Full Text for Volume 49 Number 1 (January 2005)

 

This issue contains the following:

Investigating New Platinum Alloys for Jewellery Applications
Platinum alloys used in jewellery need to be sufficiently soft for easy working by the manufacturer, but not too soft to lower their wear resistance. A good compromise would be to use a soft alloy during jewellery production which could then be hardened so the final finished properties were improved. Work to identify new platinum alloys suitable for hardening has been undertaken at Mintek in South Africa by T. Biggs, S. S. Taylor and E. van der Lingen. They describe properties of Pt alloys with different alloying additions. A Pt-2 wt.% Ti alloy was considered to have potential in jewellery fabrication.

 

Thermal Conductivity of Pt Alloys Increases with Temperature
Parameters that affect the thermal conductivity of various platinum alloys at high temperatures are surveyed by Yoshihiro Terada, Tokyo Institute of Technology, Japan, and Kenji Ohkubo and Tetsuo Mohri, Hokkaido University, Japan, using the laser flash method. The thermal conductivity was found to be predominantly determined by composition and temperature and is little affected by work hardening. Adding a solute decreases the thermal conductivity –  the conductivity-composition relationship has a sharp maximum at pure Pt. From 300 to 1100 K, the thermal conductivity of Pt alloys increases with increasing temperature. The temperature coefficient is inversely correlated with the thermal conductivity.

 

Fuel Cells – Science and Technology 2004
Donald S. Cameron reviews the second in a series of biannual European fuel cell meetings entitled “Scientific Advances in Fuel Cells Systems”. This was held in Munich, in October 2004. These meetings take place in alternate years to the Grove Symposium, giving a balance between the scientific and commercial aspects of the technology. Significant developments in modelling and other experimental techniques reported on will permit more advanced studies of the complex interrelated characteristics of fuel cells, stacks and their systems. This should result in faster development. This meeting was notable for the increased attendance by academics.

 

Electrochemistry of Proton Conducting Membrane Fuel Cells
The Fourth International Symposium on Proton Conducting Membrane Fuel Cells held in Honolulu, in October 2004, is reviewed by Sarah C. Ball, Johnson Matthey Technology Centre, U.K. For commercial success the polymer electrolyte membrane fuel cell needs more active catalysts and cheaper, more durable, membranes. In addition, an improved understanding of the deterioration mechanisms of the membrane electrode assemblies is required. New work on all these aspects is reported.

 

Ruthenium Indenylidene Complexes
Ruthenium indenylidene complexes are robust and efficient pre-catalysts for olefin metathesis reactions, specifically for RCM of substituted linear dienes, acyclic diene metathesis of a,w-dienes, enyne metathesis and ROMP of cycloolefins. Reactions of these complexes are reviewed by Valerian Dragutan and Ileana Dragutan (Institute of Organic Chemistry, Romanian Academy, Romania) and Francis Verpoort (Ghent University, Belgium). The complexes allow reactions not promoted by earlier Ru catalysts, such as the synthesis of tri- and tetrasubstituted cycloalkenes, and RCM involving highly substituted dienes. The activity and stability of these pre-catalysts can be finely tuned by adjusting both steric and electronic effects in the metal coordination sphere by selecting appropriate ancillary ligands. This class of Ru complexes is accessible, has enhanced activity and good stability, and could enhance the scope and utility of current metathesis catalysts.

 

Platinum Group Minerals in Eastern Brazil
Brazil does not have working platinum mines, nor even large reserves of the platinum metals, but there is Pt in Brazil. Professor Nelson Angeli from the University of São Paulo State (UNESP), Brazil, describes four massifs in the eastern Brazilian states of Minas Gerais and Ceará, where Pt is found. Three of these massifs contain concentrations of platinum group minerals, and gold, associated with the chromitite rock found there. The fourth massif, in Minas Gerais, has alluvial deposits of platinum group elements, at the Bom Sucesso occurrence.

 

PGM Literature and Patent Selection
The issue also contains a selection of abstracts based on recently published patent and scientific literature.

 

Final Analysis – Safeguarding Thermocouple Performance
Roger Wilkinson, Johnson Matthey Noble Metals, U.K., describes how open circuits can develop in platinum/rhodium thermocouple limbs. This is Part III in his series of short articles on looking after thermocouples to extend their service life.

Susan V. Ashton
Editor

Contact
The Editor, Platinum Metals Review, Johnson Matthey PLC, Orchard Road, Royston, Hertfordshire SG8 5HE, United Kingdom; Fax +44 (0) 1763 256359; Email jmpmr@matthey.com

Please click below for PDF file of: