Academic literature on the topic 'Platinum-zinc alloy'

The procedure for the identification of white jewelry alloys based on precious metals, in particular, silver, platinum and platinum group metals with different contents of alloying components, by testing on an assay stone and by the method of X-ray fluorescence analysis has been considered. The methodology for assessing the compliance of silver and platinum fineness in white jewelry alloys of different component composition with the requirements of regulatory documents and the procedure for their identification has been improved. It has been established that the silver fineness in precious alloys of the AgCu, AgZnCu system, determined using the potassium dichromate reagent on the test stone, depends on the manifestation of the contrast of the qualitative reaction from the standard sample (assay needle). It has been proven that for testing silver alloys containing palladium, the "Acid reagent for gold 750" is effective, which works to determine the qualitative and approximate content of silver in alloys. It was determined that the reagent "Ferrous-cyanide potassium" is very sensitive to changes in the alloy composition of silver alloys and makes it possible to establish the silver content with an accuracy of 5 %. The presence in silver alloys of such impurities as zinc, cadmium, nickel, gold, palladium and others increases the error in determining the fineness of silver and forms a different color and shade. It has been proven that testing of silver alloys on an assay stone with silver nitrate is effective only for the СрМ system. The presence of zinc in 925 sterling silver alloys visually increases the color intensity of the sediment, which indicates a higher overestimated fineness. It has been found that the identification of the content of precious alloys based on platinum for the presence of ligature components is carried out with a potassium iodide reagent at t=120 °C by the color and shade of the sediment. The procedure for using potassium iodide during testing of precious platinum-based alloys has been optimized

We present results of a study of hemispherical pins of manganese-zinc ferrite sliding against rigid disks composed of thin films of a sputtered cobalt-nickel-platinum alloy and carbon, with perfluoropolyether as the topical lubricant. The contact life, as marked by the total distance slid to the point at which the coefficient of friction increases rapidly over the steady state value, is much longer in air with 50 percent relative humidity than in dry air or vacuum. The wear debris generated in humid air is much finer and is enriched with cobalt on its surface. In dry air and vacuum, the debris is substantially larger than one micron and tends to be enriched with nickel on its surface. We present a hypothesis which explains the wear mechanisms in various operating environments.

AbstractThere are presents the internal recycling in anode furnace, in addition to mainly blister copper and converter copper. During the process there arise the two types of semi-finished products intended for further pyro metallurgical processing: anode copper and anode slag. The stream of liquid blister copper enters into the anode furnace treatment, in which the losses are recovered, e.g. copper, resulting from oxidation and reduction of sulfides, oxides and the oxidation of metallic compounds of lead, zinc and iron. In the liquid phase there are still gaseous states, which gives the inverse relationship relating to the solid phase, wherein the gases found an outlet in waste gas or steam. The results of chemical analysis apparently differ from each other, because crystallite placement, the matrix structure and the presence of other phases and earth elements are not compared, which can be regained in the process of electrorefining. One should not interpret negatively smaller proportion of copper in the alloy, since during the later part of the production more elements can be obtained, for example from sludge, such as platinum group metals and lanthanides. According to the research the quality of blister copper, to a large extent, present in the alloy phase to many other elements, which can be recovered.

An on-line multi-frequency electrical resistance tomography (mfERT) device with a melt-resistive sensor and noise reduction hardware has been proposed for crystalline phase imaging in high-temperature molten oxide. The melt-resistive sensor consists of eight electrodes made of platinum-rhodium (Pt-20mass%Rh) alloy covered by non-conductive aluminum oxide (Al2O3) to prevent an electrical short. The noise reduction hardware has been designed by two approaches: (1) total harmonic distortion (THD) for the robust multiplexer, and (2) a current injection frequency pair: low fL and high fH, for thermal noise compensation. THD is determined by a percentage evaluation of k-th harmonic distortions of ZnO at f=0.1~10,000 Hz. The fL and fH are determined by the thermal noise behavior estimation at different temperatures. At f <100 Hz, the THD percentage is relatively high and fluctuates; otherwise, THD dramatically declines, nearly reaching zero. At the determined fL≥ 10,000 Hz and fH≈ 1,000,000 Hz, thermal noise is significantly compensated. The on-line mfERT was tested in the experiments of a non-conductive Al2O3 rod dipped into conductive molten zinc-borate (60ZnO-40B2O3) at 1000~1200 °C. As a result, the on-line mfERT is able to reconstruct the Al2O3 rod inclusion images in the high-temperature fields with low error, ςfL, T = 5.99%, at 1000 °C, and an average error ⟨ςfL⟩ = 9.2%.

A gold solidus of Valentinian I, Emperor of Rome (A.D. 364-375) shown in Figure 1, and belonging to a private collection, was subjected to material and stylistic analysis, in order to ascertain about its authenticity. Due to the rarity of such a coin, only non-destructive analytical techniques were used, namely Scanning Electron Microscopy (SEM), Particle Induced X-ray Emission (PIXE), electrical resistivity and optical microscopy.Examination by SEM revealed that, in common with coins minted by this emperor, the solidus was die-struck as evidenced by the surface flow lines indicating metal movement under the dies (Figure 2). Wear traces presented an unorganized pattern. The coin was also examined for signs of stress-corrosion cracking but no evidence of this were found. The coin also shows traces of what appear to be soil residues; small quantities of these residues can also be seen in porosities in the coin face (arrow in Figure 3).Analysis by PIXE showed that the coin was made from an alloy of gold (97.9%), silver (2.0%) and copper (0.1%) (Figure 4). The high gold content is likely to be overestimated due to surface depletion of the silver and particularly the copper, which is caused by slight dissolution of these more reactive metals in the burial environment. Nevertheless, this effect is usually small and in agreement with other solidus from Valentiniano I. Also, the high gold content may lie behind the lack of stress-corrosion cracking.The presence of platinum group element (PGE) inclusions is, in some cases, indicative of alluvial gold provenience. Both, optical microscopy and PIXE, were used to detect them but it was not possible to identify their presence. Typically, the concentration of these elements is in the order of ppm, although for this specific period different values have been reported. Considering the experimental conditions used (2 MeV accelerated proton beam and a 50 μm Mylar foil in front of the X-ray detector) the limit of detection of the PIXE technique is close to the expected trace concentration. More energetic proton beam (>3MeV) or the use of specific filter for the X-ray signal in the low energy region, i.e. Zinc foil 75 μm thick, are the future experiments to be carried out in order to detect the presence of such characteristics PGE elements.In order to understand the presumable surface gold enrichment, electrical conductivity measurements were used. The values obtained (1.50-1.56)x1017 S/m show a lower conductivity as compared with the reference value for a 97% Au, 3% Ag alloy (3.54x1017 S/m), indicating that indeed the coin bulk has a lower gold content.As for the stylistic analysis, there is no sound agreement about the coin authenticity, but the tendency is to consider it a good one. The compositional and structural characterization of cultural heritage artefacts usually limit the number of available techniques to those considered as non-destructive and non-invasive, such the one presented in this work. This restriction also constricts and difficult the desired straight conclusions but, on the other hand, increase the multidisciplinary of the work, applying techniques usually dedicated to the material science characterization to cultural heritage.V. Corregidor acknowledges the funding support from the FCT-Ciência program. Financial support was also received through the PEST-OE/CTM-UI0084/2011 and PEST-OE/FIS/UI0275/2011 grants.

Long-term clinical observations show that widely used dentures made of metals and their alloys are not indifferent, cause a number of diseases of the oral mucosa, and have social and medical consequences in the form of intolerance to dental prosthesis materials[1,2]. Currently, ceramic materials, plastics, stainless steels, cobalt-chromium, silver-palladium alloys, gold-based alloys, platinum, etc. are used for orthopedic treatment. these alloys include the following metals: iron, chromium, Nickel, titanium, manganese, silicon, molybdenum, cobalt, palladium, zinc, silver, gold, etc. Signs of intolerance may occur when placing dentures and filling materials in the oral cavity. Intolerance to prosthetic materials can be caused by different reasons that have different mechanisms of pathology development. Solving problems with intolerance to dental materials in each patient requires analysis together with a dentist, an immunologist, and an immunological laboratory [1-4].

This study describes the development and characterization of novel high-temperature thermal storage media, based on inclusion of transition metal chlorides in the potassium-sodium chloride eutectic system, (K-Na)Cl (melting temperature of 657°C, latent heat of 278 J/g). At the melting temperature of (K-Na)Cl, infrared (IR) radiation can play a major role in the overall heat transfer process — 90 percent of spectral blackbody radiation falls in the range of 2 to 13 μm. The authors propose inclusion of small amounts (less than 0.2 wt %) of IR-active transition metal chlorides to increase radiative absorption and thereby enhance heat transfer rates. A new IR reflectance apparatus was developed to allow for determination of the spectral absorption coefficient of the newly formulated PCMs in the molten state. The apparatus consisted of an alumina crucible coated at the bottom with a reflective (platinum) or absorptive (graphite) surface, a heated ceramic crucible-holder, and a combination of zinc sulfide (ZnS) and zinc selenide (ZnSe) windows for containment of the salt and allowance of inert purge gas flow. Using this apparatus, IR spectra were obtained for various transition metal chloride additives in (K-Na)Cl, and improved infrared activity and radiative transfer properties were quantified. Further, thermophysical properties relevant to thermal energy storage (i.e., melting temperature, latent heat) are measured for the pure and additive-enhanced thermal storage medium.