Platinum Metals Review - Volume 40, Issue 2, 1996

Several new, more highly corrosion resistant titanium alloys containing a nominal 0.1 weight per cent of ruthenium have been developed and evaluated for industrial service in corrosive environments. These improved ruthenium-enhanced α, α-β and β titanium alloys are lower in cost than the corresponding palladium-containing titanium alloys, and offer essentially the same corrosion performance in dilute reducing acids and hot brine environments. The titanium-0.1 ruthenium binary alloys can be cost effectively substituted for traditional titanium-palladium alloys and should represent a more attractive alternative to nickel-chromium-molybdenum alloys in hot, acidic brine applications. The corrosion database that has been established for the higher strength ruthenium-enhanced α-β and β titanium alloys in high temperature sweet and sour brines provides the basis for their selection for applications in the chemical process, oil/gas production, offshore and geothermal energy industries.

Screen printed thick film technology is recognised as an inexpensive and effective means for the production of superconductors which have potential applications in the electronics and microwave device industries. Additions of the platinum group metals have been made to superconducting thick films of YBa2Cu3O7-δ, and these have shown significant improvements, relative to melt processed films, in both their superconducting and physical properties, particularly in their critical current densities. A possible mechanism to explain the improvements is discussed.

The concluding part of this paper on the use of ruthenium(II) and osmium(II) polypyridyl complexes, as molecular sized terminal subunits that are linked together by polyyne bridges functioning as molecular girders to retain the stereochemical rigidity, deals with the process of electron transfer between the subunits and considers the benefits conferred by the use of polyyne bridges. The ruthenium and osmium complexes have properties which aid the selective promotion of an electron from the metal to the bridging ligand, together with amenable absorption and emission spectral profiles, and facile oxidation-reduction processes. This makes them promising candidates for vectorial electron transfer. Future work to extend the lengths of the linkages, to ensure unidirectional and longrange electron tunnelling, and to anchor the wires to supports is discussed. These are the necessary requirements for the development of molecular wiring made from these materials for future use with molecular-scale electronic devices.

Since the introduction of palladium-gold catchment gauzes for the recovery of the platinum lost from the catalyst gauzes used in the manufacture of nitric acid, the mechanism by which these high palladium content alloys catch and recover the platinum has been of interest to both researchers and manufacturers, alike. Using analyses of the surface chemical species which form on palladium, both in flowing oxygen and during the ammonia oxidation reaction, this paper describes how the surface of the palladium, at temperatures above 800°C, is a multilayer structure with the bright palladium metal surface being covered by a thin layer of palladium metal vapour and then by a layer of palladium oxide vapour. The mechanism of the platinum recovery is related to the surface state of the palladium, and the high recovery rate by the palladium alloy catchment gauze is attributed to this unique multilayer structure and to the ability of palladium to reduce platinum oxide. Damage to either the surface multilayer structure or the oxidation characteristics of palladium decreases the platinum recovery rate. Thus, catchment gauzes made from palladium alloys containing high concentrations of base metal solutes, such as nickel, cannot be expected to have such a high platinum recovery rate.