Diffusion Of Nickel Research Articles

Влияние никеля на время жизни носителей заряда в кремниевых солнечных элементах

It has been shown experimentally that nickel clusters on the surface of a silicon sample contain a large amount of oxygen and recombination impurities - Cu, Fe, Cr, which shows good gettering properties of clusters. The optimum temperature of nickel diffusion into silicon is determined - Т=800-850 ° С. Doping with impurity nickel atoms with the formation of clusters makes it possible to increase the lifetime of nonequilibrium charge carriers in the base of a solar cell by up to 2 times, while the formation of a nickel-enriched region in the face layer is more efficient. It is shown that the effect of additional doping with nickel weakly depends on the sequence of the processes of nickel diffusion and the creation of a working p–n-junction.

The Interdiffusion Behavior of NiCoCrAlYHf Coating Deposited by Arc Ion Plating on Carburized Ni-Based Single Crystal Superalloy.

In the present study, arc ion plating (AIP) was used to prepare a NiCoCrAlYHf coating (HY5 coating) on a carburized third-generation single-crystal superalloy DD10. The interdiffusion behavior of the carburized superalloy with an HY5 coating was investigated for a 1000 h oxidation time at 1100 °C. Carburization enhanced the interfacial bonding force and improved the microstructure of the NiCoCrAlYHf coating. An interdiffusion zone (IDZ) formed after a 300 h oxidation time, and the formation of a carburized layer effectively suppressed an inward diffusion of cobalt, aluminium, and chromium to the DD10 superalloy as well as an outward diffusion of nickel and refractory elements for instance rhenium and tungsten to the HY5 coating that occurred in static air at 1100 °C. The roles of the carburized layer in affecting thermal cyclic oxidation and element interdiffusion were studied. Subsequently, a modified form of the Boltzmann–Matano analysis was used to present the interdiffusion coefficients of aluminium.

Thermophysical properties of NP2 brand nickel

The heat capacity and the thermal diffusivity of NP2 brand nickel were investigated in the temperature interval 296–1000…1375 K of the solid-state, including the region of the magnetic phase transformation. Measurements were carried out on samples from one initial ingot by laser flash technique and method of differential scanning calorimetry using LFA-427 and DSC 404 F1 setups, respectively. The thermal conductivity was calculated based on the measured thermophysical properties. The estimated errors of the obtained results were 2–4%, 3–5%, and 2–3% for thermal diffusivity, thermal conductivity, and heat capacity, respectively. For investigated thermophysical properties the fitting equations and the reference table have been received.

Electrochemical Investigation of Light-Induced Plating of Nickel on Si Solar Cells and Study of Nickel Silicide Formation

Front-contact metallization plays an important role in the fabrication of a solar cell as it adds up to 40% cost to the total production cost.1 Silver (Ag) screen printing is the commercialized technology for the front contact metallization. On the other hand, silver screen printing causes higher Si wafer breakage and results in conversion loss due to high line resistivity, poor aspect ratio and large printing spot size. Moreover, the high price of silver also drives up the cost of a solar cell. Copper, more than a hundred times cheaper than silver, is an alternate option for the front contact as its conductivity is comparable to that of silver.2 However, copper has a tendency to diffuse through Si and create recombination sites, which decreases the cell performance. To avoid diffusion of copper in silicon, a metal film has to be deposited that acts as a barrier layer. Among various diffusion barrier materials, Ni is the most promising because of its low bulk resistivity that makes nickel silicide compatible with the semiconductor technology.In this work, a nickel seed layer is deposited on silicon samples with light-induced plating (LIP) to obtain the low-resistive NiSi (1:1) phase. In-situ X-ray diffraction (XRD) is carried out along with annealing to understand the phase changes associated with silicide formation (Figure 1). The obtained XRD patterns of nickel deposited by LIP were not comparable with that of EM (electroless metal deposition). Mott-Schottky analysis is carried out to investigate the interface properties of Ni deposited by LIP and electroless methods.3, 4 XPS (X-ray photoelectron spectroscopy) data confirms the interfacial oxide which hindered the nickel diffusion to form silicide. References M. Razykov; C.S. Ferekides; D. Morel; E. Stefanakos; H.S. Ullal; H.M. Upadhyaya., Sol. Energy, 85, 1580 (2011). Kamp; J. Bartsch; S. Nold; M. Retzlaff; M. Hörteis; S.W. Glunz., Energy Procedia, 8, 558 (2011). Priyadarshani, P. Leuaa, R. Maurya, A. Kottantharayil and M. Neergat, J. Phys. Chem. C, 124, 19990 (2020).B. Bera, A. Chakraborty, T. Kar, P. Leuaa and M. Neergat, J. Phys. Chem. C, 121, 20850−20856 (2017). Figure 1

Covalently formation of insulation and barrier layers in high aspect ratio TSVs

Polymers have been widely explored as the alternative material for silicon oxide in through-silicon vias (TSVs). However, an acceptable adhesion between polymers and metallic diffusion barriers is often challenging, especially when it comes to ultrathin films with extremely low roughness. This paper proposes a cost-effective and highly reliable wet deposition path to successively fabricate polyacrylic acid (PAA) insulation films and nickel diffusion barriers on the silicon substrate. PAA films were firstly pretreated to form diazo functional groups through aryldiazonium chemistry. With an electrochemical reduction, catalytic palladium nanoparticles and palladium chelates were introduced to the pretreated substrate by robust Pd-C covalent bonds and electrostatic interaction, respectively. After being immersed into the plating solution, a continuous and uniform nickel layer on the PAA substrate with high adhesion strength can be obtained. Therefore, a stable interface between polymer insulation layers and nickel diffusion barrier can be provided by the proposed covalent fabrication approach. This wet polymer metallization approach on the flat silicon substrate was further extended in TSVs (3 μm × 30 μm) for practical deployment.

Improving the efficiency of an industrial silicon solar cell by doping with nickel

The possibility of adjusting the operational parameters of industrial solar cells produced by the company Suniva based on monocrystalline silicon by means of additional diffusion doping with nickel in the temperature range 700–1200 °C has been investigated. It is shown that the optimal temperature of nickel diffusion is Tdiff = 800–850 °C. In this case the value of the maximum power Pmax increases by 20–28 % in relation to the parameters of the original industrial photocell. At diffusion temperatures Tdiff > 1000 °C, a sharp decrease in Pmax occurs, which is associated with an increase in the depth of the p–n-junction due to the distillation of phosphorus atoms during high-temperature diffusion of nickel. The positive effect of diffusion alloying with nickel on the electrophysical parameters of photocells is greatest in the case when the nickel impurity clusters are in the region of the p–n-junction, i. e. with diffusion alloying to the front side of the plate. The action of electrically neutral nickel clusters is less pronounced when they are located in the region of the isotypic p–p+ transition; in case of diffusion alloying with nickel in the opposite side of the plate.

Investigating the Effect of Electrical Discharge Process Input Parameters on Mechanical Properties of Aluminum Surface

One of the important parameters in electrical discharge machining is the presence of micro cracks on the workpiece surface (recast layer). Therefore, the aim of this study was to investigate the possibility of increasing the mechanical properties of aluminum surface by alloying elements (copper and nickel) diffusion to the recast layer and thus removing surface micro cracks. For this purpose, pulse on time and pulse current in with and without ultrasonic vibration have been considered as input parameters and the presence of surface micro cracks has been investigated using microscopic images. Also, the yield stress of the surface layer was calculated using the surface micro hardness. Based on the obtain results, surface without micro cracks has been created on the aluminum surface due to the diffusion of copper and nickel into the workpiece surface which increased aluminum surface yield strength from 90MPa to 280MPa without ultrasonic vibrations and to 310MPa while applying ultrasonic vibrations. In other words, ultrasonic vibrations cause an average of 20% increase in surface layer yield strength. In addition, according to the wear test, in the case of using ultrasonic vibration, improving the mechanical properties of the surface has caused thinner grooves on the aluminum surface.

Влияние циклической термической обработки на структуру слоистого композиционного материала из стали марок 08кп и 08Х18Н10

The article researches the effect of five cycles of heating to a temperature of 1000 °C and two cycles of heating to a temperature of 1100 °C on the structure of a layered composite material consisted of 100 alternating layers of 08kp and 08Kh18N10 steels (one layer thickness is ~22 μm). As a result of the nickel and chromium diffusion during thermocycling, the thickness of the layers changed and an interlayer with a structure different from the structure of neighboring layers was formed. Heating to 1100 °C also has led to a partial disarrangement of the layered material structure. It was found that the real diffusion path of alloying elements during heat treatment significantly exceeds the calculated one, and chromium atoms are redistributed between the layers of the material much more actively than nickel atoms.

The Influence of Interstitial Carbon and Oxygen on Grain Boundary Diffusion in Nickel and Silver

The paper investigates the influence of interstitial carbon and oxygen atoms on their diffusion along the , and tilt grain boundaries in face-centered cubic nickel and silver. It is shown that in most cases, the impurity addition leads to the growth in the self-diffusion coefficient along the grain boundaries due to the crystal lattice distortion near the impurity atoms, thereby causing the additional lattice distortion and free volume along the grain boundaries. And the lower the initial free volume on the grain boundary, the stronger is the effect from impurities on the grain boundary diffusion. In this regard, the highest and lowest effects from the impurities are observed for the and tilt grain boundaries, respectively. It is found that the influence of interstitial carbon on the grain boundary diffusion is stronger than that of oxygen.

Microstructural and mechanical investigation of brazing 304L Stainless Steel with corner joint using a Ni-based shim and wire

This study investigated a suitable filler metal, diffusion depth of the elements of this filler metal in the base metal, and its effect on the mechanical properties of brazing bonding of sheets with different thicknesses of 304L stainless steel. For this purpose, brazing was performed with thermal induction under a vacuum of 10−5 mbar and filler metal BNi-2 at the corner structures. First, the microstructure of different joint regions including base metals, Ni affected areas, and interfaces were examined by scanning electron microscopy and then the relationships between microstructure and microhardness were compared. In sheets with different thicknesses, the differences in diffusion depth were observed. Moreover, the microhardness of different areas of the braze was revealed to be completely affected by the diffusion of nickel. Finally, it was found that, for the bonding between 304L sheets with different thicknesses, BNi-2 filler metal had reasonable strength, diffusion, and filling for vacuum applications.

Electrodeposition of Tantalum Coatings on Nitinol Stent and Composition of Intermetallic Compounds Forming During Electrolysis

The electroreduction of tantalum complexes in a chloride-fluoride melt was studied on tungsten, and nitinol electrodes. It was found that on a nitinol electrode in addition to the peak associated with the discharge of fluoride tantalum complexes, several peaks on the voltammogram related to the formation of intermetallic compounds of nickel and tantalum were observed. The electrodeposition of tantalum coatings from the NaCl-KCl-NaF(10 wt.%)-K2TaF7(10 wt.%) melt onto nitinol stent was investigated. The formation during electrolysis of several intermediate layers between the deposited layer and substrate was found and their microstructure and chemical composition were determined. It was determined that the surface layers of the nitinol are depleted in titanium due to corrosion in the melt. During electrodeposition a barrier intermetallic layer TiNi2.4Ta0.6 is formed, which prevents the penetration of tantalum into the substrate, but does not prevent the diffusion of nickel and titanium from the substrate into the deposited layer of tantalum.

Study of the degradation of a fine-grained YSZ–NiO anode material during reduction in hydrogen and reoxidation in air

In this work, the high-temperature reduction of nickel oxide and reoxidation of metallic nickel in the YSZ–NiO anode material have been studied. As-sintered material (of mode 1) manufactured by tape casting underwent two treatment modes: one-time reduction (mode 2) in pure hydrogen for 4 h at 600 °C under a pressure of 0.15 MPa; reduction/oxidation (redox) for five cycles in hydrogen/air atmospheres at 600 °C (mode 3). The material of mode 1 exhibited a bending strength of about 209 MPa. This level is high enough for anode materials. Significant changes have been detected in the microstructure of the material reduced in hydrogen (mode 2). Agglomerates of particles (average size about 5 µm) with a predominance of the zirconium phase as well as regions of small particles (1 µm) with uniformly distributed both the nickel and zirconium phases were revealed. The intergranular fracture micromechanism prevailed in the specimens tested. The material strength (40 MPa) did not satisfy the requirements for anode materials. Despite too “rigid” redox treatment mode in pure hydrogen and air at 600 °C (mode 3), the cermet is not inferior in strength (85 MPa) to those fabricated using other techniques. On the specimen fracture surface, a porous core and dense outer layers have been revealed. An increased amount of nickel in the surface layer is probably a consequence of the microstructural transformation due to the diffusion of nickel from the subsurface region towards the surface. The redox treatment caused the specimen core degradation due to forming large pores, their coalescence into cracks, and loss of material integrity. In contrast to the mixed fracture micromechanism noted in the specimen surface layer, the intergranular one in the core was revealed. The reached level of electrical conductivity and a positive effect of the treatment on the material strength indicate the potential of the tape cast material, especially, in the case of reduction in Ar–5 vol% H2 gas mixture instead of pure hydrogen.

Solute-point defect interactions, coupled diffusion, and radiation-induced segregation in fcc nickel

Radiation-induced segregation (RIS) of solutes in materials exposed to irradiation is a well-known problem. It affects the life-time of nuclear reactor core components by favouring radiation-induced degradation phenomena such as hardening and embrittlement. In this work, RIS tendencies in face-centered cubic (fcc) Ni-X (X = Cr, Fe, Ti, Mn, Si, P) dilute binary alloys are examined. The goal is to investigate the driving forces and kinetic mechanisms behind the experimentally observed segregation. By means of ab initio calculations, point-defect stabilities and interactions with solutes are determined, together with migration energies and attempt frequencies. Transport and diffusion coefficients are then calculated in a mean-field framework, to get a full picture of solute-defect kinetic coupling in the alloys. Results show that all solutes considered, with the exception of Cr, prefer vacancy-mediated over interstitial-mediated diffusion during both thermal and radiation-induced migration. Cr, on the other hand, preferentially migrates in a mixed-dumbbell configuration. P and Si are here shown to be enriched, and Fe and Mn to be depleted at sinks during irradiation of the material. Ti and Cr, on the other hand, display a crossover between enrichment at lower temperatures, and depletion in the higher temperature range. Results in this work are compared with previous studies in body-centered cubic (bcc) Fe, and discussed in the context of RIS in austenitic alloys.

Single-step metal-catalyzed synthesis of hybrid planar graphene–orbicular graphitic carbon structures using an amorphous carbon thin film as a precursor

Graphene is one of the strongest and most electrically and thermally conductive materials in nature; therefore, incorporating even traces of graphene into other materials can significantly enhance their mechanical, electrical, and thermal properties. Such graphene-based materials can be used in many applications, including flexible displays, batteries, supercapacitors, solar panels, and mobile devices. However, developing graphene-based 2D materials is challenging. In this study, a facile single-step synthesis method for fabricating thin layers of amorphous carbon (a-C) containing planar graphene (PG) and orbicular graphitic carbon (OGC) nanostructures was developed by thermal annealing in inert atmosphere using an sp3-rich a-C thin film as a precursor. By annealing thin-film stacks of Si/NiFe/a-C, a thin layer with a hybrid a-C-PG-OGC structure was produced with OGC nanostructures forming on top of PG nanostructures and pyramidal NiSix nanocrystals extending into the Si substrate due to the diffusion of nickel during elevated-temperature annealing. Raman spectroscopy and cross-sectional transmission electron microscopy confirmed the transformation from amorphous to graphitic structure in the a-C film during thermal annealing. The obtained results demonstrate that the development of this 2D material with a hybrid a-C-PG-OGC microstructure is due to a metal-catalyzed PG nucleation mechanism and a mismatch-induced OGC growth mechanism. The present method for synthesizing graphene-containing thin-film structures paves the way toward the fabrication of complex micro-assemblies where high strength and good thermoelectric properties are of paramount importance.

Изменение структуры жаростойкого алюминидо-никелевого покрытия под воздействием теплового лазерного импульса

The regularities of changes in the structure and phase composition of the thermal protective aluminide-nickel coating (Ni — 45 %; Al — 14 %; Co — 22 %; Cr — 18.9 %; Fe — 0.15 %; Nb — 0.14 %; Y — 0.09 %; Ca — 0.06 %; Mn — 0.01 %; C — 0.15 %; Si — 0.15 %; S — 0.006 %) after exposure to short-term pulsed heat fluxes of various power, created by the radiation of a pulse-periodic laser LRS-150A with a radiation wavelength λ = 1.06 µm and a pulse duration τ = 12·10–3 s. The radiation energy was E = 5, 10, and 15 J. Microstructural analysis and the elemental composition of the resulting coating were carried out as well as analysis of the phase composition. X-ray microanalysis of the coating was also carried out. In the initial state and after irradiation of the coating with a heat flux of power P = 7·103 W/cm2, light microregions are observed in the micrographs of the surface. These regions do not have clearly defined external boundaries and consist of the NiAl phase and a small amount of the Ni3Al phase with the presence of inclusions of particles containing a solid solution of Ni – Co – Cr. After irradiation of the coating with heat fluxes of higher power (P = 1.7·104 W/cm2 and P = 2.2·104 W/cm2), large convex formations appeared on its surface, consisting mainly of Ni3Al and NiAl phases. On micrographs of the surface, they appear as white areas with well-defined outer boundaries. The content of the Ni3Al phase in them in comparison with the initial state increased, and the content of the NiAl phase decreased, while the particles of inclusions of Ni, Co, and Cr disappeared. It can be assumed that an increase in the Ni3Al content is associated with the dissolution of particles of a solid solution of Ni – Co and Cr in the melt and the subsequent diffusion of nickel into the NiAl phase. When exposed to a heat flux of power P = 2.2·104 W/cm2, microcracks appear on the areas of the coating surface covered with aluminum oxide.

A numerical study on the active reaction thickness of nickel catalyst layers used in a low-pressure steam methane reforming process

With the advancement of fuel cell technologies and growing interest in the hydrogen economy, the small-scale, distributed production of hydrogen has recently been receiving considerable research attention. The steam methane reforming (SMR) process, an established industrial process for large-scale hydrogen production, can also be successfully deployed for small-scale, low-pressure hydrogen production systems, including compact reformers, microchannel reformers, plate reformers, and monolithic reformers. In this study, the active reaction thickness of nickel catalyst layers was numerically determined by solving one-dimensional reaction/diffusion problems with finite volume method. The small-scale SMR conditions were considered, such as the reforming pressure of 1–3 bar, reforming temperature of 600–800 °C, and steam-to-carbon ratio of 2–4. The results showed the active thickness for the steam reforming and reverse methanation reactions hardly exceeded 0.15 mm for 600 °C, 0.07 mm for 700 °C, and 0.05 mm for 800 °C, at the reforming pressure of 1 bar. Besides, the effects of the volume-specific nickel surface area and diffusion properties were also investigated.

An investigation on thermodynamics and kinetics of η phase formation in Nb-modified iron-nickel base A286 superalloy

In this study, precipitation of η phase (Ni3Ti) in conventional and Nb-modified (Nb-A286) A286 superalloys was evaluated at different aging times and temperatures. The TTP curve of the η phase formation was plotted using thermodynamic analyses, kinetics and microstructural studies. Depending on temperature and heat treatment, the η phase precipitated at the grain boundaries or twin sites, as a result of the γ′ phase or matrix austenite transformation. Heat treatment of conventional A286 superalloy and Nb-A286 was performed within a temperature range of 650 to 900 °C for 2 to 30 h. The η phase transformation was evaluated by scanning electron microscope (SEM) which is equipped to energy dispersive X-ray spectroscopy (EDS) and optical microscopy (OM). In the analyses based on thermodynamic calculations, the interaction of the Gibbs free energy of η phase formation and the diffusion activation energy of the elements, especially titanium and niobium, was considered. The microstructural studies showed that increasing the heat treatment time results in increasing the volume fraction of the η phase. By increasing the aging temperature to 840 and 860 °C for conventional A286 superalloy and Nb-A286 superalloy, respectively, the η phase volume fraction increased, however, further increase led to volume fraction decrease. The results of the thermodynamic analyses showed the tip of the TTP diagrams at temperatures of 860 and 820 °C for the A286 and Nb-A286 alloys, respectively. Investigation of kinetics calculations showed that η phase transformation depends on the diffusion of titanium, nickel, and niobium.

Critical indexes of the nickel thermal diffusivity

Using the laser flash method, the thermal diffusivity (a) of nickel was measured in the temperature range of 300–1680 K with a detailed study of the region near the Curie temperature Tc = 628 K. The initial experimental data in the field of magnetic phase transformation were processed by the scaling dependence, and the critical thermal diffusivity indexes (α, α’) were obtained below and above Tc : α = 0.86 and α’ = 0.26, which in absolute value significantly exceed the critical heat capacity index. The possible reasons for this difference have been briefly discussed.

Process-structure relationship in the directed energy deposition of cobalt-chromium alloy (Stellite 21) coatings

In this work, we accomplished the crack-free directed energy deposition (DED) of a multi-layer Cobalt-Chromium alloy coating (Stellite 21) on Inconel 718 substrate. Stellite alloys are used as coating materials given their resistance to wear, corrosion, and high temperature. The main challenge in DED of Stellite coatings is the proclivity for crack formation during printing. The objective of this work is to characterize the effect of the input energy density and localized laser-based preheating on the characteristics of the deposited coating, namely, crack formation, microstructural evolution, dilution of the coating composition due to diffusion of iron and nickel from the substrate, and microhardness. It is observed that cracking is alleviated on preheating the substrate and depositing the coating at a moderate energy density (~200 J·mm−3). The main finding is that cracking of DED-processed Stellite 21 coating at higher levels of energy density is linked to the elemental segregation of chromium and molybdenum, which form hard and brittle phases in the inter-dendritic regions. Cracking in the inter-dendritic regions is caused by residual stresses resulting from the steep thermal gradients at higher input energy. Localized laser-based preheating and moderate energy density mitigate steep temperature gradients and thereby avoid thermally induced cracking of the Stellite coating along the inter-dendritic regions.

Mechanism of Bi-Ni Phase Formation in a Microwave-Assisted Polyol Process.

Typically, intermetallic phases are obtained in solid‐state reactions or crystallization from melts, which are highly energy and time consuming. The polyol process takes advantage of low temperatures and short reaction times using easily obtainable starting materials. The formation mechanism of these intermetallic particles has received little attention so far, even though a deeper understanding should allow for better synthesis planning. In this study, we therefore investigated the formation of BiNi particles in ethylene glycol in a microwave‐assisted polyol process mechanistically. The coordination behavior in solution was analyzed using HPLC‐MS and UV‐Vis. Tracking the reaction with PXRD measurements, FT‐IR spectroscopy and HR‐TEM revealed a successive reduction of Bi3+ and Ni2+, leading to novel spherical core‐shell structure in a first reaction step. Bismuth particles are encased in a matrix of nickel nanoparticles of 2 nm to 6 nm in diameter and oxidation products of ethylene glycol. Step‐wise diffusion of nickel into the bismuth particle intermediately results in the bismuth‐rich compound Bi3Ni, which consecutively transforms into the BiNi phase as the reaction progresses. The impacts of the anion type, temperature and pH value were also investigated.