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Deformation and fracture behaviour of cold drawing iridium wire under tension at room temperature is examined. High purity polycrystalline iridium was manufactured using pyrometallurgical technology. During the initial stage of cold rolling, iridium wire has its usual grain structure and exhibits brittle deformation behaviour: poor plasticity and brittle transgranular fracture (BTF). However, the wire begins demonstrating high plasticity including necking in spite of the brittle fracture mode when the lamellar structure has been formed in iridium during cold drawing.
Platinum-based alloys are being developed for high-temperature applications with the aim of replacing some of the currently used nickel-based superalloys (NBSAs) and benchmark alloy, PM2000. The platinum-based superalloys have a similar structure to the NBSAs and can potentially be used at higher temperatures and in more aggressive environments because platinum is more chemically inert and has a higher melting point. In this paper, the recent progress in research and development of platinum-based superalloys is overviewed. Firstly, the composition optimisation and structural design of platinum-base superalloys are introduced. The structural characteristics, mechanical properties, oxidation resistance and corrosion behaviour of platinum-aluminium ternary, quaternary and multiple superalloys are summarised. Finally, directions for further research and application of platinum-based superalloys are analysed and prospected.
Here, we report the frequency dependent ultrasonic attenuation of monometallic gold and bimetallic gold/platinum based aqueous nanofluids (NFs). The as-synthesised bimetallic NFs (BMNFs) revealed less resistance to ultrasonic waves compared to the monometallic NFs. Thermal conductivity of both NFs taken at different concentrations revealed substantial conductivity improvement when compared to the base fluid, although gold/platinum showed lesser improvement compared to gold. Characterisation of the as-synthesised nanoparticles (NPs) and fluids was carried out with X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). The distinct two-phase bimetallic nature of gold/platinum, its two plasmonic band optical absorption features and the spherical morphology of the particles were shown. The findings were correlated with the observed thermal and ultrasonic behaviour and proper rationalisation is provided. It was revealed that the comparatively lesser thermal conductivity of gold/platinum had direct implication on its attenuation property. The findings could have important repercussions in both industrial applications and in the mechanistic approach towards the field of ultrasonic attenuation in NFs.
Ruthenium tablets with mean grain size of ~4–5 μm were prepared by vacuum hot pressing (VHP), and tablets with maximum density of 12.2 g cm–3 were obtained with sintering time of 2 h. X-ray diffraction (XRD) revealed that there was a texture change with sintering time. The microstructure of the ruthenium tablets was observed by electron backscatter diffraction (EBSD) and field emission scanning electron microscopy (FSEM). The microstructure evolution of ruthenium with sintering time is discussed.
It is known that platinum-rhodium thermocouples exhibit mass loss when in the presence of oxygen at high temperatures due to the formation of volatile oxides of platinum and rhodium. The mass losses of platinum, Pt-6%Rh and Pt-30%Rh wires, commonly used for thermocouples, were considered in this paper to characterise the mass loss of wires of the three compositions due to formation and evaporation of the oxides PtO2 and RhO2 under the conditions that would be seen by thermocouples used at high temperature. For the tests, the wires were placed in thin alumina tubes to emulate the thermocouple format, and the measurements were performed in air at a temperature of 1324°C, i.e. with oxygen partial pressure of 21.3 kPa. It was found that the mass loss of the three wires increases linearly with elapsed time, consistent with other investigations, up to an elapsed time of about 150 h, but after that, a marked acceleration of the mass loss is observed. Remarkably, previous high precision studies have shown that a crossover after about 150 h at 1324°C is also observed in the thermoelectric drift of a wide range of platinum-rhodium thermocouples, and the current results are compared with those studies. The mass loss was greatest for Pt-30%Rh, followed by Pt6%Rh, then platinum.
Johnson Matthey is keen to encourage research into future applications of platinum group metals (pgms). As a global leader in sustainable technologies, our focus is on clean air, clean energy, healthcare and the efficient use of the planet’s natural resources – and on the fundamental properties of pgms on which these applications depend. Johnson Matthey’s commitment to progress in platinum...
Introduction Platinum group metals (pgms) have widespread applications as functional materials in many different industries. The applications range from catalytic surfaces or particles, sensors, biomedical imaging or drug delivery systems and thermocouples up to jewellery items that we use for special moments of our life. The pgms are used as solid bulk materials, powders, thin films,...
Electrical resistivity values for both the solid and liquid phases of the platinum group metals (pgms) rhodium and iridium are evaluated. In particular improved values are obtained for the liquid phases of these metals.
In the 2014 review (1) discovery circumstances for 85Ru and 86Ru were referenced only in the form of a preprint but have now been reported in the open literature (2). For the most recently discovered isotopes the discovery years for both 128Rh and 90Pd are the manuscript dates of the given references whilst for 125Ru, 130Pd and 131Pd the common discovery year corresponds to the original...
Since the 2018 review (1) one new light isotope of mass 165 (2) and four new heavy isotopes of masses 209 to 212 (3) have been identified for platinum (Table I). The heavy isotopes are only identified as being ‘particle stable’ – that is resistant to proton or neutron decay but all are expected to decay by beta decay in which an electron and anti-electron neutrino are emitted when a...
This paper provides a database of mechanical properties for most of the commercially available platinum alloys currently in use for jewellery purposes. The alloys were tested for mechanical properties through tensile and microhardness testing in the as-cast and hot isostatically pressed conditions. Microstructural characterisations were performed using scanning electron microscopy (SEM).
Electrical resistivity values for both the solid and liquid phases of the platinum group metals (pgms) palladium and platinum are evaluated. In particular improved values are obtained for the liquid phases of these metals. Previous reviews on electrical resistivity which included evaluations for the pgms included those of Meaden (1), Bass (2), Savitskii et al. (3) and Binkele and Brunen (4) as well as individual reviews by Matula (5) on palladium and White (6) on platinum.
We review developments in the study of the stability of platinum-iridium standard weights, in particular the kilogram prototypes manufactured from alloy supplied by Johnson Matthey in the 1880s that still stand at the heart of the International System of Units (abbreviated SI from the French: Système international d’unités). The SI has long since moved on from length standards based on physical artefacts fabricated from this alloy, but the SI unit of mass is still defined in this way, as the mass of a real physical object. The stability of these reference masses has been a concern since the 1930s, with mass loss or gain at the surface being the principal concern. In recent years X-ray photoelectron spectroscopy (XPS) has been particularly valuable in elucidating the types of contamination present and the mechanism by which contamination takes place. While direct studies on the International Prototype Kilogram are understandably difficult, at Newcastle University we have examined the surfaces of six Pt mass standards also manufactured in the mid-19th century, using XPS to identify contamination chemically. XPS shows a significant quantity of mercury on the surfaces of all six. The most likely source of Hg vapour is the accidental breakage of thermometers and barometers, and the mechanism of contamination may be similar to the poisoning of platinum group metal (pgm) catalysts by Hg, an effect known for almost a century.
The use of various sintering technologies, allied to suitable powder metallurgy, has long been the subject of discussion within the global jewellery manufacturing community. This exciting, once theoretical and experimental technology is now undoubtedly a practical application suitable for the jewellery industry. All parts of the jewellery industry supply and value chains, and especially design and manufacturing, now need to become aware very quickly of just how unsettling and disruptive this technology introduction has the potential to become. This paper will offer various viewpoints that consider not only the technology and its application to jewellery manufacture but will also consider the new design potentials of the technology to the jewellery industry. It will also briefly consider how that design potential is being taught to future generations of jewellery designers at the Birmingham School of Jewellery. We shall also discuss in some detail the economics of and potential for new and different business models that this technological paradigm might offer the jewellery industry.
This review briefly describes the vacuum electrostatic levitation furnace developed by JAXA and the associated non-contact techniques used to measure the density, the surface tension and the viscosity of materials. The paper then presents a summary of the data taken with this facility in the equilibrium liquid and non-equilibrium liquid phases for the six platinum group metals (pgms): platinum, palladium, rhodium, iridium, ruthenium and osmium over wide temperature ranges that include undercooled and superheated phases. The presented data (density, surface tension and viscosity of Pt, Rh, Ir, Ru and Os and density of Pd) are compared with literature values.
Having established that osmium is the densest metal at room temperature the question arises as to whether it is always the densest metal. It is shown here that at ambient pressure osmium is the densest metal at all temperatures, although there is an ambiguity below 150 K. At room temperature iridium becomes the densest metal above a pressure of 2.98 GPa, at which point the densities of the two metals are equal at 22,750 kg m–3.
In this paper, changes in the mechanical properties of Pd-5Ni alloy are analysed after recrystallisation annealing in order to determine the optimal conditions for a thermomechanical processing regime for this alloy. The temperature and annealing time were varied and the resulting changes in hardness, tensile strength, relative elongation and proof strength were monitored. By using the simplex-lattice method and analysing experimental data, a fourth degree mathematical model-regression polynomial was defined and isolines of changes in the mechanical properties of the investigated alloys were designed depending on the conditions of heat treatment after rolling.
The changes in phase state, electrical properties and microhardness of copper-55 at% palladium alloy samples with different initial states (as-quenched and deformed via severe plastic deformation (SPD)) were studied during isothermal annealing. Ordered B2-phase formation in the disordered (A1) matrix was found to occur at a significantly higher temperature than is indicated in the generally accepted phase diagram of the Cu-Pd system. Corresponding electrical resistivity is also lower than reported elsewhere for alloys of similar compositions, at ρ = (27.67 ± 0.04) × 10–8 Ωm, making this the lowest resistivity yet reported for a Cu-Pd alloy with 55 at% Pd.
In the 2012 review (1) the isotope 209Pt was included based on a claim to its discovery by Kurcewiz et al. which was reported in a preprint (2). However when the actual paper was published (3) it was considered that the evidence for 209Pt was unsatisfactory and it was no longer included. Therefore the number of known isotopes for platinum has been amended in Table I. In addition one...
The principal possibility of processing the industrial poor collective concentrates of platinum group metals (pgms) using a hydrocarbonyl technology with the selective concentration of pgms from poor multicomponent chloride and chloride-sulfate solutions with the subsequent production of pure pgms is shown.