Electroless Deposition Technique Research Articles

Revolutionizing PET fabric performance with advanced metal deposition techniques

This study introduces an innovative approach to enhance both the air stability and conductivity of PET fabric using a novel dual-metal electroless deposition (ELD) technique. The fabric, woven with a combination of open weave (loose) and close weave (compact) designs, underwent coating with the metals nickel (Ni) and copper (Cu). Unlike conventional single-metal deposition methods, which often struggle to achieve optimal stability and conductivity simultaneously, this research pioneers the application of dual deposition to address these challenges effectively. The methodology entailed a series of carefully orchestrated steps including pretreatment, plasma treatment, silanization, polymerization, and ELD. The success of each stage was meticulously validated through water contact angle measurements, ensuring the efficacy of this work. Surface analysis techniques confirmed the uniform deposition of metals, as evidenced by surface morphology and elemental mapping. Additionally, detailed insights into the chemical composition and crystallinity of the coated fabrics were provided through XPS and XRD analyses. The results revealed a significant improvement in air stability and conductivity compared to traditional single-metal deposition methods. While fabrics coated solely with Cu exhibited high initial conductivity, they suffer from poor air stability. Conversely, Ni deposition demonstrated notable enhancements in air stability, with outcomes further influenced by the weave design of the fabric. Notably, in this work, the pioneering dual Ni-Cu deposition strategy not only addresses the air stability concerns associated with copper-coated fabrics but also maintains superior conductivity levels.

Influence of ultrasonic power on microstructure and performance of electroless deposited Ni-W-SiC nanocoatings

This study reports the deposition of Ni-W-SiC nanocoatings on the 45-steel using the ultrasound-assisted electroless deposition (UELD) technique. The hardness and corrosion resistance of the nanocoatings were evaluated through microhardness tests and electrochemical analyses. The surface, cross-section, phase composition, and abrasion morphologies of the coatings were studied using scanning electron microscopy and X-ray diffraction. The findings indicated that the Ni-W-SiC coating obtained at 200 W showed a compact, fine, and flat microstructure with a porosity of only 0.03 %. As the ultrasonic power during the UELD process increased from 0 W to 200 W, the SiC content in the coating rose from 2.77 to 4.16 wt% The maximum bonding force of the coating synthesized without ultrasound was approximately 89.8 N. However, the bonding force of the coatings significantly decreased with increasing ultrasonic power. The coating’s thickness also increased, from 11.09 μm at 0 W to 14.97 μm at 300 W. At 200 W ultrasonic power, the diffraction peaks of the coating were both the lowest and broadest among all the coatings. Further, the coating achieved the highest microhardness value of 676 HV. At 200 W ultrasonic power, the coating's corrosion current density was 1.63×10−7 A/cm2, which is only one-twelfth that of 45 steel, demonstrating exceptional corrosion resistance. The electrochemical impedance spectroscopy (EIS) testings indicated that an excellent corrosion resistance of Ni-W-SiC coating was deposited by using a 200 W ultrasonic power. This study provides a technical support for the preparation of nickel-based composite coatings.

Massive Onset Potential Shifting with an Epitaxial GaAs/Si Photocathode for Solar H2 Production

Solar photoelectrochemical (PEC) H2 production has the potential to solve one of the biggest issues confronting humanity nowadays: producing inexpensive, clean and renewable energy. Among various semiconductor materials, GaAs is an excellent candidate for the development of photoelectrodes within PEC cells for unassisted solar water splitting thanks to its appropriate band gap, good transport and optical properties and high quantum yield. However, the main limitations of GaAs photoelectrodes are related to the high substrate cost, their huge overpotentials and the short lifetime under operation. To address these issues, in this work, we report on the photocathode performance of 1 µm-thick GaAs layers grown on a low-cost Si p-doped substrate by MBE (Molecular Beam Epitaxy) and compare them to those of GaAs:p doped wafers . The photocathodes were investigated in 0.2 M H2SO4 (aq) electrolyte under 1 sun (100 mW/cm2) illumination. The onset potential (Vonset) of bare GaAs/Si and bare GaAs:p wafer is quite comparable, at around -0.2 V vs reversible hydrogen electrode (RHE). The significant reduction of surface states density with a sulfur passivation (S-passivation) by immersing samples in (NH4)2S solution is demonstrated but with very limited changes on the Vonset value, for both GaAs:p wafer and GaAs/Si photocathodes. In contrast, the deposition of thin Pt catalyst layers on both photocathodes by electroless deposition technique leads to a large positive shift Vonset. The Vonset of GaAs/Si and GaAs:p wafer photocathodes are increased up to 0.34 and 0.15 V vs RHE respectively. We show that the Vonset of GaAs/Si can be even improved by combining the Pt catalyst and the S-passivation process, reaching 0.4 V vs RHE (Fig. 1), a record value for GaAs-based Schottky-like photocathodes.STEM-EDX analysis was performed to investigate further the difference between Pt/GaAs/Si and Pt/GaAs:p wafer photocathodes. The EDX-line scans show that after the Pt electroless deposition, the Pt layer on GaAs:p wafer is homogeneous and shows an As0-rich Pt surface that can explain the weaker catalytic activity in comparison with GaAs/Si. Indeed, for the latter, Pt is deposited inhomogenously in the form of clusters leaving some bare surface. Here, As0 is expected to be more easily removed from the surface during the electroless deposition, resulting in more efficient catalyst properties of Pt. The morphology differences between the two Pt-coated electrodes are confirmed by XPS measurements. Since the process of electroless deposition strongly depends on the doping concentration of the materials deposited, the difference between GaAs:p wafer and GaAs/Si photocathodes is attributed to variations in their doping concentrations. Furthermore, the inhomogeneity of the Pt coating on GaAs/Si can also benefit to the passivation process by allowing the (NH4)2S solution to reduce more efficiently the surface defects at the oxide/semiconductor interface. Finally, the stability of Pt/GaAs/Si photocathodes was evaluated, and a lifetime larger than 112 h was established. These findings provide guidance for further studies towards the fabrication of scalable, cost-efficient and stable unassisted PEC cells for green hydrogen production. This research is supported by the “France 2030” French National Research Agency NAUTILUS Project (Grant no. ANR-22-PEHY-0013). Figure 1

A novel synthesis method of magnetic Janus particles for wastewater applications

HypothesisMagnetic particles are widely used in many adsorption and removal processes. Among the many types of magnetic colloids, magnetic Janus particles offer significant possibilities for the effective removal of several components from aqueous solutions. Nevertheless, the synthesis of structures integrating different types of materials requires scalable fabrication processes to overcome the limitations of the available methodologies. Herein, we hypothesized a fabrication process for dual-surface functionalized magnetic Janus particles. ExperimentsThe primary silica particles with surface-attached amine groups are further asymmetrically modified by iron oxide nanoparticles, exploiting Pickering emulsion and electroless deposition techniques. The dual surface functionality of the particles is designed for its versatility and demonstrated in two wastewater-related applications. FindingsWe show that our design can simultaneously remove chromium (VI) and phenol from aqueous solution. The fabricated magnetic-responsive Janus particles are also an effective adsorbent for genomic Deoxyribonucleic acid (DNA) and show superior performance to commercial magnetic beads. Thus, this study provides a novel platform for designing magnetic Janus particles with multifunctional surfaces for wastewater treatment applications.

Smart optical sensing of multiple antibiotic residues from wastewater effluents with ensured specificity using SERS assisted with multivariate analysis

Surface-enhanced Raman spectroscopy offers great potential for rapid and highly sensitive detection of pharmaceuticals from environmental sources. Herein, we investigated the feasibility of label-free sensing of antibiotic residues from wastewater effluents with high specificity by combining with multivariate analysis. Highly ordered silver nanoarrays with ∼34 nm roughness have been fabricated using a cost-effective electroless deposition technique. As-fabricated Ag arrays showed superior LSPR effects with an enhancement factor of 8 × 107. Excellent reproducibility has also been noticed with RSD values within 11%, whilst the sensor showed good stability and reusability characteristics for being used as a low-cost and reusable sensor. SERS studies demonstrated that antibiotics-spiked wastewater effluents can be detected with high efficiency in a label-free method. The molecular fingerprint bands of antibiotics such as sulfamethoxazole, sulfadiazine, and ciprofloxacin were well analyzed in effluent, tap, and deionized water. It has been found that antibiotics can be detected near picomolar levels; meanwhile, liquid chromatography-mass spectrometry (LC-MS) exhibited a detection limit within nanomolar concentrations only. Furthermore, the specificity of SERS sensing has been further analyzed using a multivariate analysis method, principal component analysis followed by linear discriminant analysis (PCA-LDA); which showed prominent discrimination to distinguish each antibiotic residue from wastewater effluents. The current study presented the potential of Ag nanoarray sensors for rapid, highly specific, and cost-effective analysis of pharmaceutical products for environmental remediation applications.

Effect of the Reinforcement Phase on the Electrical and Mechanical Properties of Cu-SWCNTs Nanocomposites for Potential Application on Conductors Wires

In this research a pre-treatment of single-walled carbon nanotubes (SWCNTs) was performed to obtain Cu-SWCNTs composites by combination of electroless deposition and powder metallurgy technique. Previously, the SWCNTs were subjected to a chemical functionalization in acid medium and coated with metallic copper to improve their incorporation into the metal matrix. The results revealed a suitable inclusion of carboxyl, carbonyl and hydroxyl groups in the nanotubes, maintaining their structural integrity. On the other hand, electroless process allowed a complete reduction of copper sulfate to a metallic copper and then a suitable carbon nanotubes incorporation into the matrix. Microhardness measurements presented an improvement of 13% compared with pure copper and, a good wear resistance (2.1x10-4 mm3/Nm) in the sample that reached the best hardness performance was observed. An increase of the wear rate with the concentration of nanotubes can also be seen, which could be related to the high porosity in this samples. Finally, the maximum electrical conductivity reached was 96% IACS in the samples with the least amount of SWCNTs which confirms their excellent dispersion into the copper matrix. Furthermore, the decrease of conductivity with high content of nanotubes (>0.1 weight%) could also be attributed to increase of nanocarbon agglomeration and porosity which acting as insulation barriers. Figure 1

ZnO-Doped gC3N4 Nanocapsules for Enhancing the Performance of Electroless NiP Coating-Mechanical, Corrosion Protection, and Antibacterial Properties.

A carbon nitride (C3N4) nanomaterial has superior mechanical, thermal, and tribological properties, which make them attractive for various applications, including corrosion-resistant coatings. In this research, newly synthesized C3N4 nanocapsules with different concentrations (0.5, 1.0, and 2.0 wt %) of ZnO as a dopant were incorporated into the NiP coating using an electroless deposition technique. The nanocomposite coatings either ZnO-doped (NiP-C3N4/ZnO) or undoped (NiP-C3N4) were heat-treated at 400 °C for 1 h. The as-plated and heat-treated (HT) nanocomposite coatings were characterized by their morphology, phases, roughness, wettability, hardness, corrosion protection, and antibacterial properties. The results indicated that the microhardness of as-plated and heat-treated nanocomposite coatings was significantly improved after the incorporation of 0.5 wt % ZnO-doped C3N4 nanocapsules. The outcomes of electrochemical studies revealed that the corrosion resistance of the HT coatings is higher than the corresponding as-plated ones. The highest corrosion resistance is achieved on the heat-treated NiP-C3N4/1.0 wt % ZnO coatings. Although the presence of ZnO in the C3N4 nanocapsules increased its surface area and porosity, the C3N4/ZnO nanocapsules prevented localized corrosion by filling the microdefects and pores of the NiP matrix. Furthermore, the colony-counting method used to evaluate the antibacterial behavior of the different coatings demonstrated superior antibacterial properties, namely, after heat treatment. Therefore, the novel perspective C3N4/ZnO nanocapsules can be utilized as a reinforcement nanomaterial in improving the mechanical and anticorrosion performance of NiP coatings in chloride media, together with providing superior antibacterial properties.

Synthesis of nano-SiC reinforced nickel-based nanocomposite coating using electroless deposition technique

SiC-reinforced Ni-based nanocomposite coating on aluminum alloy was prepared by an electroless deposition process. This coating technique can be used to create coatings on a variety of substrates. The majority of the literature and research on the issue focuses on the macro- and micro-scale effects of the bath composition in addition to the parameters of the process on the Ni-SiC composite coating's microstructure. Nonetheless, it has been recognized that bath composition influences on the morphology, phase structure, microstructure, and microhardness of the Ni-matrix nanocomposite coating. As a result, the current study will compare the incorporation influences of the hard ceramic SiC nanoparticles at various concentrations (0.1, 0.2, 0.4, and 0.8) g/l on the phase structure, microstructure, and microhardness of the Ni-matrix nanocomposite coating. The X-ray diffraction technique, the scanning electron microscope (SEM), and the microhardness test were used to investigate the phase structure, nanocomposite coating morphology, and microhardness, respectively.

Synthesis of bio-nanocomposite coating (silver-multi wall carbon nano tubes) by electroless plating method

Silver-multi wall carbon nanotube (Ag-MWCNTs) nano-composite coating was prepared using electroless deposition technique on stainless steel (316L) sheets. Majority of the literature and researches on this issue focuses on the macro and microscale effects of the bath composition as well as process parameters upon the composite coatings microstructure. So far, few researches have studied the bath composition influence upon the structure of phase, microstructure, and surface morphology; therefore, the current investigation compared the influences of the MWCNTs nanoparticles incorporation at various concentrations (0.1, 0.3, and 0.5 g/l) on the phase structure, microstructure and surface morphology. The phase structure changes were evaluated via X-ray Diffraction (XRD) analysis. The surface morphology (nanoparticles distribution into silver coating) was investigated via Scanning Electron Microscopy (SEM). The chemical composition of the nano-composite coating surface was studied via EDS analysis. In the present work, electroless deposition technique was used successfully in synthesis of silver-based MWCNTs nano-composite, so the EDS results showed that the main elements of the nano-composite coating are carbon, silver and oxygen that are distributed homogeneously over the surface of samples, while the SEM analysis results showed the coating is uniform and covers the stainless steel 316L substrate, also that the distribution of MWCNTs nanoparticles into the Ag matrix coating is more uniform. The XRD analysis results manifested the composition and crystal structure of the nano-composite coating consisted of Ag and MWCNTs fully crystalline structure.

Electroless Cobalt Deposition on Dealloyed Nanoporous Gold Substrate: A Versatile Technique to Control Morphological and Magnetic Properties.

The connection of multidisciplinary and versatile techniques capable of depositing and modeling thin films in multistep complex fabrication processes offers different perspectives and additional degrees of freedom in the realization of patterned magnetic materials whose peculiar physical properties meet the specific needs of several applications. In this work, a fast and cost-effective dealloying process is combined with a fast, low-cost, scalable electroless deposition technique to realize hybrid magnetic heterostructures. The gold nanoporous surface obtained by the dealloying of an Au40Si20Cu28Ag7Pd5 ribbon is used as a nanostructured substrate for the electrodeposition of cobalt. In the first steps of the deposition, the Co atoms fill the gold pores and arrange themselves into a patterned thin film with harder magnetic properties; then they continue their growth into an upper layer with softer magnetic properties. The structural characterization of the hybrid magnetic heterostructures is performed using an X-ray diffraction technique and energy-dispersive X-ray spectroscopy, while the morphology of the samples as a function of the electrodeposition time is characterized by images taken in top and cross-section view using scanning electron microscopy. Then, the structural and morphologic features are correlated with the room-temperature magnetic properties deduced from an alternating-gradient magnetometer's measurements of the hysteresis loop and first order reversal curves.

Synthesis of unsupported nanotube and flower-like nickel based structures as novel catalyst for ultra-low desulfurization of heavy gas oil at mild condition

ABSTRACT Development of heavy gas oil (HGO) desulphurisation (DS) through altering the composition of employed catalysts is crucial to enhance the quality of clean fuels production. Therefore, this research work reports an effective low-cost desulphurization performance for HGO fraction using unsupported nickel particles, of mixed compositions, having morphologies as nanotube and nanoflower-like as novel catalysts. The introduced structures were synthesised by electroless deposition technique using two reducing agents. The various characteristics of these catalysts were confirmed by XRD, TEM, BET and TGA analysis. The results of gas oil desulfurization revealed that the use of different reducing agents during the preparation stage could have an effect on the level of sulfur removal. Particularly, the produced catalyst by using methylamine, as a reducing agent, could have stronger affinity towards DS process compared to that of the obtained catalyst by hydrazine. Specifically, the catalyst of the superior DS activity could exhibit 97.5% sulfur removal from a heavy gas oil feedstock contains 10,000 ppm as sulfur content.

Polymer–assisted preparation of porous wood–based metallic composites for efficient catalytic reduction of organic pollutants

The unreasonable emission of nitroaromatic organic pollutants (NOPs) has threatened the ecological environment. However, the existing catalytic materials for NOPs reduction can not meet the actual practical application due to various functional deficiencies. In this work, novel cellulose–based metallic composites with high catalytic activity for NOPs reduction were developed through polymer–assisted electroless deposition (ELD) technique coating metallic nanoparticles onto cellulose–based porous wood surfaces. The fabricated metallic composites display outstanding catalytic ability, catalytic universality and excellent durability for most NOPs, due to the uniform catalytic metal coating enabled by polymer–assisted ELD approach and sufficient catalytic sites provided by the porous wood host surfaces. The continuous flow catalytic systems using the fabricated bulk composites were further demonstrated showing the broad prospects of such designed metallic composites in actual practical applications. This work provides a new avenue to realize rational design and large–scale fabrication of novel high–performance catalysts for NOPs reduction applications.

Iron Based Catalysts for Nitrogen Reduction Reaction

Ammonia (NH3) is a fundamental feedstock for the global population not only for its wide use as fertilizer and chemical, but also for its potential as energy storage medium. Its synthesis at the industrial scale is based on the well-known Haber Bosch process, operating at high temperature (400-500°C) and high pressure (150-300atm), thus making it highly pollutant. Considering the global climate emergency, it is mandatory to develop a green ammonia synthesis that relies on milder conditions and may adopt renewable energy sources. The electrochemical synthesis, of NH3 from N2 and H2O at ambient conditions and using renewable energy driven electricity could be a promising approach. An efficient electrochemical ammonia synthesis however, is currently still lacking. The main reasons are the absence of adequate catalysts capable of dissociating the N2 triple bond and the competition with the hydrogen evolution reaction (HER) at the cathode, since the required potential is close to that of nitrogen reduction reaction (NRR), required for the ammonia formation.There are some reaction models in the literature but it is commonly accepted that the dissociative adsorption of N2 is the rate limiting step and extensive research has been done on nitrogen interaction with metal surfaces. Ru, Co, Bi, Au, Fe, Mo, etc based materials have been extensively tested for the green ammonia synthesis, but results are still conflicting also because a complete evaluation of environmental contaminations is still lacking.In this work we adopted as NRR catalyst Fe based nanoparticles on carbon cloth substrate via a simple and fast electroless deposition technique. We prepared a FeCl3 solutions with different concentrations in the range 1-10mM and deposited a drop on (3x1.5) cm2 samples of carbon cloth, on a hot plate, at 80°C. After evaporation of the water, the as deposited substrates were dipped in NaBH4 solution while stirring.The catalyst morphology has been studied by Scanning Electron Microscopy (SEM), as a function of the concentration. Very small particles, with a size ranging from 10 to 70nm, were obtained with the most diluted solution. The cluster size increases with increasing FeCl3 concentration in the solution, giving rise to strong coalescence effects and to the formation of a thicker and continuous layer in the case of the most concentrated solution. Scanning Transmission electron Microscopy (STEM) and Electron Energy Loss Spectroscopy (EELS) have been adopted to determine the composition. EELS spectra showed that the iron L-edge is that typical of Fe3O4 materials.The electrochemical ability to reduce nitrogen, with the formation of ammonia, was evaluated in a standard two compartment cell, with a phosphate buffered solution (PBS 0.1M) adopting a Zirfon membrane as a gas separator. Ar or N2 gas (both with a purity of 99.9999%) flowed in the cathode chamber after going through an acidic trap and a water trap, to be further purified. A rigorous protocol has been adopted to evaluate the ammonia production, including a two steps measurement of the environmental ammonia at the open circuit potential. The ammonia was measured by spectrophotometric analysis using the indophenol blue method. The electrochemical production of ammonia was obtained by chronoamperometry under constant voltage.For the iron-based catalysts, a very efficient activation procedure has been developed, based on cyclic voltammetry under N2 flow. The activation process allows an improvement up to 10 times in the ammonia generation rate. Moreover, a strong correlation has been found between the particle size of the catalyst and its activity for NRR, with the best results achieved with the sample covered with nanoparticles, exhibiting also the highest electrochemical active area. Iron based nanoparticles showed excellent activity for NRR, with a faradaic efficiency of 15% at -0.35 V vs RHE and a maximum ammonia production rate of 85µg mg-1 cat h-1. Acknowledgements:This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No101006941.

Synthesis and properties of electroless Ni–P-HfC nanocomposite coatings

This work reports the development and characterization of Ni–P coatings with varying concentrations of hafnium carbide nanoparticles (HCNPs). Novel Ni–P-HCNPs nanocomposite coatings were developed on the A36 carbon steel by an electroless deposition technique. The effect of an increasing amount of HCNPs (0.25 g/L, 0.50 g/L, 0.75 g/L, and 1.00 g/L) on structural, compositional, microstructural, topographical, electrochemical and mechanical properties of Ni–P coatings was investigated. The structural (XRD, FE-SEM) and compositional analyses (EDX, XPS) confirm the successful incorporation of HCNPs into the Ni–P matrix. It is further noticed that the quantity of HCNPs has a substantial impact on modifying the microstructural, surface, mechanical, and corrosion resistance properties of Ni–P-HCNPs nanocomposite coatings. A comparative analysis of the properties of developed coatings suggests that nanocomposite coatings containing 0.75 g/L HCNPs demonstrate the highest improvement in hardness (∼40%) and corrosion resistance (∼95%) when compared to the Ni–P coatings. The increase in hardness can be attributed to the dispersion hardening effect experienced due to the presence of HCNPs. The improvement in the corrosion resistance properties can be ascribed to the reduction in the active sites of the Ni–P matrix and the filling of the micro pores with HCNPs. The attractive properties of HCNPs nanocomposite coatings provide an appealing option for their application in various industries such as aerospace, automobile, electronic, and oil & gas industry.

Layer by layer deposition of PEDOT, silver and copper to develop durable, flexible, and EMI shielding and antibacterial textiles

Nowadays due to rapid development and advancement in electronic and communication technology, human and other living beings are continually exposed to Electromagnetic Radiations. Electromagnetic shielding materials have received a great attention for hindering harmful radiations that influence the accuracy of devices and the health of living beings. In this study, flexible and conductive textile was fabricated by using different deposition techniques for the development of comfortable maternity garment to save fetus and mother from disastrous radiations. 100 % cotton with GSM 250 was opted and coatings were carried out on the surface by Poly (3,4-ethylenedioxythiophene): a conductive polymer by using dipping and drying method while conductive fillers Copper (Cu) and Silver (Ag) by electroless deposition technique. The developed fabric was investigated for elemental analysis, FTIR to find out the functional groups and XRD to discover the crystalline nature of the material whereas, Electromagnetic Interference Shielding effectiveness was inspected by using Vector Network Analyzer (VNA) ranging from 9 kHz to 13.6 GHz and had presented a good shielding effectiveness (SE) of about 45 dB. The treated fabric showed excellent antibacterial activity. The comfort properties of coated fabric were evaluated by KAWABATA evaluation system. The developed fabric is a novel shielding material for maternity garments that is low cost, light weight, durable, comfortable and could perform comprehensively.

Studying the Microstructure, Physical and Mechanical Properties of Al Matrix Reinforced with Bi-Modal Particles Coated with Either Ni or Cu

Powder metallurgy was used to fabricate Al/(SiC-Y2O3)/Ag/Cu or Ni nanocomposite. The ratio of SiC to Y2O3 was 50:50. SiC-Y2O3 particles were coated with 10 wt% nano-Ag, followed by coating with another layer of 10% nano-Ni or nano-Cu by an electroless chemical deposition technique. All samples were compacted by a uniaxial press under 480 MPa and then sintered in a vacuum furnace at 600 °C for 1 h holding time. Coated samples with nano-Cu have the highest densification values. The microstructure of nano-Cu-coated composites is more homogenous than nano-Ni ones. X-ray diffraction analysis (XRD) indicated the presence of Al peaks as a major phase, and Al3NiSi and AlCu intermetallics are detected. Also, traces of SiC and Y2O3 peaks are recorded. Hardness results showed that (SiC-Y2O3)/ nano-Ag/nano-Cu samples have higher hardness values than nano-Ni samples. Also, both the electrical and thermal conductivities are higher for nano-Cu-coated samples than for nano-Ni coated ones.

Electrochemical Behavior of Cu-MWCNT Nanocomposites Manufactured by Powder Technology

This paper presents an experimental investigation of the fabrication of Cu–multi-walled carbon nanotube (MWCNT) nanocomposites prepared via the electroless chemical deposition technique followed by the powder metallurgy (PM) method. To enhance the dispersion and wettability of MWCNTs with a Cu matrix, MWCNTs were given an electroless coating of Ag nanoparticles. MWCNTs with 0.4, 0.8, and 1.2 wt.% were first coated with 5 wt.% Ag nanoparticles, then mechanically milled with Cu nanoparticles using a 10:1 ball-to-powder ratio for 60 min at 300 rpm. The mixed samples (35 g) were subjected to a compression pressure of 700 MPa and sintered at 950 °C in a hydrogen-inert gas furnace. Mapping and microstructure analyses were conducted to analyze the constituents’ homogeneity. In addition, the electrochemical properties and corrosion resistance of specimens were investigated. The results revealed that the relative density decreased by raising the MWCNTs’ content. Electrical resistivity increased gradually with the addition of MWCNTs coated by Ag nanoparticles, and the thermal conductivity decreased. It was also revealed that the smallest corrosion rate could be obtained for the sample with 1.2 wt.% MWCNTs, which is the appropriate rate for the electrochemical deposition.

Ultrastrong, flame-retardant, intrinsically weldable, and highly conductive metallized Kevlar fabrics

Ultrastrong, flame-retardant, intrinsically weldable, and highly conductive metallized Kevlar fabrics (MKF) were fabricated via polymer-assisted electroless deposition and electrodeposition techniques.

Reducing Contact Resistance of Carbon Nanotubes by Doping of Nickel Nanoparticles

Background: In micro- and nano-electronic devices, there is often a high contact resistance between carbon nanotubes (CNTs) and metals, which leads to the heating of electronic devices and the loss of a large amount of energy. Doping will be used to improve the electrical contact performance between CNTs and metals. Significance: A simple and low-cost electroless deposition technique is used to prepare nickel-doped carbon nanotubes (CNT-Ni) under different doping conditions and explore the influence of different nickel (Ni) doped samples on the electrical contact properties of CNTs. Method: In this study, the transition metal Ni was chosen to prepare CNT-Ni by electroless deposition method using nickel chloride hexahydrate (NiCl2•6H2O) as a medium. The morphology and structure of treated CNTs were characterized through scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectrometer, and ultraviolet photoelectron spectrometer (UPS). The contact resistance between CNTs and metals was measured by inductance capacitance resistance (LCR) tester. Result: The morphological characterization results showed that the incorporated Ni nanoparticles had moderate particle size and good combination with CNTs. The structural characterization indicated that the core component of the doped nanoparticles was transition metal element Ni, and the doping type was P-type, with the significantly increased work function of the doped CNTs. And the average value of the contact resistance between the Ni-doped CNTs and the gold electrode decreased by nearly 71.63%. Conclusion: This doping method can be used to effectively reduce the contact resistance between CNTs and metals. The research on the preparation of CNT-Ni is of practical significance in reducing the heating of electronic devices in practical use and then improving the performance and service life of devices.

Fabrication of Polycrystalline Cubic Boron Nitride/Metal Composite Particles by Surface Metallization Followed by Electroless Deposition Technique.

Polycrystalline cBN/copper composite abrasive particles were prepared by an electroless powder coating process. Ti metallization and tin/silver metallization techniques were used to improve the coating process by depositing an autocatalytic metallic layer on the surface of the cBN particles. Metallized, as well as un-metallized, cBN particles were further coated by copper using electroless deposition. Electroless copper coating of un-metallized and metallized cBN particles by 90 wt.% of copper were achieved. The surface morphology, the composition and the crystalline phase identifications of the metallized cBN particles, as well as the 10 wt.% cBN /copper composite powders, were investigated by field emission scanning electron microscopy, an energy-dispersive spectrometer and an X-ray diffractometer. The results show that the surface of the Ti metalized and tin/Ag-metallized cBN particles were covered by the nanosized Ti or Ag layer, respectively, which enhanced the deposition of the copper during the electroless deposition bath. The results also showed that the deposited layer on the metallized cBN particles was composed mainly of metallic copper. The produced 10 wt.% cBN/copper composite particles also underwent thermo-gravimetric analysis to investigate its stability at high temperature. It was revealed that the Ti-metallized cBN/copper composite powder has higher stability at 800 °C under the environmental conditions than the tin/silver-metallized and the un-metallized cBN/copper composite particles, respectively.