Ni-coated Carbon Nanotubes Research Articles

Vermiform Ni@CNT derived from one-pot calcination of Ni-MOF precursor for improving hydrogen storage of MgH2

The Ni-coated carbon nanotubes (Ni@CNT) composite was synthesized by the facile “filtration + calcination” of Ni-based metal−organic framework (MOF) precursor and the obtained composite was used as a catalyst for MgH2. MgH2 was mixed evenly with different amounts of Ni@CNT (2.5, 5.0 and 7.5, wt.%) through ball milling. The MgH2−5wt.%Ni@CNT can absorb 5.2 wt.% H2 at 423 K in 200 s and release about 3.75 wt.% H2 at 573 K in 1000 s. And its dehydrogenation and rehydrogenation activation energies are reduced to 87.63 and 45.28 kJ/mol (H2). The in-situ generated Mg2Ni/Mg2NiH4 exhibits a good catalytic effect due to the provided more diffusion channels that can be used as “hydrogen pump”. And the presence of carbon nanotubes improves the properties of MgH2 to some extent.

Synthesis and application of NiLa-layered double hydroxides on nickel-coated carbon nanotubes with Co-ZIF-67 composite in supercapacitors

Owing to the global climate emergency, there is considerable interest in new energy generation and storage solutions. Supercapacitors have many desirable properties of particular interest for energy storage. However, they have low energy densities, which must be improved. Materials based on zeolite imidazole skeletons (ZIFs) have uniform pores, large specific surface areas, and simple structures. Moreover, Co-ZIF-67 has high electrical conductivity, which makes it a promising candidate for energy storage applications. In this study, a Co-ZIF-67 precursor with a regular cubic structure is synthesized. This precursor is combined with Ni-coated carbon nanotubes (Ni-CNTs) and NiLa-layered double hydroxides (NiLa-LDHs). Thus, by controlling the hydrothermal reaction time, an electrode material with a nanosheet structure is applied to the CNTs. Electrochemical analysis shows that the resulting Co-ZIF-67/Ni-CNT@NiLa-LDH composite has a specific capacitance of 1710 F g−1 at a current density of 1 A g−1. The composite is combined with activated carbon (AC) to produce a Co-ZIF-67/Ni-CNT@NiLa-LDH//AC asymmetric supercapacitor, which exhibits outstanding capacitive performance (150.1 F g−1 at a current density of 1 A g−1), a wide operating voltage window (1.7 V), and outstanding stability.

Microstructure and wear properties of carbon nanotubes reinforced WE43 composite coating fabricated by laser directed energy deposition

Laser directed energy deposition (LDED) was utilized to incorporate carbon nanotubes (CNTs) into WE43 magnesium alloy, aiming to enhance its wear resistance by leveraging the exceptional mechanical and self-lubricating properties of CNTs. The LDED-prepared CNTs reinforced WE43 composite (CNTs/WE43) coatings were fabricated for evaluating the wear resistance improvement. The microstructure and wear properties of the LDED-prepared CNTs reinforced WE43 composite coating were investigated in comparison to the WE43 coating. The addition of Ni coated CNTs (Ni-CNTs) led to drastic morphologic changes including the emergence of stratified structures and distinct furrow formations. The composite coating exhibited altered segregation patterns, characterized by the presence of filamentous, punctiform, porphyritic, and ring-shaped accumulations of CNTs, Mg24Y5, and Zr cores in both the central and furrow zones. The addition of Ni-CNTs induced a decrease of up to 45.8 % in wear weight loss for the WE43 coating. The friction coefficient versus the applied loads of the WE43 and CNTs/WE43 coatings showed an opposite trend. The incorporation of CNTs significantly improved the wear resistance of the WE43 coating by enhancing its ability to resist plastic deformation, forming a protective carbon film, and providing self-lubricating effects.

Strengthening Ni-Coated CNT/Mg Composites by Optimizing the CNT Content.

The dispersion of carbon nanotubes (CNTs) is the bottleneck in CNT-reinforced metal matrix composites. In this work, CNT/Mg composites were prepared by grinding Mg powder and then dispersing CNTs via ball milling and hot pressing. The uniform distribution of Ni-coated CNTs in the matrix was achieved by optimizing the content of CNTs. Scanning electron microscope, high-resolution transmission electron microscopy and X-ray diffraction, optical microscopy, and compression tests were employed. With the CNT content being less than 1%, the CNTs can be evenly distributed in CNT/Mg composites, resulting in a sharp increase in strength. However, with the higher CNT content, the CNTs gradually cluster, leading decreased fracture strain and strength. Furthermore, the coated Ni in the CNTs reacts with the magnesium matrix and completely transforms into Mg2Ni, significantly enhancing the interface bonding. This strong interface bonding and the diffusely distributed Mg2Ni in the matrix significantly strengthen the CNT/Mg composite.

Effect of Ni-Coated Carbon Nanotubes Additions on the Eutectic Sn-0.7Cu Lead-Free Composite Solder

Sn-0.7Cu-based (all in wt.% unless specified otherwise) composite solders functionalized with Ni-coated carbon nanotubes (CNTs) with various weight proportions ranging from 0.01 to 0.2 wt.% were successfully produced. The Ni-coated CNTs were synthesized with discontinuous nickel coating by an improved electroless nickel plating technique. The microstructural, melting and wetting properties of Sn-0.7Cu-based composite solders were evaluated as a function of different amounts of Ni-coated CNTs addition. Compared to Sn-0.7Cu, it was observed that the microstructure of the composite solder added to the Ni-coated CNTs was still composed of the intermetallic compound Cu6Sn5 in a β-Sn matrix, but the micromorphology changed greatly. When 0.05 wt.% Ni-coated CNTs were added, the rod-shaped Cu6Sn5 particles disappeared, and all appeared in a form of dot-shaped Cu6Sn5 particles. DSC results showed only a slight decrease in the melting behavior of the composite solder. Experimental results unveiled that the addition of Ni-coated CNTs to Sn-0.7Cu solder could improve the wettability. With the addition of 0.05 wt.% Ni-coated CNTs, the wetting angle decreased by 13.35%, and an optimum wetting angle of 25.44° was achieved.

Effect of Ni-coated carbon nanotubes addition on the wettability, microhardness, and shear strength of Sn-3.0Ag-0.5Cu/Cu lead-free solder joints

Effect of Ni-coated carbon nanotubes addition on the wettability, microhardness, and shear strength of Sn-3.0Ag-0.5Cu/Cu lead-free solder joints

Effects of elasticity and dislocation core structure on the interaction of dislocations with embedded CNTs in aluminium: An atomistic simulation study

The interaction between edge dislocations and carbon nanotubes (CNTs) embedded into an Al matrix is investigated. Both pristine and Ni-coated CNTs are considered. It is demonstrated that the embedded CNTs lead to a yield stress contribution equivalent to that of an array of non-shearable inclusions that are by-passed via the Orowan mechanism. The strain hardening mechanism associated with multiple dislocation passes shows, however, strong effects of atomistic core structure such as crystallographic and non-crystallographic cross slip of near-screw segments on the CNT-metal interface, dislocation lock formation and annihilation, jog formation and shedding of prismatic dislocation loops.

Microstructure and shear property of Ni-coated carbon nanotubes reinforced InSn-50Ag composite solder joints prepared by transient liquid phase bonding

InSn-50Ag composite solder joints doping Ni-coated carbon nanotubes (Ni-CNTs) were fabricated by transient liquid phase (TLP) bonding, and then the effect of Ni-CNTs contents (x = 0, 0.01, 0.03, 0.05, 0.07, 0.1 wt%) on the microstructure and shear property of the composite solder joints was examined. The results showed that the microstructure of Cu/InSn-50Ag-x(Ni-CNTs)/Cu composite solder joints consisted of the interfacial region bamboo-type Cu3(In, Sn), solder center region Ag3In, Ni3Sn4, Ag particles and Ni-CNTs. The appropriate amounts of Ni-CNTs (about 0.07 wt%) are conducive to form a compact composite solder joint and restrain the growth of interfacial Cu3(In, Sn) IMC layer, and the morphologies of IMC layer are determined by Ni-CNTs suppressing atom diffusion and IMC grain orientation. The shear strength of composite solder joints relates to Ni-CNTs content, and the maximum shear strength reaches 42 MPa of Cu/InSn-50Ag-0.07(Ni-CNTs)/Cu. It is regulated by uniform distribution of Ni-CNTs, refined Ag3In grains and interface IMC layer with near-continuous voids. The fracture of the composite solder joints doped Ni-CNTs occurred near to the boundary between the interfacial IMC layer and solder center region, the fracture mechanism is ductile fracture.

Tribological Performance of Al Alloys Dispersed with Carbon Nanotubes or Ni-Coated Carbon Nanotubes Produced by Mechanical Milling and Extrusion

The microstructure, mechanical and tribological behaviors of Al alloy (AA), Al alloy-carbon nanotubes (AC) and Al alloy-Ni-coated carbon nanotubes composites (ANC) fabricated by mechanical milling of elemental powders and subsequent hot extrusion were investigated. Dry sliding wear tests conducted at three different normal loads reveal that the wear rate increases monotonously with the load. The formation and subsequent delamination of the mechanically mixed layer indicate that the general wear mechanism is a combination of sliding and adhesion, while ripple-like worn surface features correspond to wear mode transition. The higher wear resistance exhibited by AC and ANC samples correlates well with the corresponding mechanical properties achieved through the dispersion of carbon nanotubes (CNT) and Ni-coated CNT, following the traditional Archard’s wear relationship.

Optimizing the interface bonding in Cu matrix composites by using functionalized carbon nanotubes and cold rolling

Abstract

Enhancing the strength of carbon nanotubes reinforced copper matrix composites by optimizing the interface structure and dispersion uniformity

Interface between carbon nanotubes (CNTs) and copper matrix is generally weak mechanical bonding due to the lack of wetting and interaction between them. In the present study, the homogeneous distribution of CNTs in copper matrix was realized through a novel mixing method and spark plasma sintering (SPS). The interface structures of CNTs/Cu composites were optimized by using decorated CNTs. Transmission electron microscopy (TEM) observation revealed the formation of interfacial products, amorphous transition areas and interfacial stress zones at the decorated-CNT/Cu interfaces. The compressive tests showed that the composite containing 2 vol% of Ni-coated CNTs has a maximum compression yield strength of 554 MPa, which was increased by 55% and 30% compared with that of pure Cu and the composite reinforced with pristine CNTs, respectively. The strong strengthening effects of the decorated CNTs can be attributed to their interaction with Cu matrix. The strengthening mechanisms, load transfer efficiency and interfacial shear strength were also discussed from the point of interface structure. This work underscores the importance of the surface state of CNTs on the interface structure in metal matrix composites, and may provide insights into the composites where reinforcements and matrix are lack of wetting and interactions.

TC Study of Manufacturable Nano Grease: Evidence of 3D Network Structure

Surfactant-free grease made from carbon nanotube and carbon nanofibers has shown improvement in thermal conductivity. Time-dependent thermal conductivity (TC) magnetic study with different (Fe2O3 concentrations and Ni-coated carbon nanotubes) was performed. The results show that under the influence of a strong magnetic field, the TC value remains constant even with different processing times, magnetic fields, and Fe2O3 concentrations. An explanation for these results could be that for a high loading of CNTs (> 10 wt%), CNTs become associated strongly with each other by van der Waals forces and form a three-dimensional network (3D), which makes magnetic alignment of nanotubes very unlikely. A slight change on the TC of carbon nanofibers grease was noticed, which is probably because of the weak Van der Waals forces among the nanofibers. Mixing the CNFs with SWNTs produced a stable grease as SWNTs help to create the 3D network structure; however, the TC has dropped to 0.37 W/mK which is attributed to the lower TC of the SWNTs grease itself. The scientific merit of this paper is that the results provide further support that the CNTs form a 3D network structure and move forward the R&D work of manufacturable carbon nano grease.

Reliability performance of tin–bismuth–silver (Sn57.6Bi0.4Ag) solder joints with different content of carbon nano-tubes (CNTs) or nickel (Ni)-modified CNTs

In this study, the reliability performance of Sn57.6Bi0.4Ag solder joints containing different amounts (wt%) of CNTs and Ni-coated CNTs (Ni–CNTs) has been investigated. Thermal shock testing was used, as a means of harsh environmental stressing. The theory of the reinforcing effects for these two dopants was discussed. The difference of the dopant redistributing process during reflow soldering was also analysed. The formation mechanisms of cracks in the doped solder joints were elucidated through morphological analyses. Ball shear testing results were reported to substantiate the mechanical strength improvements of such joints. The characteristics of the fracture surfaces were analysed to clarify and correlate the changes in the related performance. Sn57.6Bi0.4Ag solder joints containing 0.03 wt% Ni–CNTs have been shown to offer the optimal reliability performance, as evidenced by its highest resistance to thermal shock. Ni coated ones showed a positive effect on the distribution of CNTs. However, solder joints containing excessive dopants of > 0.05 wt% yielded certain undesirable defects in the thermal shock testing, as evidenced by its deterioration in mechanical properties. The relative significance of such defects, e.g. aggregation of CNTs, formation of loose CNT-alloy structural phases and rapid propagation of cracks, varied considerably depending of the type and amount of dopants.

Preliminary demonstration of energy-efficient fabrication of aligned CNT-polymer nanocomposites using magnetic fields

Preliminary fabrication of thermoset nanocomposites with aligned carbon nanotubes (CNTs) is demonstrated using magnetic fields in an energy-efficient and quick manner. Bulk application of high-performance polymer nanocomposites is currently limited because scalable manufacturing methods to deliver bulk samples with organized nanofillers are currently missing. In this work, active assembly using external magnetic fields is selected as a solution to provide the balanced benefits of bulk processing capacity and tailorable patterning capability. Magnetically-responsive multi-walled carbon nanotubes (∼35 nm diameter and ∼200 μm length) were fabricated with relatively simple post-growth processing: low-temperature oxygen plasma treatment for improved suspension and dispersion within matrices, and e-beam coating with thin ferromagnetic nickel (Ni) layers (∼40–100 nm) for larger magnetic susceptibility. Dispersion and properties of the plasma-treated and Ni-coated CNTs were evaluated visually using the settlement study and scanning electron microscopy, and quantitatively using Raman spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometry. Assembly of Ni-coated CNTs was first demonstrated in deionized water, and then in a bisphenol-F based polymer resin (Epon 862). Magnetic assembly behaviors of these two-dimensional nanofillers were studied about the effect of their original dispersion, size, and matrix viscosity. The first sizable fabrication of CNT-thermoset nanocomposite (∼32 mm × ∼32 mm × ∼5 mm sample size) was attempted and demonstrated with the smaller magnetic field in the shorter time (∼400 G application for 40 min), than the previous attempt to assemble CNTs (∼105 G for a few hours). Future work include homogenization of CNT patterns within the nanocomposites by improving the original CNT dispersion and suspension (ferromagnetic filling instead of coating, particle surface treatment, etc.), more complex CNT patterning using magnetic field parameter modulation, and structure-interface-property studies by polymer nanocomposite characterization, specially about transport properties.

Damping characteristic of Ni-coated carbon nanotube/copper composite

In this paper, the damping capacity and mechanical strength of Ni-coated carbon nanotube (CNT) reinforced copper-matrix nanocomposites (Ni-coated CNT/CMNc) and single-crystal copper are investigated using molecular dynamics (MD). It is found that the mechanical strength of copper can be significantly improved by the embedded Ni-coated CNT. However, a relatively higher dissipation rate is observed for the Ni-coated CNT/CMNc compared with single-crystal copper. To have a better understanding of the augmented dissipation rate for Ni-coated CNT/CMNc, the effects of oscillation frequency and temperatures on the quality factor (Q factor) are explored. The simulation results show that the Q factor decreases with the increase in angular frequency or temperature for both single-crystal copper and Ni-coated CNT/CMNc. In addition, a weaker frequency and temperature dependence is obtained for the case of Ni-coated CNT/CMNc compared with single-crystal copper. Furthermore, by tracing the source of dissipated energy, we demonstrate that the distorted Cu lattice structure caused by the attraction of Ni is the dominant factor for the high damping rate of Ni-coated CNT/CMNc.

Enhanced interfacial strength of carbon nanotube/copper nanocomposites via Ni-coating: Molecular-dynamics insights

The molecular bridging between carbon nanotube (CNT) within the meta matrix is hopeful for enhancing nanocomposite's mechanical performance. One of the main problems for nanocomposites is the inadequate bonding between nonstructural reinforcement and meta matrix. Ni-coating on CNT is an effective method to overcome the drawback of the inadequate strength, but the enhancing mechanism has not well interpreted yet. In this paper, the enhancing mechanism will be interpreted from the molecular-dynamics insights. The pullout process of CNT and Ni-coated CNT against copper matrix is investigated. The effects of geometric parameters, including CNT length and diameter, are taken into considerations and discussed. Results show that the interfacial strength is significantly improved after the Ni-coated CNT, which shows a good agreement with the experimental results available in the open literature. Besides, the sliding mechanism of Ni-coated CNTs against copper matrix is much more like a kind of friction sliding and directly related to the embedded zone. However, the pullout force of the CNT without Ni-coating is nearly proportional to its diameter, but independent of embedded length.

Influence of Ni-CNTs additions on the microstructure and mechanical properties of extruded Mg-9Al alloy

Ni-coated carbon nanotubes (Ni-CNTs) reinforced Mg nanocomposites were successfully fabricated via one step ultrasound-assisted extrusion technique. The Ni-CNTs were well dispersed in both the low and high mass fraction of Mg matrices, although occasional small aggregates were observed when mass fraction of Ni-CNTs exceeded 1.5%. There are no significant variations in grain size as the introduction of Ni-CNTs. The mechanical properties of the Ni-CNTs/Mg nanocomposites with different weight percentages of Ni-CNTs (0, 0.5, 1.0, 1.5, 2.0, 3.0wt%) were discussed. The results showed that yield strength (0.2% YS), ultimate tensile strength (UTS) and hardness of Mg nanocomposites were higher than the as-extruded AZ91D alloy. The strength and ductility could be improved by Ni-CNTs addition, however, it was decreased beyond a threshold value 1.0wt%. The hardness was increased with the Ni-CNTs content. The fracture of composites was mainly caused by the pull-out and failure of Ni-CNTs. A good bonding interface without defects was observed.

Effect of Ni and Ni-coated Carbon Nanotubes on the interfacial reaction and growth behavior of Sn58Bi/Cu intermetallic compound layers

The interface reactions between Cu and Sn58Bi solder doped with mass fraction of 0.5 % Ni, 1 % Ni, 0.5 % Ni-CNTs and 1 % Ni-CNTs after reflow and solid-state aging were studied. Results show that the Ni and Ni-CNTs restrain the growth of IMC layer during reflow. After 120 and 240 h aging at 100 °C, the growth of total IMC layer and Cu3Sn layer was inhibited by the addition of Ni and Ni-CNTs. During aging, the thickness of (Cu, Ni)6Sn5 layer in Ni-CNTs-doped solder joint is always thinner than that in Ni-doped solder joint because the Ni-CNTs reduce the CTE of SnBi solder more effectively. The reason for the growth of Cu3Sn with Ni doped less than that with Ni-CNTs is that the stability of (Cu, Ni)6Sn5 gets an improvement as the Ni content increases. Besides, the IMC growth rate of composite solder joints decreases with the increasing Ni and Ni-CNTs content.

Improved microstructure and mechanical properties for Sn58Bi solder alloy by addition of Ni-coated carbon nanotubes

Ni-coated Carbon Nanotubes (Ni-CNTs) with weight percentages of 0%, 0.05%, 0.1% and 0.2% were incorporated into Sn58Bi solder alloy. The microstructure and mechanical properties of composite solders were investigated. Experimental results and finite-element simulation show that the tensile strength of solder slabs and joints is improved by the CNT bridging effect and load transfer. The fracture modes of solder joints and slabs change from ductile to brittle fracture. The creep behaviors of solders are improved significantly compared to those of the pristine samples because of the strengthening effect of Ni-CNTs. Hardness transformation is ascribed to the creep, which makes a large contribution to the plastic deformation during indentation process. Finite-element simulation indicates that the Ni3Sn4 and CNTs play the main role in the process of nanoindentation deformation. Besides, the mechanical properties and microstructure are declined when the content of Ni-CNTs exceeds 0.05%.

Effects of Ni-coated carbon nanotubes addition on the microstructure and mechanical properties of Sn–Ag–Cu solder alloys

Microstructure and mechanical properties including tensile strength as well as creep resistance of Ni-Coated Carbon Nanotube reinforced Sn–Ag–Cu solders were investigated in this study. Addition of 0.05wt% Ni-Coated Carbon Nanotubes improved the ultimate tensile strength of composite solder slabs (up to 9.80%) and joints (up to 15.95%). The increase in strengthening effect of solder joints can be attributed to the consumption of Ni by interface reaction during soldering. Nanoindentation results revealed that the creep behaviors of composite solders were improved significantly as compared to that of the unreinforced solder alloy. Finite-element modeling showed that load transfer by Carbon Nanotubes took effect but was far smaller than the effect of Ni-Coated Carbon Nanotubes served as obstacles preventing dislocations gliding.