coatings by laser cladding

In this work, Cu-10Sn-xNi (x = 0, 3, 6, 9, and 12 wt%) alloy coatings were prepared using laser cladding technology. The influence of Ni content on the phase composition, microstructure, crystallographic characteristics, microhardness, electrochemical corrosion, dry sliding wear and corrosive wear behavior of the coatings were studied. The results indicated that the coatings formed good metallurgical bond with the substrate. The coatings were composed primarily of the α-Cu matrix and small γ precipitates. The Ni element effectively reduced component segregation, and with the increased of Ni content, the grain size in the coating was significantly refined, resulting in fine equiaxed grains. Under the effect of fine grain strengthening, the Cu-10Sn-12Ni (C12NS) coating achieved a higher microhardness of approximately 222.9 ± 5.3 HV0.2. In the electrochemical corrosion test, the increased in the number of grain boundaries significantly reduced the corrosion resistance of the Cu-10Sn-xNi coatings. The Cu-10Sn-6Ni (C6NS) coating exhibited excellent corrosion resistance, with an Icorr of only 1.37 μA/cm2. The results of the dry sliding wear test showed that under the influence of the hardness gradient between the hard precipitate phase and the soft matrix of the coating, the C6NS coating achieved satisfactory wear resistance with a specific wear rate of 3.30 × 104 μm3/Nm. Meanwhile, due to the good corrosive resistance, the C6NS coating showed the best tribological performance in 3.5 wt% NaCl environment, and the specific wear rate was 1.58 × 104 μm3/Nm.

Influence of Ni Content on Microstructure and Hardness of Nickel-Graphite Abradable Seal Coatings Produced by Plasma Spraying

The influence of the initial shape of graphite powder and Ni content on the structure and properties of the nickel-graphite powders and plasma-sprayed coatings is investigated. The irregularly and spherically shaped graphite powders were produced by mechanical crushing and mechanical crushing with rolling, respectively. It is shown, that spherically shaped graphite powder has advantages in flowability and better deposition of Ni layer. The nickel-graphite core-shell powders with 50 and 75 wt.% Ni content were used to deposit coatings by plasma spraying. The composition, structure, and hardness of the nickel-graphite coatings were studied.

Influence of Ni on corrosion and trench formation of low alloy steel in low H2S content sour corrosion environments

AbstractThe influence of Ni content on corrosion and trench formation of low alloy steel in a low H2S containing sour corrosion environment was investigated. The results show that Ni decreases the total amount of corrosion by forming a passive film containing Ni components, such as NiS and Ni3S2 on the steel surface as a result of long‐term corrosion and suppressing the anodic dissolution reaction, while increasing the trench depth. It was also identified that the Ni content had a more dominant effect on trench formation in steel regardless of the tested sour environments with 0.01 bar H2S gas (pH 4.0) and 0.001 M Na2S2O3 (pH 2.7) in this study. Based on the experimental findings, the mechanism of trenching propagation by Ni was discussed from the viewpoint of changes in surface film properties and associated difference of corrosion resistance between trench‐tip and bulk surface due to the variation in Ni content.

Degradation in Ni-Rich LiNi1–x–yMnxCoyO2/Graphite Batteries: Impact of Charge Voltage and Ni Content

Ni-rich LiNi1–x–yMnxCoyO2 (NMC) materials are attractive as cathodes for Li-ion batteries due to their high energy density and low Co content. However, these materials may display poor electrochemical reversibility relating to structural and interfacial instabilities. The influence of Ni content and level of delithiation during charge on degradation mechanisms and relevance to electrochemical cycling behavior are probed for LiNi0.6Mn0.2Co0.2O2 (NMC622) and LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode materials in a full cell configuration under two upper voltage limits (4.1 and 4.3 V). The combined use of dQ/dV analysis of electrochemical voltage profiles, operando XRD, and postcycling scanning electron microscopy (SEM) measurements indicates that a major contributor to capacity fade is the large anisotropic volume change from an H2 ⇄ H3 phase transition and associated mechanical degradation particularly for NMC811. Notably, transition metal dissolution and deposition on the negative electrode are found to correlate with the structural changes occurring in the cathode under high voltage charge. X-ray photoelectron spectroscopy (XPS) analyses of the cycled cathodes reveal a more organic-rich cathode–electrolyte interphase (CEI) when cycling to 4.3 V with lower relative amounts of LiF. Surface reconstruction is not a significant factor under these cycling conditions as determined by soft X-ray absorption spectroscopy (sXAS) analysis. The results emphasize the opportunity to match the electrochemical test parameters with the specific NMC active material to mitigate degradation and extend cycle life.

Пластическое течение в твердых растворах Cu-Ni как автоволновой процесс

The influence of Ni content in Cu-Ni alloys on the localization of plastic flow under uniaxial tension has been studied. The regularities of localization of plastic deformation during linear and parabolic deformation hardening, as well as at the yield point, depending on the Ni content in the solid solution, have been studied by the speckle photography method. The influence of the Ni content on the duration of the stages of parabolic deformation hardening in alloys of different composition was found. The dependence of the spatial period of localization of plastic deformation (the length of the localization autowave) on the Ni content in the studied alloys is established. Keywords: localization of plastic deformation, autowaves, copper-nickel alloys, structure, mechanical properties, deformation and impurity hardening.

Plastic flow in Cu-Ni solid solutions as an autowave process

The influence of Ni content in Cu-Ni alloys on the localization of plastic flow under uniaxial tension has been studied. The regularities of localization of plastic deformation during linear and parabolic deformation hardening, as well as at the yield point, depending on the Ni content in the solid solution, have been studied by the speckle photography method. The influence of the Ni content on the duration of the stages of parabolic deformation hardening in alloys of different composition was found. The dependence of the spatial period of localization of plastic deformation (the length of the localization autowave) on the Ni content in the studied alloys is established. Keywords: localization of plastic deformation, autowaves, copper-nickel alloys, structure, mechanical properties, deformation and impurity hardening.

Influence of Ni content on the oxidation behavior of alumina-forming Co-based oxide dispersion strengthened superalloys at 900 °C

This work systematically investigated the effect of Ni additions of 10, 20 and 30 at% on the oxidation behavior of oxide dispersion-strengthened (ODS) Co-20Cr-15Al (at%) superalloys at 900 °C in air. Alumina scale with a duplex structure consisting of outer θ-alumina and inner α-alumina was formed on all tested Co-based ODS superalloys. Ni addition reduced the oxidation rate by inhibiting the growth of the outer θ-alumina during initial oxidation and the inner α-alumina during prolonged exposure. Cr2O3 formation between the interface of the θ- and α-alumina layers was confirmed with the increase of Ni content.

The Influence of Ni Content on the Microstructure and Impact Wear Resistance Performance of High-Chromium Casting Infiltration Coating

Casting infiltration technology was used to fabricate a high-chromium coating on the surface of parent ZG45 steel with different Ni content. SEM, EDS analysis, CALPHAD-type calculations, Rockwell hardness test and impact wear test were utilized to investigate the influence of Ni on the microstructure, hardness and impact wear resistance performance. The as-cast microstructure of the casting infiltration coatings with Ni content less than 2.82 wt.% was a pearlite matrix with reticular eutectic M7C3 carbide, while the matrix of the coatings with 5.53 wt.% Ni showed austenite. The content of Ni had little effect on both the solidification behavior and the amount of eutectic M7C3. After heat treatment, the transformation of the matrix to martensite occurred, and the Rockwell hardness significantly increased. The proportion of the retained austenite in the casting infiltration coatings increased from 6.4 vol.% to 27.5 vol.% with increasing Ni content, resulting in a decrease in the hardness. Due to a better balance of the hardness and toughness, the casting infiltration coating with 1.53 wt.% Ni showed the best impact wear resistance performance.

Synergistic Effect of Ni and Cu on the Microstructure, Corrosion Properties and Mechanical Properties of As-Cast Biomedical Co-Based Alloy

The microstructure, phase component, corrosion resistance, microhardness, and mechanical property of the as-cast CoCrW-(0~5)Ni-(1~4)Cu alloys were investigated to reveal the synergistic effect of Ni and Cu by using X-ray diffraction, scanning electron microscopy, electron probe microanalysis, microhardness tests, and compression tests. The alloys exhibited coarse grains consisting of dendritic substructures. No precipitate was observed in the alloys, but dendritic segregation of Cu in the interdendritic regions and grain boundaries was observed. The phase component of all alloys consists of γ phase and ε phase; the ε phase fraction decreased with increasing Ni or Cu content. The corrosion resistance of these alloys decreased with increasing Cu content when the Cu content was greater than 1 wt.%. The addition of Cu or Ni reduced the hardness significantly. The compressive yield strength showed an increasing tendency with increasing Cu content, but the influence of Ni content on compressive yield strength was limited. The results demonstrated that it should be feasible to fabricate a new biomedical CoCrWNiCu alloy by regulating Ni and Cu content, which should be a new development direction of Co-based alloy.

Structure and Wear Behavior of (Ti,Cr)C-Ni Detonation Sprayed Coatings

This study reports the influence of Ni content on the structure and wear resistance of (Ti, Cr)C-based coatings. The (Ti,Cr)C-based composite powders, cladded with 18, 25 and 33 wt.% Ni were used to deposite coatings on stainless steel substrate by detonation spraying technique. The thickness of the coatings reaches 350-500 μm, the porosity is about 2%. The (Ti,Cr)C-Ni coatings have a dense lamellar microstructure with uniform distribution of refractory particles and metal binder. The wear behavior of the coatings against steel ring were investigated by dry sliding wear tests. Depending on the Ni content the sliding wear loss of the (Ti,Cr)C-based coatings was 1,2-2 times less than that of (Ti,Cr)C detonation-sprayed coating. The investigation of worn surfaces revealed that the wear mechanism of the (Ti,Cr)C-based coatings with Ni content increase changes from abrasive to oxidative.

Effect of a constant laser energy density on the evolution of microstructure and mechanical properties of NiTi shape memory alloy fabricated by laser powder bed fusion

As the key parameter in the laser powder bed fusion (L-PBF), the laser energy density can directly determine the comprehensive quality of NiTi shape memory alloys (SMAs). However, the specific role of laser parameters under the energy density value is rarely discussed. In this work, the effect of specific laser power and scanning speed variation on the properties of NiTi alloy under the same energy density (62.5 J/mm3) was studied. Results show that the phase transformation temperatures decrease as the Ni content was increasing with the simultaneous increases in laser power and scanning speed. Under the influence of Ni content, the SMA samples with low phase transformation temperatures were fully austenite at room temperature. In the cyclic compression test at Af + 15 °C, the sample built under the lowest laser power and scanning speed showed the best superelasticity effect. Higher scanning speed resulted in a stronger <100>//BD texture, and the increase of laser power produced a deeper molten pool, which remelted the solidified part at the bottom and further enhanced the <100>//BD texture. The TEM characterization shows that more Ni4Ti3 precipitates with larger sizes are obtained in the sample with the lowest laser power and scanning speed. The finite element analysis shows the lowest peak temperature in the molten pool under the lowest laser power and scanning speed, which can promote the precipitation of Ni4Ti3 particles. The promoted formation of Ni4Ti3 precipitates enhanced the austenite stability and further enhanced the superelasticity of NiTi alloy fabricated at the lowest laser power. The present work shows that the specific laser parameter under the constant energy density value can further improve the comprehensive performance of L-PBF NiTi SMAs.

First-principles calculations to investigate elastic and thermodynamic properties of FeAlNixCrMn quinternary alloys

In this study, the structural stability, elastic properties, and thermodynamic properties of FeAlNixCrMn high-entropy alloys (HEAs) (x = 0, 0.25, 0.5, and 0.75) were systematically studied. The analysis of the total density of states and Debye temperature of FeAlNixCrMn shows that the structural stability of the alloy first increased and then decreased with the increasing of Ni content. According to the elastic constant, the influence of Ni content on the elastic modulus, toughness, brittleness, and elastic anisotropy of FeAlNixCrMn was analyzed. Finally, it is found that the thermal expansion coefficient and heat capacity show shows a strong temperature dependence only at low temperature. Furthermore, the dependence of temperature on the Grüneisen parameter is just the opposite of that of the Debye temperature. This study provides a reference and theoretical guidance for the design and performance prediction of HEAs components.

Influence of Ni Content on Microstructure and Properties of NiTi Alloy Coatings Fabricated by Laser Cladding

Influence of Ni Content on Microstructure and Properties of NiTi Alloy Coatings Fabricated by Laser Cladding

Influence of Ni content on the microstructure and reciprocating wear of Fe-based/B4C composite coating by vacuum cladding

Fe-based/B4C composite coatings without and with 1–5 wt% Ni (Ni-free and Ni-added, respectively) were fabricated on the surface of ASTM 1045 steel via vacuum cladding. The effects of Ni addition on the microstructure, hardness and reciprocating wear of Fe-based/B4C composite coatings were investigated by optical microscopy (OM), electron probe microanalysis (EPMA) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), hardness tester and reciprocating wear tester. The results showed that all coating composed of α-Fe, γ-Fe, (Fe, Ni) solid solution, M23(C, B)6, and M2B phases, which indicated that Ni addition into the coating had little impact on the composition of the M2B-type borides and M23(C, B)6-type carboborides in the coating. However, with the increase of Ni addition, the hardenability of the coating matrix was improved, and toughness phase of martensite was formed. Meanwhile, the morphology of strengthening phases gradually changed from chrysanthemum-like to intermittent net-like. When Ni addition was 3 wt%, the irregular block and net-like strengthening phases were uniformly distributed in the coating matrix of martensite, which made the microhardness of the coating relatively stable and the average hardness was 920 HV. Under different applied loads, non-significant variations in the coefficient of friction were observed. The wear volume of the coating with 3 wt% Ni addition was the minimum, which was only 2 × 10−3 mm3 under the applied load of 30 N, showing the best sliding wear performance. The wear morphology and elements distribution analysis suggested that the main wear mechanism of dry sliding wear of the coatings with different Ni addition were oxidative, adhesive and abrasive wear.

The Influence of Ni Content on the Weldability, Mechanical, and Pitting Corrosion Properties of a High-Nickel-Bearing Supermartensitic Stainless Steel

In this study, the effect of nickel content in two kinds of supermartensitic stainless steels, the new composition SMSS + Ni and already known SMSS–Ni, is compared concerning their mechanical properties as a function of tempering temperatures. The SMSS + Ni showed a microstructure composed of well-distributed thin martensite within austenite. In contrast, in the SMSS–Ni, there was much less austenite, and martensite was thicker, thus exposing it more to the environment. Therefore, one observed that the thinner the martensite, the higher the hardness and tensile stresses, and the lower the ductility. Overall, tempered samples at 620 °C presented better toughness. Therefore, the weldability of the steel SMSS + Ni was also analyzed in this tempering temperature condition, presenting excellent welding performance. However, after welding, there was an increase in austenite and thickening of martensite laths in the heat-affected zone (HAZ), leading to its poor distribution within austenite. Corrosion properties were studied comparing both kinds of steels tempered at 620 °C, which was also performed in the steel SMSS + Ni in the welded condition. It was observed that the better the distribution of martensite, the better the corrosion properties. The pitting potential for the SMSS + Ni was the lowest; its polarization curve was positioned in a nobler region, with lower corrosion potential and corrosion current density than these for the SMSS–Ni and in its welded condition.

Study on Methanation Performance of Biomass Gasification Syngas Based on a Ni/Al2O3 Monolithic Catalyst.

The structure of a Ni/Al2O3 monolithic catalyst after methanation reaction and its methanation performance were studied by taking analogue syngas of biomass gasification H2/CO/N2 as feed gas when the temperature ranged from 250 to 550 °C, and the weight hourly space velocity (WHSV) was between 6000 and 14,000 mL g–1 h–1. The Ni/Al2O3 catalysts using cordierite honeycomb ceramics as the substrate were prepared by dipping and sol–gel methods. The results show that the Ni/Al2O3 catalyst prepared by the dipping method (DIP-Ni/Al2O3) has better methanation performance than the Ni/Al2O3 catalyst prepared by the sol–gel method (SG-Ni/Al2O3) through many tests such as TEM, BET, XRD, H2-TPD, H2-TPR, and TG analysis. The DIP-Ni/Al2O3 catalyst exhibits the best methanation performance at 400 °C when the molar ratio of H2, CO, and N2 is 3/1/1 and the WHSV is 10,000 mL g–1 h–1. Under this condition, the CO conversion and CH4 selectivity are 98.6 and 90.9%, respectively. In addition, the methanation performance of the DIP-Ni/Al2O3 catalyst is relatively more stable, and the CO conversion and CH4 selectivity were basically maintained at around 90% within the experimental WHSV range. The influence of Ni content on the methanation performance of the DIP-Ni/Al2O3 catalyst can be seen in the order from high to low of methanation performance: 15% Ni, 20% Ni, and 10% Ni, and the maximum values of CO conversion and CH4 selectivity reach 96.8 and 96%, respectively, at 400 °C for 15% Ni/Al2O3.

Correlation between structure, dielectric and multiferroic properties of lead free Ni modified BaTiO3 solid solution

Present study highlights the influence of Ni doping on the structural, optical, dielectric, ferroelectric and magnetic properties of nanocrystalline BaTi1-xNixO3 (0 ≤ x ≤ 0.06) ceramics synthesized by sol-gel auto combustion process. Phase identification and crystal structure are examined through Rietveld refinement analysis that ensures mono-phase nature with tetragonal crystal structure in P4mm space group. The observed variation in the structural parameters viz. lattice constants, unit cell volume, bond lengths (Ti-O) and bond angles (Ti-O-Ti) are the direct evidence of distortion produce in the unit cell under the effect of Ni doping. The FTIR studies confirm perovskite structure and presence of stretching/bending vibrations of the various bands present in the samples. The optical properties divulge a minor alteration in optical bandgap under the influence of Ni content. Dielectric studies reveal higher value of the dielectric constant for pristine sample in the low frequency region, but its value decreases on Ni doping. The dielectric response, analyzed through UDR model, exhibits deviation from linear behavior at higher frequencies. Ferroelectric measurements demonstrate that the pristine sample has higher values of remnant polarization (Pr) and maximum polarization (Pm) which decrease linearly with the increase in Ni doping. Magnetic hysteresis loops at room temperature establish a weak ferromagnetic nature of the samples that arises due to the carrier-mediated exchange interactions with smaller values of magnetic parameters. These investigations ensure that the ferromagnetism can be induced in BaTiO3 by appropriate doping of Ni ions, which may find their potential use in the field of multiferroics.

Microstructures of nickel-doped methylated silica membrane materials calcined in air: influence of Ni content

Nickel-doped methylated silica membrane materials (Ni/CH3-SiO2) were prepared with tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as silicon precursors, and Ni(NO3)2·6H2O as Ni source by sol-gel method. The effects of Ni content on the microstructures of Ni/CH3-SiO2 membrane materials were investigated by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N2 adsorption-desorption measurements. The results indicate that the Ni element is present in the form of Ni(NO3)2·6H2O in the gel material. After firing at 350 °C in air, the Ni element mainly exists in the form of Ni-O-Si skeleton and nano-crystalline NiO. As the Ni content increased, the dispersity of NiO particles reduced and the grain size increased gradually. The methyl group is present in the Si-CH3 form in the SiO2 network. After the loading of Ni, the total pore volume decreased while the average pore size increased. The prepared 0.1Ni/CH3-SiO2 membrane material exhibited excellent microporous structure and narrow pore size distribution with the average pore size of 1.94 nm. Its microporosity reached 79.9%, which increased by 17.9% compared with the CH3-SiO2 material without Ni-loading.

Influence of Ni Content on Erosive Wear and Destabilization Heat Treatment Conditions Behavior of Multi Component White Cast Iron

This study investigated the influence of nickel (Ni) addition on erosive wear property of multi-component white cast iron with good erosive wear resistance. Multi-component white cast irons (MWCIs) with 2 mass % of carbon (C), 5 mass % of chromium (Cr), molybdenum (Mo), tungsten (W), niobium (Nb) and 0, 3, 5 mass % of Ni were prepared as experimental materials. The heat treatment condition was quenching by forced air cooling after keeping the specimens at 1123K for 3.6ks. Specimens with size of 50mm×50mm×10mm were tested using a suction-type blasting machine. The test was conducted with impact angle of 30, 60 and 90 deg. at room temperature. Collision particles were irregular steel grids with average particle diameter of 770μm and hardness of 810HV1. The speed of air flow was about 100m/s while the speed of impact particles was around 20.0g/s and the total time of each experiment was 3600 sec.. According to the result, erosion rate was decreased with the increase of Ni content in all of the impact angles. Especially, MWCIs which contain 5 mass % Ni showed the most excellent erosive wear resistance. As reasons, it can be considered that with Ni addition, the volume fraction of eutectic carbides and secondary carbides was increased which enhanced the matrix structure and suppressed the surface deformation of the experimental surface. Therefore, the increasing of eutectic carbides and secondary carbides can be considered as the reason of erosive wear resistance increased.

Influence of Nickel on High‐Temperature Oxidation and Characteristics of Oxide Layers in Two High‐Strength Steels

The oxidation behaviors of two high‐strength medium carbon steels with different Ni concentrations are investigated by means of differential thermal analysis equipped with thermogravimetry (TG). Four different oxidation temperatures and five oxidation times are tested. A parabolic behavior is observed for the oxide growth in both alloys; however, the relative increases in the oxidation rate from one temperature to another are not similar for both alloys, and the oxidation kinetics of the Ni‐rich steel are significantly lower than those of the low Ni alloy. On the basis of the TG results, the activation energy for the oxidation of the two alloys is determined. The influence of Ni content on the microstructure and characteristics of the different oxide layers is studied using a combination of laser confocal microscopy, electron microscopy, and X‐ray diffraction (XRD) analysis. The results revealed a clear influence of Ni on the nature and relative presence of different oxide layers. The results are interpreted in terms of the influence of Ni on the diffusion of oxygen through the oxide layer.