Silver Coatings Research Articles

Silver-coated glass fibers prepared by a simple electroless plating technique

Silver-coated glass fibers have been successfully fabricated using a simple electroless silver plating. The structures of the silver/glass fiber composites were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and scanning electron microscopy, respectively. The morphology investigation showed that the silver coatings were compact and continuous. The minimum volume resistivity could reach 4.53 × 10−4 Ω cm, suggesting excellent electric conductivity. It was found that the quality of silver deposition was influenced by dosage of ammonia solution and plating temperature. Ammonia solution served as complexing reagent and supplied an alkaline media, and higher temperature easily led to metallic oxidation. The current method is simple-handle, inexpensive, large production, and the obtained silver/glass fibers can be used as fillers to fabricate electromagnetic wave shielding materials.

Development of silver nano-coatings on silk sutures as a novel approach against surgical infections.

The infections give rise to a range of clinical problems and prolong hospitalization with increased healthcare costs. Moreover, persistent infections exasperate the problem of antibiotic resistance. The aim of this study was the development of effective and low-cost antibacterial silver coatings on surgical sutures by adopting an innovative photochemical deposition process to prevent early contamination of surgical wounds. The silver deposition technology adopted in this work is an innovative process based on the in situ photoreduction of a silver solution. The samples were dipped in the silver solution and then exposed to UV radiation in order to induce the synthesis of silver clusters on the surface of the suture. The homogeneous distribution of silver particles on the surface and on the cross-section of the treated sutures was demonstrated. All the antibacterial studies clearly demonstrated that the use of novel silver treated sutures could represent clinical advantages in terms of the prevention of surgical infections against bacterial colonization. The silver coating deposited on the sutures demonstrated no cytotoxic effect on a selected cell population. The results obtained suggested that the antibacterial silver-coated sutures developed in this work could represent an interesting alternative to conventional sutures, with evident advantages in terms of prevention of the surgical infections and on the health costs. In addiction, very low concentrations of silver significantly inhibited the microbial load, without affecting the cell viability.

Embroidered Multiband Body-Worn Antenna for GSM/PCS/WLAN Communications

A novel textile-based body-worn antenna covering the Global System for Mobile Communications/personal communications services/wireless local-area network frequency bands is presented. This antenna was made of densely embroidered metal-coated polymer fibers (e-fibers). These e-fibers are 15 $\mu$ m thick and consist of high strength, flexible polymer cores with conductive silver coatings, providing mechanical flexibility and low loss at radio frequencies. When measured in free space, the textile antenna showed comparable performance to its copper counterpart, having ${\sim}2$ dBi realized gain at all three bands. This textile antenna was simulated and measured on a full body phantom to determine the body's influence on antenna performance, including frequency detuning and pattern shadowing. The measured radiation pattern of the body-worn antenna matched well with simulation at various on-body locations for the three bands. Field measurements were also carried out by mounting the antenna onto the shoulder of a jacket, and using it to replace the one of a cell phone. We found that the communication quality using the body-worn textile antenna was equivalent to the best location of the original cell-phone antenna. Therefore, this textile-based antenna provided for a more reliable body-worn communication when mounted on the body's shoulder.

Inactivation of the antibacterial and cytotoxic properties of silver ions by biologically relevant compounds.

There has been a recent surge in the use of silver as an antimicrobial agent in a wide range of domestic and clinical products, intended to prevent or treat bacterial infections and reduce bacterial colonization of surfaces. It has been reported that the antibacterial and cytotoxic properties of silver are affected by the assay conditions, particularly the type of growth media used in vitro. The toxicity of Ag+ to bacterial cells is comparable to that of human cells. We demonstrate that biologically relevant compounds such as glutathione, cysteine and human blood components significantly reduce the toxicity of silver ions to clinically relevant pathogenic bacteria and primary human dermal fibroblasts (skin cells). Bacteria are able to grow normally in the presence of silver nitrate at >20-fold the minimum inhibitory concentration (MIC) if Ag+ and thiols are added in a 1∶1 ratio because the reaction of Ag+ with extracellular thiols prevents silver ions from interacting with cells. Extracellular thiols and human serum also significantly reduce the antimicrobial activity of silver wound dressings Aquacel-Ag (Convatec) and Acticoat (Smith & Nephew) to Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli in vitro. These results have important implications for the deployment of silver as an antimicrobial agent in environments exposed to biological tissue or secretions. Significant amounts of money and effort have been directed at the development of silver-coated medical devices (e.g. dressings, catheters, implants). We believe our findings are essential for the effective design and testing of antimicrobial silver coatings.

Silver Electrodeposition from Ionic Liquids: Coatings Morphology and Mass Transport Issues

Silver electrodeposition from [Ag][BF4] solution in [BMIM][BF4] has been investigated with the purpose of understanding the effect of the deposition conditions on the morphology of the coatings. Dense and compact silver coatings with crystalline structure have been obtained with a significant reduction of the mean grain size as a result of the increase of the current density. A discussion on the electrolyte mass transport properties and their influence in the deposition rate is also reported.

Comparative Analysis of Residual Stresses Determined by Various Methods in Brush-Plated Hard Gold and Silver Coatings

The investigated brush-plated silver and gold coatings are used for refining the surface properties of electric apparatuses. Tensile residual stresses generated in the plated coatings were determined with a thin-walled ring substrate using the curvature and instrumented indentation techniques. These stresses relax over time; the dependence of relaxation time was approximated by a linear-fractional function. The modulus of elasticity and the nanohardness of the coatings were determined by nanoindentation. The surface morphology and structure in cross-section of the coated substrates are presented.

A State-of-the-art overview

Ever-increasing demand for severe work conditions, high-performance and long-life has been drivers for developing new low-friction and wear resistant coatings and surfaces for high temperature forming tools. This paper provides an overview on the recent development of coatings and modified surfaces to minimise friction and wear between contact surfaces in high-temperature working environments. This overview covers the major progresses in: (1) nanocomposite coatings based on transition metal nitrides and oxides, and the blending with solid lubricants such as silver and (2) multi-layered coatings with different combinations of hard and/or lubricating layers and duplex systems with solid lubricants on textured hard coatings and nanotubes. The challenges and future directions towards long-life and sustainable low-friction and wear-resistant coatings and surfaces for high-temperature forming tools are discussed.

Speciation study of the heavy metals in commercially available recharge cards coatings in Nigeria and the health implication

This work assessed levels of heavy metals exposure from silver coatings of mobile phones recharge cards of three major companies (designated as A, B and C) with price denominations ▪ 100, ▪ 200 and ▪ 400 from companies A, B and C respectively, which were carefully scratched using a plastic scraper into a glass tube. The coatings were acid digested for total metal concentration, while speciation experiment for Mn, Cu, Cd and Pb was carried out. Total metals and speciation analysis were done using AAS and XRF techniques. The total metal concentration from XRF analysis was in the range: Ca (70–2140 μg/g), K (20–4930 μg/g), Sc (80–270 μg/g), Ti (1530–12,580 μg/g), Fe (50–6660 μg/g), Ni (20–2040 μg/g), Cu (20–850 μg/g) and Zn (40–460 μg/g). Cr had the lowest concentration (10 μg/g) in A (▪ 400) while Ti had the highest concentration (12,580 μg/g) in C (▪ 500) for all the coatings analyzed. AAS and XRF results agreed closely except for Fe with higher concentration. A (▪ 100) contained high concentration of the metals compared with others. Speciation study identified Mn as the most mobile element when present in the environment.

Comparison of material structures and scratch strength of thin films of glass mirrors and automobile windscreens

Several types of European and Asian automobile windscreens coated with single and multilayer fixing fluxes and silver thin films were studied, and their material structures and their scratch properties were compared with glass mirrors' by the authors. The realized laboratory tests had shown very strong influences of cracks and bubbles in the microstructures of fixing thin film layers and silver coatings on scratch resistance, acoustic emission and micro-hardness of the coatings both on glass mirrors and automobile windscreens. To examine the material structure of flux thin film layers and silver coatings scanning electron microscopy (SEM) was used. The scratch resistance, acoustic emission, nucleation and propagation of cracks were studied by an optical digital mechanical scratch tester.

Fabrication of silver nano coatings and investigation of their superhydrophobic and anticorrosion properties

Silver nano coatings were fabricated on zinc substrate by a facile method of replacement reaction. The coatings enhibit properties of superhydrophobicity and anticorrosion after being modified by dodecanethiol (DDT) and octadecanethiol (ODT). Contact angles on modified coating are 156.2° and 151.8°, respectively, and the glide angle is approximately 5°. Silver coatings superhydrophobicity is dominated by reaction time, concentration of AgNO3 and surface free energy. Finally, superhydrophobic and anticorrosion mechanisms of the coatings were analyzed and discussed.

Pressure-assisted low-temperature sintering for paper-based writing electronics

With the aim of preparing paper-based writing electronics, a kind of conductive pen was made with nano-silver ink as the conductive component and a rollerball pen as the writing implement. This was used to direct-write conductive patterns on Epson photo paper. In order to decrease the sintering temperature, pressure was introduced to enhance the driving forces for sintering. Compared with hot sintering without pressure, hot-pressure can effectively improve the conductivity of silver coatings, reduce the sintering time and thus improve productivity. Importantly, pressure can achieve a more uniform and denser microstructure, which increases the connection strength of the silver coating. At the optimum hot-pressure condition (sintering temperature 120 ° C/sintering pressure 25 MPa/sintering time 15 min), a typical measured resistivity value was 1.43 × 10−7 Ω m, nine greater than that of bulk silver. This heat treatment process is compatible with paper and does not cause any damage to the paper substrates. Even after several thousand bending cycles, the resistivity values of writing tracks by hot-pressure sintering stay almost the same (from 1.43 × 10−7 to 1.57 × 10−7 Ω m). The stability and flexibility of the writing circuits are good, which demonstrates the promising future of writing electronics.

Creating Conductive Copper–Silver Bimetallic Nanostructured Coatings Using a High Temperature Reducing Jet Aerosol Reactor

We report production of bimetallic nanostructured copper– silver coatings by in situ deposition and sintering of metal nanoparticles produced as an aerosol. The metal nanoparticles themselves have potential applications in printed electronics, catalysis, antibacterial coatings, and heat transfer fluids. In many applications, nanoparticles are dispersed in an ink, which is then printed or coated onto a substrate and converted into a nanostructured thin film. Direct deposition from the aerosol allows us to produce nanostructured thin films without first dispersing the particles in a solvent. The high temperature reducing jet process allows formation of these metal nanoparticles from low-cost metal salt precursors in the gas phase. In this method, a fuel-rich hydrogen flame provides a low-cost source of energy to drive nanoparticle formation in a reducing environment. The aqueous precursor solution is delivered into the hot combustion product gases within a converging–diverging nozzle. The high-speed gas flow atomizes the precursor and provides exceptionally rapid mixing of the precursor with the hot gases. Here, particles are formed, then immediately quenched and deposited on a glass substrate. The effect of the silver content of the mixed copper–silver films on their electrical conductivity was studied systematically, revealing an abrupt transition from low conductivity to high conductivity between 30 wt.% and 40 wt.% silver. Copyright 2013 American Association for Aerosol Research

Antibacterial silver coating on poly(ethylene terephthalate) fabric by using high power impulse magnetron sputtering

Antibacterial silver coatings on textiles, formed by various coating processes, have attracted substantial attention. However, the durability of these coatings in practice is poor, limiting their usage. The goal of this study is to prepare antibacterial silver films on poly(ethylene terephthalate) (PET) fabrics by high-power impulse magnetron sputtering (HIPIMS), which is known to provide a high plasma density, so as to form a strongly adhered film at a relatively low substrate temperature. These silver-coated textiles are expected to exhibit antibacterial efficacy and durability.The experimental results herein reveal that the silver coating can be successfully deposited on PET fabric by HIPIMS with a crystal structure presenting (111) preferred orientation and that the fibers are uniformly covered. Pre-treatment with oxygen plasma for a single minute can effectively enhance film adhesion in dry and wet rubbing tests, such that the color fastness can be ranked Grade 5 and Grade 4, respectively. The coated fabric retains the mechanical properties of its original bare fabric and the coating procedure does not induce damage to PET fabric. Antimicrobial performance testing indicates that a silver film that is deposited for more than 1min provides strong bacteriostatic (>2.0) and bactericidal (>0) effects, based on the JIS Standard. Additionally, the coated fabrics retain their antimicrobial capability after 20cycles of washing, demonstrating their long-term durability.

Argyria following the use of silver-coated megaprostheses

The aims of this study were to evaluate the incidence of local argyria in patients with silver-coated megaprostheses and to identify a possible association between argyria and elevated levels of silver both locally and in the blood. Between 2004 and 2011, 32 megaprostheses with silver coatings were implanted in 20 female and 12 male patients following revision arthroplasty for infection or resection of a malignant tumour, and the levels of silver locally in drains and seromas and in the blood were determined. The mean age of the patients was 46 years (10 to 81); one patient died in the immediate post-operative period and was excluded. Seven patients (23%) developed local argyria after a median of 25.7 months (interquartile range 2 to 44.5). Patients with and without local argyria had comparable levels of silver in the blood and aspiration fluids. The length of the implant did not influence the development of local argyria. Patients with clinical evidence of local argyria had no neurological symptoms and no evidence of renal or hepatic failure. Thus, we conclude that the short-term surveillance of blood silver levels in these patients is not required.

Microwave‐assisted synthesis of silver nanoparticles on cotton fabric modified with 3‐aminopropyltrimethoxysilane

ABSTRACTIn this study, silver nanoparticles were synthesized on cotton fabric modified with 3‐aminopropyltrimethoxysilane (APTMS) using sodium citrate as a reducing/stabilizing agent by microwave‐assisted process. The presence of a highly oriented amino‐terminated self‐assembled monolayer and formation of APTMS was demonstrated by an X‐ray photoelectron spectroscopy (XPS) analysis. The silver‐coated cotton fabrics were examined by scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX). UV protection, antistatic, and hydrophobic properties were also evaluated. The results show that silver‐coated fabric modified with APTMS possesses excellent antistatic, UV protection with ultraviolet protection factor (UPF) of 396.5 and superhydrophobic properties with contact angle of 153.2°. APTMS pretreatment improves the adhesive strength between silver coatings and cotton fabric. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3862–3868, 2013

Plasmonic gap-mode nanocavities with metallic mirrors in high-index cladding

We theoretically analyze plasmonic gap-mode nanocavities covered by a thick cladding layer at telecommunication wavelengths. In the presence of high-index cladding materials such as semiconductors, the first-order hybrid gap mode becomes more promising for lasing than the fundamental one. Still, the significant mirror loss remains the main challenge to lasing. Using silver coatings within a decent thickness range at two end facets, we show that the reflectivity is substantially enhanced above 95 %. At a coating thickness of 50 nm and cavity length of 1.51 μm, the quality factor is about 150, and the threshold gain is lower than 1500 cm(-1).

Thermo-oxidative performance of metal-coated polymers and composites

This paper presents the design, fabrication and oxidation resistance performance of metal barrier coatings on high temperature polymers and their composites. The metal thin-films are selected for their ductility, low oxygen solubility and diffusivity. The coatings are fabricated with thermal and e-beam evaporation processes. The bond between the metal topcoats and the polymeric substrates is enhanced with surface roughening and other metallic interlayers. The retardation in oxidation in coated specimens is characterized with isothermal aging studies. Experimental characterization results are presented for bismaleimide resin (BMI) and unidirectional carbon-fiber reinforced composites with aluminum, alumina, titanium, and silver coatings. Results show that the oxidation resistance is strongly related to coating durability and durable coatings substantially decelerate the oxidative degradation.

Silver‐Containing Ionic Liquids with Alkylamine Ligands

AbstractThe synthesis, structure and electrochemical properties of several silver‐containing liquid metal salts have been investigated. These ionic liquids comprise of a silver‐containing cation with a silver centre coordinated by two or more alkylamine ligands and a bis(trifluoromethylsulfonyl)imide (Tf2N) anion. With the monodentate amines tert‐butylamine (tBuAm), iso‐butylamine (iso‐BuAm), sec‐butylamine (sec‐BuAm), 2‐ethylhexylamine (2‐EtHexAm), di(2‐ethylhexyl)amine and piperidine (pip), compounds with the formula [Ag(L)2][Tf2N] are formed, several of which are room‐temperature ionic liquids and all melt at or below 100 °C. In the case of [Ag(L)2][Tf2N] (L=tBuAm, iso‐BuAm and pip), single‐crystal X‐ray diffraction shows that, in the solid state, the silver centres are two‐fold coordinated by two amine ligands and the anion and cation exist as separated ion pairs. With ethylenediamine (en), two different compounds were formed, depending on the silver‐to‐ligand ratio and their structures were elucidated by X‐ray diffraction. [Ag(en)][Tf2N] has a very high melting point and is polymeric in the solid state, with en ligands coordinated to different silver(I) centres, creating one‐dimensional chains. [Ag(en)2][Tf2N], on the other hand, is a room‐temperature ionic liquid, with four‐coordinate silver(I) centres, but is actually polymeric in the solid state. The electrodeposition behaviour of [Ag(2‐EtHexAm)2][Tf2N] and [Ag(en)2][Tf2N] was investigated both at room temperature and at 90 °C and it was possible to achieve very high current densities in unstirred solutions and to electrodeposit closed, crack‐free, silver coatings. A crystal of [Ag2(en)Cl2] was obtained from a solution of [Ag(en)][Tf2N] in deuterochloroform and its structure is described.

Obtain Quadruple Intense Plasmonic Resonances from Multilayered Gold Nanoshells by Silver Coating: Application in Multiplex Sensing

Four intense and separate localized surface plasmon resonance (LSPR) absorption peaks have been obtained in the gold-dielectric–gold–silver multilayer nanoshells. The silver coating on the gold shell results in a new LSPR peak at about 400 nm corresponding to the $$ {{\left| {\omega_{+}^{-}} \right\rangle}_{Ag }} $$ mode. The intense local electric field concentrated in the silver shell at the wavelength of 400 nm indicates that this new plasmonic band is coming from the symmetric coupling between the antibonding silver shell plasmon mode and the inner sphere plasmon. Increasing the silver shell thickness also leads to the intensity increasing of the $$ {{\left| {\omega_{+}^{-}} \right\rangle}_{Au }} $$ mode and blue shift of $$ \left| {\omega_{-}^{+}} \right\rangle $$ and $$ \left| {\omega_{-}^{-}} \right\rangle $$ modes. Therefore, quadruple intense plasmonic resonances in the visible region could be achieved in gold-dielectric–gold–silver multilayer nanoshells by tuning the geometrical parameters. And the quadruple intense plasmonic resonances in the visible region provide well potential for multiplex biosensing based on LSPR.

A significant improvement in material of foam

In investigation of different materials for electrodes used in electrolysers for hydrogen production, nickel foam shows wide interests in hydrogen scientific community. This paper brings novel results of performed experiments on pure nickel foam and nickel foam silver coated. The electrochemical behavior of chosen material in high concentrated alkaline media was studied using potentiostatic and potentiodynamic DC and AC electrochemical methods: linear polarization, electrochemical impedance spectroscopy. It was shown that using silver coatings enable higher hydrogen generation. There is defined linear region of the hydrogen production with evidence that an increasing of the electrodes overvoltage decreases the resistance to the charge transfer.