Ni Alloy Layer Research Articles

Chemical binding and conformal coating of sub-10 nm Sn–Ni alloy layer on nanostructured carbon matrices enabling enhanced lithium storage

Alloy material is one of the most promising high-capacity anodic categories in Li-ion batteries, but suffers from huge volume expansion for practical applications. Hybridizing alloys with nanostructured carbon matrices is desirable to improve the overall electrochemical performances, however, alloys always distribute sparsely on nanostructured carbon matrices by physical connections, and easily detach from carbon matrices and aggregate to big congeries upon cycling. Here, we develop a facile and general hyrdogel-reduction approach for chemically binding and conformally coating alloys on nanostructured carbon matrices. As a typical illustration, carbon black (CB) is first immobilized within cyano-bridged Sn–Ni coordination polymer gel (Sn–Ni cyanogel), and after reduction, sub-10 nm Sn–Ni alloy layer is conformally coated on CB surface via SnOC bonds, yielding the final CB@Sn–Ni hybrid framework. The sub-10 nm alloy layer and conformal coating nanostructure together with strong chemical bonding enable the CB@"Sn–Ni hybrid anode to exhibit long cycle life (400 mA h g−1 after 350 cycles at 0.2 A g−1) and high rate performance (294 and 190 mA h g−1 at 5 and 10 A g−1, respectively). This work provides an alternative insight into conformally coating and chemical combining electrode materials with nanostructured carbon matrices for boosting electrochemical properties.

Electrodeposition of compact Ag–Ni films from concentrated chloride baths and their test in the reduction of nitrate in alkali

Compact Ag and Ag–Ni alloy layers have been electrodeposited from a concentrated chloride bath. The composition of the alloy can be controlled by regulation of the deposition current density jdep under conditions of accurate transport control like those ensured by the rotating disk electrode. XRD analyses suggest formation of Ag-rich crystalline phases in all samples and of Ni-rich crystalline phases only in samples with Ni fraction ≥50 at%. Test experiments of nitrate reduction in alkali show: almost exclusive reduction to nitrite on Ag; prevalent reduction to ammonia on Ni, with an important side evolution of hydrogen; predominant and more efficient reduction to ammonia on Ag–Ni, with lower hydrogen evolution and better current stability.

Microstructure and mechanical properties of Ti/Ta/Cu/Ni alloy laminate composite materials produced by explosive welding

Ti/Ni alloy-based laminate composite materials were produced by explosive welding with two thin intermediate layers of tantalum and copper placed between Ti and Ni alloy layers. The influence of the thickness of the Cu interlayer (0.1–0.7 mm) on the structure and mechanical properties of the explosively welded composites was examined. Investigations carried out by optical and scanning electron microscopy showed the formation of an inhomogeneous structure in the vicinity of the interfaces with zones of local melting and cavities within these zones. The wavelength and the amplitude at the interface between the copper and tantalum interlayers changed with the thickness of the copper layer. In order to evaluate the mechanical properties of the composites containing copper interlayers of different thicknesses, microhardness, tensile, and bending tests were performed. As the thickness of the copper layer was decreased to 0.3 mm, the tensile and bending strengths of the laminate composites increased.

A study of adhesive improvement of a Cr–Ni alloy layer on a polyimide surface by low pressure gas plasma modification

The influence of low pressure oxygen (O2) and argon (Ar) gas plasma modification of polyimide film on the adhesion to an alloy plating layer made from chromium (Cr) and nickel (Ni) was investigated. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed, respectively, to estimate the chemical and morphological status of the modified polyimide surface. Attenuated total reflectance-Fourier transform infrared (ATR-IR) spectroscopy and scanning electron microscopy (SEM) were also employed to determine the fracture mode during an adhesion durability test. The results indicated that O2 plasma treatments generated carboxyl groups, but an excess of carboxyl groups could oxidize the Cr at the interface at elevated temperatures, which led to a loss of adhesion.

Electrodeposition of multilayer NiMn beams for probes

A method was developed for the deposition and annealing of Ni-alloy layers to obtain a low-stress film required for high cycle wafer probe applications. Ni-alloy layers with uniform compositions from 0.145 to 0.357wt.% of Mn were electrodeposited. A high strength alloy with good ductility was produced using pulsed plating with a low internal stress level of 14MPa. In addition, a method was developed to produce a modulated composition of Mn in Ni layers from a single bath to further improve the mechanical properties of the deposits. Multilayer NiMn layers with a composition of 0.4, 0.1, and 0.6wt.% of Mn were produced. The microstructures showed mostly microcrystalline grains with shear band structures and finer grains with a lamellar structure were observed for higher Mn contents.

Microstructure and Corrosion Behavior of Ni-Alloy/CrN Nanolayered Coatings

The Ni-alloy/CrN nanolayered coatings, Ni-Al/CrN and Ni-P/CrN, were deposited on (100) silicon wafer and AISI 420 stainless steel substrates by dual-gun sputtering technique. The influences of the layer microstructure on corrosion behavior of the nanolayered thin films were investigated. The bilayer thickness was controlled approximately 10 nm with a total coating thickness of . The single-layer Ni-alloy and CrN coatings deposited at were also evaluated for comparison. Through phase identification, phases of Ni-P and Ni-Al compounds were observed in the single Ni-alloy layers. On the other hand, the nanolayered Ni-P/CrN and Ni-Al/CrN coatings showed an amorphous/nanocrystalline microstructure. The precipitation of Ni-Al and Ni-P intermetallic compounds was suppressed by the nanolayered configuration of Ni-alloy/CrN coatings. Through Tafel analysis, the and values ranged from –0.64 to –0.33 V and to A/, respectively, were deduced for various coating assemblies. The corrosion mechanisms and related behaviors of the coatings were compared. The coatings with a nanolayered Ni-alloy/CrN configuration exhibited a superior corrosion resistance to single-layer alloy or nitride coatings.

Electrical Conduction across the Direct Contact between Indium–Tin Oxide and Al–Ni Alloy Layers

The electrical conduction across direct contacts between indium–tin oxide (ITO) and the newly developed Al–Ni alloys, used for amorphous silicon thin-film transistors (a-Si TFTs) in liquid crystal displays (LCDs), has been studied. The ITO/Al–Ni alloy interfaces were examined by both electrical measurements using nanoprobes and cross-sectional transmission electron microscopy (XTEM). It was found that the major conduction path across the ITO/Al–Ni alloy interface was via Al3Ni precipitates, and that the resistivity of the ITO/Al–Ni alloy contact strongly depended on the conditions of the Al–Ni alloy surface. It was thus concluded that the generation of non-oxidized Al3Ni precipitates after photoresist stripping is important for high-quality direct contacts. The present results on the Al–Ni alloy compositions and ITO/Al–Ni alloy interfaces have already been considered in the actual production of a-Si TFTs for LCDs.

In situ spectroscopic ellipsometry study of the hydrogenation process of switchable mirrors based on magnesium-nickel alloy thin films

The hydrogenation process of switchable mirrors using magnesium-nickel alloy thin films including a thin palladium cap layer was analyzed by measuring the variation in ellipsometric angles Ψ and Δ using in situ spectroscopic ellipsometry. The process was divided into three phases and each phase was identified as follows. The first phase was the process in which the solid solution was formed because a Mg–Ni alloy in its metal state absorbs hydrogen. The second phase was the hydrogenation processes of the solid solution and the metal Pd layers. The third phase was the hydrogenation process of residual metal Pd in the Pd layer. In the initial state of the second phase, a hydride of the alloy was nucleated at the film/substrate interface as a result of hydrogenation of the solid solution, and a mixture layer of the hydride and solution was formed. With proceeding hydrogenation, the thickness of the mixture layer increased and the homogenous hydride layer was afterwards formed at the film/substrate interface. As a result of further hydrogenation, the Mg–Ni alloy layer was completely hydrogenated. After the alloy layer was completely hydrogenated, the hydrogenation of Pd was terminated.

Current Path Analysis of the Direct Contact Between ITO and Al–Ni Alloy Films

Al–Ni alloys for single-layer interconnections to be used for amorphous silicon thin-film transistors ( TFTs) in liquid-crystal displays have been developed. The developed interconnections make possible a direct electrical contact with an indium-tin oxide (ITO) film without barrier metals, such as Mo and Cr, which are conventionally used for the electrical contacts. In the present paper, we investigated the major current path at the contact between ITO film and the Al–Ni alloy layer using nanoprobes. It was found that the precipitations between the ITO film and the Al–Ni alloy layer played an important role of electrically conducting contacts. This led us to a conclusion that it is important to increase local current paths via precipitations to achieve a low resistivity at the contact between the ITO film and the Al–Ni alloy layer, which was found to be strongly influenced by the photoresist stripping process successively used for the formation of SiN contact holes in the production of TFTs.

Electroless Sn–Ni alloy plating with high Sn content free of activation pretreatment

Electroless plating technique was used to coat Sn–Ni alloy on copper substrate with high Sn content by adding the amounts of thiourea as special complexing agent and sodium hypophosphite as reducing agent to an acidic electroless plating bath of SnCl 2 and NiCl 2, which avoided activation pretreatment in plating process. The Sn content of the Sn–Ni layer increased with lowing temperature which reached 60 wt.% under optimum plating conditions. The effect of thiourea and sodium hypophosphite amount, plating temperature, and the acidity of plating bath was also discussed in this article. The corrosion-resistance properties of Sn–Ni alloy layer proved to be good by testing the anodic polarization curves of the alloy layer.

Formation and characterization of Ni alloy layer by using the Micro Spark Coating

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Toward Solid-State Switchable Mirror Devices Using Magnesium-Rich Magnesium–Nickel Alloy Thin Films

All-solid-state devices with switchable mirror properties based on magnesium-rich magnesium–nickel alloy thin films have been prepared using magnetron sputtering. The structure of the devices was a Mg–Ni alloy (40 nm)/Pd (4 nm)/Ta2O5 (200 nm)/HxWO3 (500 nm)/ITO on a glass. The composition of the alloy was Mg5Ni. In the initial state, the devices showed a shiny metallic front side and a deep blue back side, namely, in a reflective state. The optical transmittance of the devices at a wavelength of 670 nm was modulated between ∼0.3% (the reflective state) and ∼40% (the transparent state) by applying a voltage of ±5 V between the ITO and the Mg–Ni alloy layer. The color of the portion changed to the transparent state was relatively neutral. The transition from the reflective state to the transparent state started from the fringe of the electric contact on the Mg–Ni alloy side, and the transparent region spread gradually.

Joint strength and interfacial microstructure in silicon nitride/nickel-based Inconel 718 alloy bonding

Joining of Inconel 718 alloys to silicon nitrides using Ag–27Cu–3Ti alloys was performed to investigate the microstructural features of interfacial phases and their effect on joint strength. The Si3N4/Inconel 718 alloy joints had a low shear strength in the range 70.4–46.1 MPa on average, depending on joining temperature and time. When the joining time was held for 1.26 ks at 1063 K, shear, tension, and four-point bending strength were 70.4, 129.7, and 326.5 MPa on average. The microstructures of the joints typically consisted of six types of phases. They were TiN and Ti5Si4 between silicon nitride and filler metal, a copper- and silver-rich phase, island-shaped Ti–Cu phase, a Ti–Cu–Ni alloy layer between filler and base metal, and diffusion of titanium into the Inconel 718 alloys. With increasing joining temperature, the thickness increase of the Ti–Cu–Ni alloy layer was much greater than that of the reaction layer. Thus the diffusion rate of titanium into the base metal was much greater than the reaction rate with silicon nitride. This behaviour of titanium results in the formation of a Ti–Cu–Ni alloy layer in all the joints. The formation of these layers was the cause of the strength degradation of the Si3N4/Inconel 718 alloy joints. This fact was supported by the analyses of fracture path after four-point bending strength tests.

Residual stress distribution in electroplated Zn—Ni alloy layer determined by X-ray diffraction

The residual stress of electroplated Zn—Ni alloy was analyzed using a new X-ray diffraction technique developed by the authors. The distribution of residual stress in the thickness direction can be obtained non-destructively using the present method. The principles of the method are explained and measurement of the stress of electroplated Zn—Ni alloy is described. The thickness of the plating examined was between 2 and 10 μm. Non-linear sin2ø diagrams were obtained from all specimens, which suggested the existence of a steep stress gradient in the thickness direction. Microscope observation of cross-sections showed that there were cracks in the plating at areas where tensile stresses occured.

Study of Ni as a barrier metal in AuSn soldering application for laser chip/submount assembly

The possibility of replacing Pt in the Ti/Pt/Au base and traditionally used metallurgical structure by Ni, while bonding InP laser chip to a submount with AuSn (80% Au) solder, has been investigated. Various Ni-based metal alloys have been prepared by evaporation. Reflow experiments were conducted in a chamber under forming gas-controlled ambient. The Ti/Ni/AuSn system provided much longer surface local freezing duration compared to the Ti/Pt/AuSn system. Scanning electron microscopy analysis revealed a smoother surface morphology for the Ti/Ni/AuSn system after the metal refroze. Auger electron spectroscopy depth profiles indicated the formation of a Ni-Sn-Au interacted layer. The interaction took place in two steps: the first stage was the dissolution of Ni into the Au-Sn liquid followed by precipitation of a Ni-Sn-Au intermetallic compound; the second stage was a solid-state interdiffusion of Sn, Au, and Ni which occured in the interacted layer and in the original Ni layer. The latter step was a diffusion-controlled process, resulting in a very slow growth rate. Both Au and Sn reacted to form Ni alloy layers of almost equal thickness, regardless of the reaction duration (up to about 5 min). This intensive reaction, however, did not lead to full consumption of the Ti interfacial layer, which provided an excellent adhesion layer between the submount and the metallurgical structure.