Optimal Electrodeposition Research Articles

Identification of the most significant electrode positions in electromyographic evaluation of swallowing-related movements in humans

Surface electromyography (sEMG) is a well-established procedure for recording swallowing-related muscle activities. Because the use of a large number of sEMG channels is time consuming and technically sophisticated, the aim of this study was to identify the most significant electrode positions associated with oropharyngeal swallowing activities. Healthy subjects (N=16) were tested with a total of 42 channels placed in M. masseter, M. orbicularis oris, submental and paralaryngeal regions. Each test subject swallowed 10ml of water five times. After having identified 16 optimal electrode positions, that is, positions with the strongest signals quantified by the highest integral values, differences to 26 other ones were determined by a Mann-Whitney U test. Kruskal-Wallis H test was utilized for the analysis of differences between single subjects, subject subgroups, and single electrode positions. Factors associated with sEMG signals were examined in a linear regression. Sixteen electrode positions were chosen by a simple ranking of integral values. These positions delivered significantly higher signals than the other 26 positions. Differences between single electrode positions and between test subjects were also significant. Sixteen most significant positions were identified which represent swallowing-related muscle potentials in healthy subjects.

Corrosion performance of superhydrophobic nickel stearate/nickel hydroxide thin films on aluminum alloy by a simple one-step electrodeposition process

Superhydrophobic thin films are fabricated on chemically cleaned aluminum alloy substrates by a one-step electrodeposition process in the ethanolic solution containing Ni2 + ions and stearic acid (SA) under applied DC voltage. Morphological features observed by scanning electron microscopy (SEM), indicate that the thin films are composed of cauliflower-like structures with micro-nano scale particles. The chemical compositions of these films are characterized using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), which indicate that these films consist of low energy nickel stearate (Ni(SA)2). A schematic model of the electrodeposition process of Ni(SA)2 is also presented. Wetting analysis demonstrates that the surface of the film is superhydrophobic with a water contact angle (CA) of 160 ± 1° with contact angle hysteresis (CAH) of 2.1 ± 1°, which is obtained under optimum electrodeposition conditions based on a 0.4 molar ratio of Ni2 +/SA solution. The corrosion resistance properties calculated from the Tafel curve of superhydrophobic surfaces prepared in this solution are 280 times larger than the chemically cleaned aluminum alloy substrate. Furthermore, electrochemical impedance spectroscopy (EIS) analysis demonstrates that the charge transfer resistance is 1.63 × 107 Ω·cm2 for superhydrophobic films (Ni2 +/SA = 0.4) compared to that of chemically cleaned aluminum alloy substrates (1.56 × 103 Ω·cm2). Therefore, the superhydrophobic film of Ni(SA)2 on the chemically cleaned aluminum alloy substrate improves the corrosion resistance performance of aluminum substrates in corrosive environments.

Enhanced performance of an air-assisted electrostatic nozzle: Role of electrode material and its dimensional considerations in spray charging

The development of reliable means of charging for finely divided particulate matter is among the major portion of the research activities in electrostatic spraying. This paper presents the role of electrode material and engineering aspects in spray charging with emphasis on theoretical considerations of selection of electrode material and its dimensional shape and size. It reveals the charge-to-mass ratio dependency on variables such as electrode material, shape and geometrical specifications, which is in good agreement with the theoretical considerations. For the particular designed electrostatic nozzle, it is found that optimum electrode position is in the range of 2.0–3.0 mm from the nozzle tip. The copper electroplated with nickel as a charging electrode material can be plausible alternative for spray charging as excellent charge-to-mass ratio 2.8 mC/kg is attained for improved efficacy and efficiency of the electrostatic spraying processes. Possible limitations requiring further research includes the design for maximum charge injection rate, which is thought to be limited by corona breakdown, again a trade-off in air media between charging electrode and liquid sheet.

Electrodeposition of Dendritic Ni-Co Onto High-Voltage Electrodes of Electrostatic Particulate Matter (PM) Sensors

Particulate matter (PM) or soot sensing technologies are needed for feedback and control of exhaust after-treatment systems to meet increasingly stringent environmental regulations. A novel low-cost electrostatic PM sensing approach has recently been developed based on a concentric electrode design with a central cylindrical high-voltage electrode surrounded by an inner baffle that serves as the ground/negative terminal. The sensing principle is not completely understood, but seems to rely on capturing naturally combustion charged particles on electrode surfaces where a delay in sensor startup time occurs during initial testing. The influence of three-dimensional dendritic Ni-Co coatings on PM sensor performance was examined. Nickel and cobalt were co-electrodeposited on cylindrical stainless steel substrates from an electrolytic bath using a square waveform cathodic current. The effect of altering the applied current density and the number of current cycles on the height and spacing of dendritic features was monitored in attempts to correlate surface morphology to the performance of the materials as PM sensors. Coatings were characterized using scanning electron microscopy and confocal laser microscopy, and Ni-Co coated cylinders were used as the central high-voltage electrodes of electrostatic PM sensors to determine the effect of different microstructures on sensor performance. The coated electrodes demonstrated an improvement in startup time for an optimized coating morphology when compared to bare control electrodes. The surface features of the dendritic Ni-Co coatings are believed to alter the interaction of PM with the high-voltage electrode and can induce a faster response of the sensor when optimal electrodeposition conditions are employed.

ID 97 – Correlations between intraoperative microelectrode recording, microstimulation and macrostimulation with optimal post-operative programming of deep brain stimulation

Introduction Microelectrode recording (MER) is a means of analyzing the electrical activity of the brain, and assessing whether we have found the target for the deep brain stimulator (DBS) electrode. However, no evidence exists that microelectrode recording improves patient outcomes. DBS electrical pulses should activate the intended target structure alone without spreading electrical current to adjacent neural structures which would result in adverse effects being recorded. Intraoperative microstimulation (mSTIM) can test this aspect quite precisely but it is not always performed. Objective Asses the influence of MER and mSTIM over optimal post-operative programming of DBS. Material and methods Prospective transversal study of 15 patients with Parkinson disease who underwent a MRI navigated DBS surgery of bilateral STN, with MER, mSTIM and macrostimulation (MSTIM). Results The overall outcome in these patients was satisfactory after an optimal DBS programming was established. The chosen optimal position of electrodes was correlated with MER results and type of stimulation (monopolar/bipolar) or intensity was guided by mSTIM. MSTIM was only able to predict adverse effects that would be encountered with high intensities. Discussion Through the use of intraoperative MER, with mSTIM, neurologist can assure for optimal post-operative programming of the DBS.

Electrodeposition of Ordered Copper Germanide from an Alkaline Tartrate-Complexed Electrolyte

Copper is widely used for contacts and interconnects in Si-based semiconductor devices. Copper, however, is regarded as the fastest interstitial-diffusing element in Si with a diffusivity of ~ 10-8 cm2/s at room temperature [[i]]. The diffusion of copper into surrounding materials would significantly degrade their properties and the performance of semiconductor devices. Therefore, a barrier metal layer is necessarily required to completely surround all copper interconnects, which complicates the device fabrication. Recently, copper germanide (ɛ-Cu3Ge) has received much attention as a promising candidate material for contacts and interconnects due to its remarkably low resistivity of 5.5 μΩ cm at 300K [[ii]], which is only approximately three times the resistivity of pure Cu films. In particular, Cu3Ge is stable up to a temperature of 450°C, thus impeding the diffusion of Cu from the film into the surrounding materials, making it an excellent candidate for interconnects in Si-based devices [[iii]]. In the present work, the electrochemical deposition of ɛ-Cu3Ge thin films from an alkaline tartrate-complexed electrolyte [[iv]] was thoroughly investigated. Primarily, the partial (single element Cu and Ge deposition) and net (Cu-Ge alloy co-deposition) processes occurring in such electrolyte were studied by means of cyclic voltammetry (CV), electrochemical quartz crystal microbalance (EQCM) and electrochemical impedance spectroscopy (EIS) techniques. Subsequently, the electrodeposition of Cu-Ge thin films was realized in potentiostatic mode at various selected potentials. The morphology, composition and microstructure of as-deposited Cu-Ge thin films were characterized, and the results reveal that the Ge content in the deposits increases with decreasing applied potential in a sigmoidal manner, leading to a gradual disorder-order phase transformation of Cu-Ge alloy from a disordered face-centered-cubic solid solution (α-phase) to an ordered orthorhombic Cu3Ge intermetallic compound (ɛ-phase). Combining the morphological, compositional and structural characteristics of electrodeposited Cu-Ge thin films with the processes kinetics studies, a possible mechanism of Cu-Ge induced codeposition was postulated. The dependence of resistivity of as-deposited Cu-Ge thin films on Ge content was also examined, which exhibits a non-monotonic behavior. A minimum value was found around stoichiometric Cu3Ge, which corresponds to the completion of the disorder-order transformation. The ɛ-Cu3Ge thin film displays a resistivity of 7.5 μΩ cm-1 (~50 nm) and 25 μΩ cm-1 (~1 μm), increasing with the deposition duration, which is believed due to the progressive incorporation of O into the films. In order to overcome this limitation, the effect of the bath temperature and pH on Cu-Ge electrodeposition kinetics, composition and microstructure were investigated, and optimal electrodeposition conditions for ɛ-Cu3Ge were identified. [i] M.O. Aboelfotoh, H.M. Tawancy, L. Krusin-Elbaum, Correlation of electrical-resistivity anomalies and crystal structure in copper-germanium thin-film alloys, Appl. Phys. Lett. 63, 1622 (1993). [ii] L. Krunsin-Elbaum, M.O. Aboelfotoh, Unusually low resistivity of copper germanide thin films formed at low temperatures, Appl. Phys. Lett. 58, 1341 (1991). [iii] M.A. Borek, S. Oktyabrsky, M.O. Aboelfotoh, J. Narayan, Low resistivity copper germanide on (100) Si for contacts and interconnections, Appl. Phys. Lett. 69, 3560 (1996). [iv] A. Joi, R. Akolkar, U. Landau, Pulse plating of copper germanide, Appl. Phys. Lett. 102, 134107 (2013).

SYLLABLE-BASED SPEECH RECOGNITION USING ELECTROMYOGRAPHY AND DECISION SET CLASSIFIER

During the speech, contractions of muscles in the speech apparatus produce myoelectric signals that can be picked up by electrodes, filtered and analyzed. The problem of extraction of speech information from these signals is significant for patients with damaged speech apparatus, such as laryngectomy patients, who could use speech recognition based on myoelectric signal classification to communicate by means of the synthetic speech. In the most previously conducted research, classification is performed on a ten word vocabulary which resulted in a good classification rate. In this paper, a possibility for myoelectric syllable based speech classification is analyzed on a significantly larger vocabulary with novel decision set based classifier which is simple, easy to adapt, convenient for research and similar to the way humans think. In order to have a high quality of recorded myoelectric signals, analysis of the optimal position of electrodes is performed. Classification is performed by comparison between syllable combination and whole words. Based on classification rate, words can belong to easy, medium or hard to distinguish group. Results based on generated list of best matching combinations show that decision set analysis of myoelectric signals for speech recognition is a promising novel method.

Electrochemical Properties of Pulse Plating Amorphous Ni-Mo-W Alloy Coating in Alkaline Medium

Abstract The amorphous Ni-Mo-W alloy coating with high HER (hydrogen evolution reaction) activity was obtained by pulse plating. In view of HER overpotential, the optimum electrodeposition conditions to prepare Ni-Mo-W coating in pulse plating process were determined, e.g. Na 2 WO 4 ·2H 2 O concentration, average current density and duty cycle. Correspondingly, the effects of molybdenum and the tungsten contents on the compositions and the components of Ni-Mo-W coatings were investigated systematically. The results show that adding tungsten into Ni-Mo binary alloy coating could increase the HER activity effectively (η 200 = 80 mV) and the amorphous microstructure of Ni-Mo-W coating mainly depends on the molybdenum content. After long-term electrolysis, compared with amorphous Ni-Mo coating, the electrochemical stability of amorphous Ni-Mo-W coating is improved to some extent due to the poor dissolution of molybdenum and tungsten.

Ulnar motor study to first dorsal interosseous: Best reference electrode position and normative data.

Reference electrode position affects nerve conduction study results. This study was undertaken to determine the optimal reference electrode position for ulnar motor recording from the first dorsal interosseous (FDI) muscle and to develop normative data. Fifty-one subjects were tested using reference electrode positions on the thumb, index, and little fingers. Latencies were compared with a needle recording from the FDI. Analysis was performed to determine the surface placement that most closely matched the needle recording latency. A normative database was then derived on 100 healthy subjects. Placing the reference electrode on the thumb yielded results closest to the "gold standard" needle recording latency. The 97th percentile (upper limit of normal) for latency was 4.0 ms. The 3rd percentile values (lower limit of normal) for amplitude were 9.0 mV for men and 9.3 mV for women. The reference position on the thumb yields latencies that most closely approximate needle recording. Normative data are presented.

Morphological and Compositional Analysis of Electrodeposited Indium (III) Sulfide (In2S3) Films

Within the last few years, there has been notable progress in understanding the growth mechanisms of semiconductor thin films for photovoltaic (PV) applications. Electrodeposition continues to be a complex deposition technique that can lead to regions of low quality (for example, cracks) in films. Such cracks can form porous zones on the substrate and diminish the heterojunction interface quality of a PV cell. In this paper, electrodeposition of In2S3 films was systematically and quantitatively investigated by varying electrodeposition parameters including bath composition, current density, deposition time, and deposition temperature. Their effects upon the morphology, composition, and film growth mechanism were studied with the help of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and digital imaging analysis (using fracture and buckling analysis software). In addition, the effect of different annealing treatments (200°C, 300°C, and 400°C in air) and coated glass-substrates (Mo, ITO, and FTO) upon the properties of the In2S3 films was analyzed. Furthermore, the Taguchi/Design of Experiments (DOE) Method was used to determine the optimal electrodeposition parameters in order to improve the properties.

Nano-micro structured superhydrophobic zinc coating on steel for prevention of corrosion and ice adhesion

Thin films of zinc have been deposited on steel substrates by electrodeposition process and further functionalized with ultra-thin films of commercial silicone rubber, in order to obtain superhydrophobic properties. Morphological feature, by scanning electron microscope (SEM), shows that the electrodeposited zinc films are composed of micro-nano rough patterns. Furthermore, chemical compositions of these films have been analyzed by X-ray diffraction (XRD) and infra-red (IRRAS). An optimum electrodeposition condition, based on electrical potential and deposition time, has been obtained which provides superhydrophobic properties with a water contact angle of 155±1°. The corrosion resistance properties, in artificial seawater, of the superhydrophobic zinc coated steel are found to be superior to bare steel. Similarly, the measured ice adhesion strength on superhydrophobic surfaces, using the centrifugal adhesion test (CAT), is found to be 6.3 times lower as compared to bare steel. This coating has promising applications in offshore environment, to mitigate corrosion and reduce ice adhesion.

Abstract 150: Small Variations in Defibrillation Electrode Placement Affect Shock Success

Background: Defibrillation is essential in treating cardiac arrest patients with ventricular fibrillation (VF). The success of the shock in terminating VF depends on many previously studied factors, including waveform and energy dose. It has been observed clinically that defibrillation electrode placement varies widely. The goal of this study was to assess the effect of small differences in defibrillation electrode placement on first shock defibrillation success rates in swine. Methods: In 10 anesthetized swine weighing 32.7 ± 2.5 kg (mean ± standard deviation), electrode pads were attached at 3 different symmetric positions: the medial edge of each electrode was placed 3% (2.1 ± 0.1 cm), 7% (4.7 ± 0.1 cm), or 11% (7.5 ± 0.2 cm) around the circumference of the chest from mid-sternum (Fig. 1). Biphasic impedance-compensated shocks were delivered through the pads with a 50-ohm resistor added in series to replicate human impedance. The order of the 3 positions was block randomized for each experiment. At each electrode position, 24 episodes were run: VF was electrically induced and up to 2 shocks were delivered. Primary outcome was defined as successful VF termination after the first shock; secondary outcome was the cumulative success of both the first and second shock. Results: Across all experiments, at the 3%, 7%, and 11% positions, first shock success was 38.3% (92/240), 48.3% (116/240), and 36.7% (88/240) (p = 0.02, Chi-square Test); cumulative 2-shock success was 59.6% (143/240), 63.8% (153/240), and 55.4% (133/240) (p = 0.18), respectively. The lowest first shock success was at the 3% position in 6 of 10 animals, at the 11% position in 4 of 10 animals, and never at the 7% position. Conclusions: Small changes in electrode pad placement can significantly affect defibrillation shock success. Although anatomic differences may prevent the existence of one optimal electrode position, one position may be more effective for VF termination than another in a given patient.

What is the optimal anodal electrode position for inducing corticomotor excitability changes in transcranial direct current stimulation?

Transcranial direct current stimulation (tDCS) non-invasively modulates brain function by inducing neuronal excitability. The conventional hot spot for inducing the highest current density in the hand motor area may not be the optimal site for effective stimulation. In this study, we investigated the influence of the center position of the anodal electrode on changes in motor cortical excitability. We considered three tDCS conditions in 16 healthy subjects: (i) real stimulation with the anodal electrode located at the conventional hand motor hot spot determined by motor evoked potentials (MEPs); (ii) real stimulation with the anodal electrode located at the point with the highest current density in the hand motor area as determined by electric current simulation; and (iii) sham stimulation. Motor cortical excitability as measured by MEP amplitude increased after both real stimulation conditions, but not after sham stimulation. Stimulation using the simulation-derived anodal electrode position, which was found to be posterior to the MEP hot spot for all subjects, induced higher motor cortical excitability. Individual positioning of the anodal electrode, based on the consideration of anatomical differences between subjects, appears to be important for maximizing the effects of tDCS.

Investigation of optimal position for implantable loop recorders by potential mapping with Reveal DX

BackgroundElectrode positioning is important for the operation of implantable loop recorders (ILRs). This study aimed to investigate optimal electrode positions for the implantation of ILRs. MethodsFifteen male subjects participated in the study and R wave amplitude data were collected from 15 areas in the left anterior chest area, with 4 variations of electrode angles and body positions. ResultsThe estimated minimum R wave amplitude values were greater than 0.3mV (manufacturer-recommended value) when electrodes were angled vertically and positioned on the midclavicular line of the third and the forth intercostal spaces or on the left sternal border of the fourth and fifth intercostal space and when angled at 45° to the right on the left sternal border of the third and the forth intercostal space. ConclusionsExploring areas around the left sternal border of the fourth intercostal space – where the R wave amplitudes are least affected by body positions – is a reliable method for choosing implantation locations for ILRs.

Asymmetrical Supercapacitor Composed of Thin Co(OH)2 Nanoflakes on Three-Dimensional Ni/Si Microchannel Plates with Superior Electrochemical Performance

Nanoscale cobalt hydroxide (Co(OH)2) particles are fabricated by electrodeposition on three-dimensional nickel/silicon microchannel plates (Ni/Si-MCPs) as the active electrode materials on the surface and sidewall of the Ni/Si-MCPs for miniature supercapacitors. The relationship among the electrodeposition time, morphology, formation mechanism of Co(OH)2 nanostructure, and capacitor performance is studied. Using an optimal electrodeposition time of 6min, the Co(OH)2 supercapacitor has a capacitance of 697.56Fg−1 (5.72Fcm−2) at 2mAcm−2 and the retention ratio is 91.20% after 2500 cycles. The large areal capacitance and excellent rate capability can be attributed to the unique 3D ordered porous architecture which facilitates electron and ion transport, enlarges the liquid-solid interfacial area, and enhances the utilization efficiency of the active materials. Meanwhile, the weight and size of the device are reduced. By using the Co(OH)2/Ni/Si-MCPs electrode as the positive electrode and CNTs/nickel foam (CNTs/NF) as the negative electrode, the device assembled with CR2025 batteries exhibits high energy density (38.39Whkg−1), high power density (5400Wkg−1 at 9.67Whkg−1), and stable power characteristic (2000 times with 80.63% retention). After charging each supercapacitor for 10s, the device can power a 5mm diameter light-emitting diode (LED) with different colors efficiently, for example, a blue LED for 20min.

Electrodeposition, Morphology, Composition, and Corrosion Performance of Zn-Mn Coatings from a Deep Eutectic Solvent

Different Zn-Mn coatings were successfully electrodeposited on copper substrates from deep eutectic solvent-based electrolytes containing boric acid as an additive. The main objective of this work was to optimize the Zn/Mn ratios and morphologies of the as-electrodeposited Zn-Mn films in order to obtain better corrosion protection performance coatings. The electrodeposition behaviors of Zn-Mn alloys as studied by cyclic voltammetry showed that with increase in electrolyte Mn(II) concentration, Zn(II) ion reduction occurs at higher overpotentials while Mn reduction occurs at lower overpotentials, and this in turn enhances Mn incorporation into the deposit. Characterization results showed that the electrodeposition potential and electrolyte Mn(II) concentration significantly affects the Mn content, crystal structure, surface morphology, and corrosion performance of the deposits. With increase in electrodeposition potential and electrolyte Mn(II) concentration, the alloy Mn increased and the grain morphology was refined. The crystal structure of Zn-Mn deposits consists of Zn and hexagonal close packed e-phase Zn-Mn at low electrodeposition potentials and low electrolyte Mn(II) content. However, at high electrodeposition potentials and electrolyte Mn(II) contents, the crystal structure was only composed of hexagonal close packed e-phase Zn-Mn. Corrosion measurements show that all the Zn-Mn samples have a passivating behavior and exhibits higher corrosion resistances when compared to those from aqueous solutions. Thus, optimum electrodeposition potential and electrolyte Mn(II) concentration were determined producing compact Zn-Mn films with the best corrosion resistance.

Pool boiling enhancement through microporous coatings selectively electrodeposited on fin tops of open microchannels

Abstract Open microchannels and microporous coatings have been individually employed by previous investigators for enhancing pool boiling heat transfer. In this paper, their combined effect is investigated by electrodepositing microporous coatings on the fin tops of microchannels. The microporous coatings were applied using the optimal electrodeposition parameters developed in an earlier study. The effect of microchannel geometry on heat transfer performance for water boiling at atmospheric pressure on 10 mm × 10 mm copper chips is reported here. A maximum critical heat flux (CHF) of 3250 kW/m 2 was obtained for Chip 9 with fin width = 200 μm, channel width = 500 μm and channel depth = 400 μm at a wall superheat of 7.3 °C. A maximum value of heat transfer coefficient (HTC) of 995 kW/m 2 °C was achieved for Chip 12 with a different channel width of 762 μm for a heat flux of 2480 kW/m 2 at a wall superheat of 2.5 °C. Bubble growth and heat transfer processes are altered when nucleation takes place preferentially on the fin tops. Visual studies indicate a microconvective mechanism in which bubbles leaving from the fin tops induce strong localized liquid circulation currents in the microchannels. A liquid microcirculation based theoretical model is developed to predict heat transfer under this mechanistic description. The preliminary results are in good agreement with the experimental data.

Nitrate Reduction at Electrodeposited Copper on Copper Cathode

We report on the synthesis and characterization of low-cost copper electrodeposited on a copper substrate (Cu/Cu), and its applicability towards nitrate reduction. The surface area of Cu was increased by the electrodeposition of Cu, and at a chosen deposition potential and pH, optimum electrodeposition parameters corresponding to better catalytic activity of nitrate reduction were determined. The electrodeposited catalysts were physically characterized using scanning electron microscopy and X-ray diffraction. Cyclic voltammetry was employed to screen the catalytic activity of the electrodeposited Cu/Cu catalysts towards nitrate reduction. Electrolysis was performed using potentiostatic technique and the effect of potential was studied. Product analysis showed 10% increase in nitrate removal efficiency on Cu/Cu system over bare Cu. Nitrate removal efficiency up to 97% was achieved while treating high concentration (1 M) nitrate with the optimized Cu/Cu cathode.

Electrochemical reconstruction of a heavily corroded Tarentum hemiobolus silver coin: a study based on microfocus X-ray computed microtomography

In this paper we report on the electrochemical reconstruction of a Tarentum hemiobolus Ag coin, severely corroded in marine environment. As assessed by conventional analytical tools, most of the initially metallic Ag coin had been converted to AgCl by exposure to the aggressive coastal burial conditions. X-ray computed microtomography proved that only small portions of the artefact had preserved their metallic nature. Since the engraving was preserved partly in the corrosion product bulk and partly in the metallic rests, electrodeposition of Ag from the AgCl layer, under controlled conditions ensuring shape preservation, resulted in the reconstruction of the coin surface with full recovery of the original engraving. Such optimal electrodeposition conditions were identified by a combination of electrochemical and quasi-in situ X-ray microtomography experiments, carried out with artificially corrored engraved Ag wires. Microtomography of the reconstructed coin confirmed the compaction of the external Ag layer and disclosed that the central core of the coin still contains unconverted AgCl. The presence of such a mineralised core does not however impact the numismatic use of the coin and the safeguard of the original engraving.

Electrodeposition of DLC films on carbon steel from acetic acid solutions

In this paper the electrodeposition of DLC films on carbon steel from aqueous acetic acid solutions and their structural and mechanical characterization are reported. The process is performed at room temperature at relatively low cell voltages (from −8 to −20 V) with entirely environmentally friendly chemicals. Qualitative and quantitative evaluation of C hybridisation type have been performed by Raman spectroscopy. Microhardness and adhesion of the supported electrodeposited films have been measured by micro-indentation and scratch-testing. Notably, ductile failure was found to correspondence to a wide range of film growth conditions. The corrosion resistance of DLC-coated steel has been assessed by electrochemical impedance spectrometry in a neutral chloride solution. Optimal electrodeposition conditions were identified for the formation of high-quality DLC films ca. 270 nm thick with a high content of diamond-coordinated carbon and an ideal combination of hardness and adhesion; films formed under these conditions also confer some degree of corrosion protection to the steel substrate.