Gold Plating Research Articles

On the electrode configurations in a large single phase liquid xenon detector for dark matter searches

In the near future there will be the request for very large liquid Xenon (LXe) detectors for Dark Matter (DM) searches in the 50-ton range. To avoid an impractically long, single drift space of a dual-phase detector, it seems beneficial to use the single-phase technique. Since electrons then can drift in any direction, we can segment the homogeneous medium and thus avoid an excessive maximum drift path of order 4 m. The shorter detector length has several benefits, e.g. requiring a lower cathode voltage for the same drift field. We can easily split the TPC into two regions with the cathode in the center and two anodes at the top and bottom. One also can use multiple TPCs stacked on top of each other in the same liquid volume to reduce the maximum drift length even further.A further division of the drift space by installing an additional anode in the center would require S2 photons to traverse the liquid for several times the Rayleigh scattering length in LXe, which is only 30–40 cm. This seems to be excessive for good x-y localization. We therefore suggest a geometry of two independent TPCs with two drift spaces each.Despite earlier publications concerns persisted about the effect of shadowing. A detailed FEM model of the anode regions shows that with an aligned wire arrangement the drifting electrons impinge sideways on the anode in a narrow angular range of width 15°–20°. Most S2 photons are emitted in full view of the close-by PMT array. About 37% of the S2 photons are shadowed by the anode wire out of which 30% will be reflected back again on the gold plating of the wires. Thus we can observe 74% of the total S2 light. Compared to a dual-phase detector, however, we do not suffer from the extraction efficiency, sometimes reported as low as 50%.

Two Approaches to the Laser-Induced Formation of Au/Ag Bimetallic Nanoparticles in Supercritical Carbon Dioxide.

Two approaches are proposed for the synthesis of bimetallic Au/Ag nanoparticles, using the pulsed laser ablation of a target consisting of gold and silver plates in a medium of supercritical carbon dioxide. The differences between the two approaches related to the field of “green chemistry” are in the use of different geometric configurations and different laser sources when carrying out the experiments. In the first configuration, the Ag and Au targets are placed side-by-side vertically on the side wall of a high-pressure reactor and the ablation of the target plates occurs alternately with a stationary “wide” horizontal beam with a laser pulse repetition rate of 50 Hz. In the second configuration, the targets are placed horizontally at the bottom of a reactor and the ablation of their parts is carried out by scanning from above with a vertical “narrow” laser beam with a pulse repetition rate of 60 kHz. The possibility of obtaining Ag/Au alloy nanoparticles is demonstrated using the first configuration, while the possibility of obtaining “core–shell” bimetallic Au/Ag nanoparticles with a gold core and a silver shell is demonstrated using the second configuration. A simple model is proposed to explain the obtained results.

Physical Vapor Deposition as an Economical Alternative to Gold Plating in Imitation Jewelry

Jewelry is one of the products that depend on the aesthetic aspect and to increase the aesthetic values. There are many ways to give it a shiny appearance and bright colors, but it has a high cost. Physical vapor deposition is one of the methods that increase aesthetic values as it adds many colors to the surface of the product and is similar to precious metals. Where the research problem lies in the possibility of using different coatings from alternatives to precious ores in the production of imitation jewelry and verifying its suitability to give quality qualities of color and luster and the goal of the research is to find alternatives to plating metals with the same degree of luster of precious metals, coating imitation jewelry with a low-cost coating with aesthetic values And constant bright colors, and upgrading the Egyptian counterfeit jewelry industry to enable it to compete with its expatriate counterparts. The importance of the research lies in the production of multiple layers of paint with multiple colors and a long-life span, and finding economical ways to paint imitation jewelry to raise the competitiveness of the Egyptian product. The research assumes that coating imitation jewelry with similar layers of precious metals has bright colors, lower economic cost and longer life span. The research follows a descriptive and analytical approach. One of the most important results of the research is to obtain the colors of precious metals For jewelers.

New method of recording the functional activity pattern of the buccinator from the mucosal surface

ObjectivesThe buccinator (BUC) is an important muscle for oral function. Since it lies deep in the facial skin, recording its activity is difficult; thus, studies on its function are limited. We developed a method to access the deep facial muscles from the mucosal side. The aim of this study was to test the reliability of the new recording method for the BUC and to investigate the BUC behavior in typical facial functions. MethodsTo evaluate the new method, BUC activities were recorded simultaneously with a gel-type electrode on the skin and the newly developed surface electrode on the buccal mucosa. Electromyographic (EMG) activities in function, such as chewing and swallowing, along with the activities of the lower orbicularis oris (OO), zygomaticus major, masseter, and digastric muscles, were compared using the two recording methods. EMG activities among various tasks were compared using normalized values based on those obtained during maximum lip closure (MaxLC). ResultsThe new surface electrode was made of gold plates on a thin plastic fixed to a stainless-steel wire frame and weighed less than 1 g. The BUC activity recorded from the mucosa was the highest during a corner-pulling task and was low during clenching. The BUC was active during MaxLC, similar to the OO, and the BUC activity pattern among tasks recorded from the mucosa was identical to that reported by previous studies using intramuscular electrodes. The new electrode evaluated the BUC activities quantitatively, and the recordings by the new electrode were free from contamination. ConclusionsThe findings of this study confirmed the reliability of the new BUC recording method. It could be easily placed correctly within seconds, without the need for cleansing or sterilizing the skin. The BUC and OO were active during a MaxLC task, indicating that the BUC assists lip closure by pulling the corners of the mouth. The basic facial functions evaluated, including chewing, were similar to those studied by intramuscular electrodes.

A gemmological study of the reliquary crown of Namur, Belgium

Abstract. The reliquary crown, hosted in the diocesan museum of Namur, was produced during the beginning of the 13th century to shelter a fragment of the holy crown of thorns. This beautiful piece of goldsmithery is made of eight gold plates, topped by round lobes, and connected to each other by hinges blocked with a pin decorated by a pearl. The crown is decorated by filigrees, flowers, and approximately 400 pearls and coloured (green, reddish pink, turquoise, red, blue) stones showing simple cutting with various sizes and shapes. Raman and portable X-ray fluorescence spectrometer (pXRF) techniques have been used to determine the nature and sources of all samples, as well as the composition of filigrees. Analyses have identified emeralds from Pakistan, reddish pink spinels from Tajikistan, red almandine garnets from India, turquoise from Iran, blue sapphires from Sri Lanka or Myanmar, and European pearls. The filigrees contain approximately 86 wt % Au, 7 wt % Ag, and 7 wt % Cu, thus confirming a gold-rich composition. The gemstones, contemporary with the crown, probably arrived in Europe by the silk trade road.

High-performance 1-10 THz integrating sphere.

The SPICA far-infrared instrument (SAFARI), one of instruments of the space infrared telescope for cosmology and astrophysics, requires a calibration source assembly to calibrate the transition edge sensor readout circuits. A high-performance integrating sphere working at SAFARI wavelength (34-230 µm) is essential. A novel process for preparing terahertz integrating spheres was developed. The aluminum surfaces after sandblasting, wet-etching, and gold plating processes demonstrate rough morphology but high reflectance of 0.91 in 1-10 THz. The spatial distribution of the measured output power excellently agrees with the numerical simulation results based on the assumption of uniform surface radiation at the output port.

Structure, morphology and absorption characteristics of gold nanoparticles produced via PLAL method: Role of low energy X-ray dosage

This paper reports the effects of low energy X-ray irradiation doses on the structures, morphologies and absorbance of some colloidal gold nanoparticles (AuNPs) produced in distilled water via the one-step pulse laser ablation in liquid (PLAL) method. An Nd:YAG pulse laser (wavelength of 1064 nm and fluence ranges of 0.076–7.692 J/cm2) was used to ablate the gold plate surface (acted as a target) immersed in distilled water (10 mL). The laser pulse duration was adjusted to 2.5 min (1000 pulses), 5 min (2000 pulses). Simultaneously, the colloidal suspension was irradiated with low energy X-ray. The obtained samples were characterized thoroughly using different analytical instruments. High quality, pure, surfactant-free AuNPs with well-defined morphology and broad size distribution were achieved. The recorded values of the Zeta potential of the as-synthesized AuNPs were increased from -33.1 to -41.2 mV which was mainly due to the low energy X-ray dose-mediated photo- and Auger-electrons generation plus the fragmentation of the bigger NPs into highly stable tinier species inside the colloidal suspension. The observed blue-shift in the absorbance peaks of the NPs centered at 523, 529, and 526 nm irradiated with the corresponding fluences of 0.076, 3.846, and 7.692 J/cm2 was ascribed to the quantum size effects. It is established that the synergy between laser ablation and low energy X-ray does may be effective to prepare the contaminants-free AuNPs in the liquid suspension in a simple rapid and cost-effective way.

Inicjały iluminatorskie w inkunabułach z oficyny Antona Kobergera

In the article the author analyses a set of incunabula from the collection of the Raczyński Library in Poznań, characterised by a uniformity of illuminated initials. Formal features of the initials point to the so-called Koberger type developed by illuminators collaborating with the famous Nuremberg printer Anton Koberger. The Koberger initials, which have been studied by very few German scholars, are characterised by stems filled with colourful acanthus leaves or gold plates. The letters are presented on an ornamental fleuronné or golden background. They are usually surrounded by characteristic frames made up of alternating — usually green and red — sections. The initials from the Poznań books, which display such features, are divided in the article into three groups and compared with illuminations from Koberger books from other European libraries. A formal and stylistic comparison makes it possible to date the illumination in the Poznań books fairly precisely, and to attribute it hypothetically to Koberger’s workshop or illuminators imitating the Koberger style.

Gold, Silver, and Electrum Electroless Plating on Additively Manufactured Laser Powder-Bed Fusion AlSi10Mg Parts: A Review

Additive manufacturing (AM) revolutionary technologies open new opportunities and challenges. They allow low-cost manufacturing of parts with complex geometries and short time-to-market of products that can be exclusively customized. Additive manufactured parts often need post-printing surface modification. This study aims to review novel environmental-friendly surface finishing process of 3D-printed AlSi10Mg parts by electroless deposition of gold, silver, and gold–silver alloy (e.g., electrum) and to propose a full process methodology suitable for effective metallization. This deposition technique is simple and low cost method, allowing the metallization of both conductive and insulating materials. The AlSi10Mg parts were produced by the additive manufacturing laser powder bed fusion (AM-LPBF) process. Gold, silver, and their alloys were chosen as coatings due to their esthetic appearance, good corrosion resistance, and excellent electrical and thermal conductivity. The metals were deposited on 3D-printed disk-shaped specimens at 80 and 90 °C using a dedicated surface activation method where special functionalization of the printed AlSi10Mg was performed to assure a uniform catalytic surface yielding a good adhesion of the deposited metal to the substrate. Various methods were used to examine the coating quality, including light microscopy, optical profilometry, XRD, X-ray fluorescence, SEM–energy-dispersive spectroscopy (EDS), focused ion beam (FIB)-SEM, and XPS analyses. The results indicate that the developed coatings yield satisfactory quality, and the suggested surface finishing process can be used for many AM products and applications.

Gold-Nanoparticle Synthesization In Gum Arabic Solution By Pulsed Laser Ablation

Green synthesis of nanoparticles is crucial to effectively reduce the risk to the environment by eradicating hazardous components that are harmful to human health. The broad complications such as aggregation and oxidation of nanoparticles will potentially limit their usage. Gum Arabic (GA) has attained decent attention due to less toxicity and bio-compatibility with metals. Gold-nanoparticles (Au-NPs) have several applications in diagnosing cancer, targeted delivery of drugs and in cancer treatment. This project is conducted by synthesizing Au-NPs in GA solution via pulsed laser ablation in liquid (PLAL) technique at varied laser fluences. A Q-switched Nd:YAG laser with wavelength of 1064 nm was focused using a lens with a focal length of 80 mm to ablate a gold plate immersed in GA solution. Four different laser fluences were tested. The laser fluences were 0.203, 0.214, 0.250 and 0.272 J. The Au-NPs synthesized in the GA solution were then characterized using photoluminescene (PL) and UV-Visible double beam spectrometer (UV-Vis). The highest laser fluence has shown the highest intensity while the wavelength of all peaks is the same indicating the same nanomaterials being synthesized in each sample. The UV-Vis spectra indicated that the absorbance increases as the holding time is prolonged. It is believed that the formation of Au-NPs is a nucleating process and followed by a growing process.

Very Low Resistance Al/Cu Joints for Use at Cryogenic Temperatures

We present two different techniques for achieving low resistance ($<$20 n$\rm \Omega$) contacts between copper and aluminium at cryogenic temperatures. The best method is based on gold plating of the surfaces in an e-beam evaporator immediately after Ar plasma etching in the same apparatus, yielding resistances as low as 3 n$\rm \Omega$ that are stable over time. The second approach involves inserting indium in the Al/Cu joint. For both methods, we believe key elements are surface polishing, total removal of the aluminum oxide surface layer, and temporary application of large (typ. 11 kN) compression forces. We believe the values for gold plated contacts are the lowest ever reported for a Cu/Al joint of a few $\rm cm^{2}$. This technology could simplify the construction of thermal links for advanced cryogenics applications, in particular that of extremely low resistance heat switches for nuclear demagnetization refrigerators.

A Tunable Perfect THz Metamaterial Absorber with Three Absorption Peaks Based on Nonstructured Graphene

In this paper, a graphene-based tunable multi-band terahertz absorber is proposed and numerically investigated. The proposed absorber can achieve perfect absorption within both sharp and ultra-broadband absorption spectra. This wide range of absorption is gathered through a unique combination of periodically cross- and square-shaped dielectrics sandwiched between two graphene sheets; the latter enables it to offer more absorption in comparison with the traditional single-layer graphene structures. The aforementioned top layer is mounted on a gold plate separated by a Topas layer with zero volume loss. Furthermore, in our proposed approach, we investigated the possibility of changing the shapes and sizes of the dielectric layers instead of the geometry of the graphene layers to alleviate the edge effects and manufacturing complications. In numerical simulations, parameters, such as graphene Fermi energy and the dimensions of the proposed dielectric layout, have been optimally tuned to reach perfect absorption. We have verified that the performance of our dielectric layout called fishnet, with two widely investigated dielectric layouts in the literature (namely, cross-shaped and frame-and-square). Our results demonstrate two absorption bands with near-unity absorbance at frequencies of 1.6–2.3 and 4.2–4.9 THz, with absorption efficiency of 98% in 1.96 and 4.62 THz, respectively. Moreover, a broadband absorption in the 7.77–9.78 THz is observed with an absorption efficiency of 99.6% that was attained in 8.44–9.11 THz. Finally, the versatility provided by the tunability of three operation bands of the absorber makes it a great candidate for integration into terahertz optoelectronic devices.

Effects of four carboxyl-containing additives on imitation gold electroplating Cu-Zn-Sn alloys in an HEDP system

The requirements for using noncyanide imitation gold plating as decorative electroplating are increasing; thus, continuously improving the quality of the coating of the imitation gold plating and optimizing the coating process have become the current priority. In this experiment, hydroxyethylidene diphosphonic acid (HEDP) was used as the main complexing agent; CuSO4·5H2O, ZnSO4·7H2O, and NaSnO3·3H2O were the main salts; and NaOH and sodium carbonate were used as the buffers to prepare the electroplating solution. Using sodium citrate (SC), sodium potassium tartrate (SS), sodium gluconate (SG), and glycerol (Gl) as four additives, the effects of the number of carboxyl groups on the properties of a Cu-Zn-Sn alloy coating were compared. The electrochemical analysis showed that Cu-Zn-Sn alloy codeposition occurred at -0.50 Vvs.Hg|HgO. The scanning electron microscopy (SEM) results showed that the grain size of the coatings obtained with carboxyl-containing additives was more uniform than that obtained with the electroplating solution without additives. The X-ray fluorescence spectrometry (XRF) analysis revealed that the composition of the Cu-Zn-Sn alloy coating obtained by using SC as an additive in the electroplating solution was 89.75 wt% Cu, 9.61 wt% Zn, and 0.64 wt% Sn, and the color of the coating was golden yellow. The X-ray diffraction (XRD) pattern showed that the coating was a mixture of Cu, Cu5Zn8, CuSn, Cu6Sn5, and CuZn phases. The analysis of the electroplating solution by UV, IR, and NMR spectroscopy methods indicates that the additives improve the coating by affecting the complexation reaction of metal ions. These results can provide technical guidance for developing Cu-Zn-Sn ternary alloy electrodeposition technology with the new cyanide-free HEDP alkaline electroplating system.

Low-Cost Bipolar Plates of Ti4O7-Coated Ti for Water Electrolysis with Polymer Electrolyte Membranes.

Although hydrogen is expected to play an important role in the storage of energy from renewable energy sources, technology to produce hydrogen at low cost is needed for its widespread use. The key to the low-cost production of hydrogen with a polymer electrolyte membrane (PEM) water electrolysis system, which is widely used today, is to replace the Au- or Pt-coated Ti with a low-cost material that can be manufactured from inexpensive, corrosion-resistant, and conductive components. We studied titanium suboxide (Ti4O7)-coated titanium (Ti) bipolar plates, which can be substituted for commonly used Pt-coated Ti bipolar plates, as an inexpensive way of producing the PEM water electrolysis system. The water electrolysis characteristics of the cell were evaluated using Ti4O7-sputtered Ti for the bipolar plates of the water electrolysis cell, and the applicability of Ti4O7-sputtered Ti was investigated. The Ti4O7-sputtered Ti had a very low contact resistance (4–5 mΩ cm2) before and after voltage application that was equivalent to that of gold or platinum plating. The efficiency of water electrolysis in this study was comparable to those of previous reports using bipolar plates coated with precious metals. This development opens the door for fabrication of low-cost electrolyzers as well as related electrochemical devices such as fuel cells, sensors, catalysts, and air or liquid cleaning devices.

Electroless deposition of Ni-P/Au coating on Cu substrate with improved corrosion resistance from Au(iii)-DMH based cyanide-free plating bath using hypophosphite as a reducing agent.

The green cyanide-free gold deposition is an important development direction in electroless gold plating. However, the commonly Au(i) based cyanide-free gold plating bath always suffers from severe corrosion to the Ni–P layer and unsatisfactory service life of the bath. In this work, a green and environmentally friendly cyanide-free gold plating bath was developed with hypophosphite added as a reducing agent into the Au(iii)–DMH (5,5-dimethylhydantoin) based plating bath to retard the corrosion of the Ni–P layer. SEM micrographs combined with XRD and XPS analysis indicated that the electroless deposited gold was pure and compact. And XRD also revealed that the oriented deposition of gold was growing preferentially on Au (111). Corrosion tests, including salt spray tests, potentiodynamic polarization tests, and electrochemical impedance spectroscopy tests, indicated that the obtained Cu/Ni–P/Au coatings had significantly improved corrosion resistance performance with the loading of hypophosphite as the reducing agent. The baths remained transparent and no turbidity or precipitates were detected for 210 days, reflecting good stability. The detection for the Ni2+ concentration in the bath showed that adding hypophosphite could retard the replacement reaction between Au3+ and the Ni–P layer in part and this is important for decreasing the severe corrosion of the Ni–P layer. Moreover, Au was inactive for catalyzing the oxidation of hypophosphite during the deposition process which was confirmed furthermore via quantum chemical calculations. Therefore, our developed green cyanide-free electroless gold deposition process can beneficially provide research value and application prospects in microelectronic industry.

Electroless Gold Plating in Alkaline and Slightly Acidic Solutions

Electroless Gold Plating in Alkaline and Slightly Acidic Solutions

How Joseph Smith Encountered Printing Plates and Founded Mormonism

ABSTRACTDid Joseph Smith, the founder of Mormonism, really find gold plates? This article considers that basic question from a new materialist perspective. Drawing on textual and material-bibliographical evidence, it argues that Smith, and possibly also a group of witnesses, may have had a formative physical encounter with a set of plates and that this encounter was partly responsible for provoking the events and interpretations that followed. These plates could have been either stereotype plates or copper plates, both commonly used for industrial printing in the nineteenth-century United States. This article also takes the empirical investigation into what Smith may have encountered as an occasion to reflect, methodologically and theoretically, on the role of ordinary material objects in processes of religious and historical change.

Comparison of Corrosion Products From Implant and Various Gold-Based Abutment Couplings: The Effect of Gold Plating.

This study compared titanium (Ti), palladium (Pd), platinum (Pt), and gold (Au) ion release following induced accelerated tribocorrosion from three Au alloy abutment groups coupled with Ti implants over time; investigated contacting surface structural changes; and explored the effect of Au plating. Three abutment groups, G (n = 8, GoldAdapt, Nobel Biocare), N (n = 8, cast UCLA, Biomet3i), and P (n = 8, cast UCLA, Biomet3i, Au plated), coupled with implants (Nobel Biocare), immersed in 1% lactic acid, were cyclically loaded. Ions released (ppb) at T1, T2, and T3, simulating 3, 5, and 12 months of function, respectively, were quantified by inductively coupled plasma mass spectrometry (ICP-MS) and compared. Surface degradation and fretted particle composition after T3 were evaluated with scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDX). ICP-MS data were nonparametric, expressed as medians and interquartile ranges. SEM/EDX showed pitting, crevice corrosion, and fretted particles on the components. Released ion concentrations in all groups across time significantly decreased for Pd (P < .001, median range: 1.70-0.09), Pt (P = .021, 0.55-0.00), and Au (P < .001, 1.01-0.00) and increased for Ti (P = .018, 2.49-5.84). Total Ti release was greater than other ions combined for G (P = .012, 9.86-2.30) and N (P < .001, 13.59-5.70) but not for P (P = .141, 8.21-3.53). Total Ti release did not differ between groups (P = .36) but was less variable across group P. On average, total ion release was 13.77 ppb (interquartile range 8.91-26.03 ppb) across the 12-month simulation. Tribocorrosion of Ti implants coupled with Au abutments in a simulated environment was evidenced by fretted particles, pitting, and crevice corrosion of the coupling surfaces and release of ions. More Ti was released compared with Pd, Pt, and Au and continued to increase with time. Abutment composition influenced ion release. Au-plated abutments appeared to subdue variation in and minimize high-concentration spikes of titanium.

Gold Plating

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Gold（I）Complexes of Hydantoin Derivatives and Their Properties

Among hydantoin derivatives, a monovalent gold complex was obtained when 1-methylhydantoin（MH）and hydantoin（HY）were used as ligands. These are more beneficial for use in gold plating solutions than trivalent gold complex of 5,5-dimethylhydantoin（DMH）. Moreover, these complexes can be extracted as crystals. Therefore, the chlorine concentration, constituting a major impurity in gold plating for the electronics industry, can be kept low. Each crystal coordinated two hydantoin derivatives to gold and had water of crystallization. The gold-HY complex solution is stable at pH 5-9. Moreover, no change in pH or decomposition occurs even when hydrogen peroxide is added. Higher stability can be expected in the gold plating solution than for gold sulfite.