Platinum Metals Review - Volume 31, Issue 2, 1987

Platinum and its alloys have long been accepted as essential materials for the fabrication of equipment used in the glass industry. However the superior mechanical properties of the zirconia grain stabilised materials developed by Johnson Matthey have led to their successful utilisation for many of the most demanding applications; for others conventional platinum group metals and alloys are still preferred and both types of material are considered here.

Cladding base metals with platinum or platinum alloys offers certain technical and economic advantages. In an earlier paper the mechanical properties of the metals to be joined were discussed. In this second paper it is shown that interdiffusion of the two materials being joined together must be considered, and that if the partners have different diffusion coefficients difficulties can result during later production stages. This is especially true if voids form in the diffusion zone due to the Kirkendall effect. This effect is particularly pronounced when copper alloys are used as the base metal, however it can be avoided either by using nickel-rich alloys or by incorporating an electrodeposited intermediate nickel layer of suitable thickness.

A new type of two-dimensional metallic conductor, based upon a palladium dithiolene complex, has been shown to possess a novel structure involving short S–S contacts in two orthogonal directions, resulting in it having metallic properties down to 40K under high pressure. Studies of compounds of this type may lead to the development of materials for use in a chemical computer and a major programme in this area, to be known as the Molecular Electronics Research Initiative, is to be launched by the British government.

Platinum-based alloys find many applications in both high and low temperature industrial environments and are particularly suited to operation under corrosive aqueous and high temperature gaseous conditions. A wide variety of alloys exist which have been specifically designed for these purposes and in many cases they contain one or more non-platinum group metal. Although this situation is quite acceptable, there remains a fundamental need for systematic investigation of the basic properties and constitution of platinum group metal alloys. Such a foundation in materials technology generally leads to an understanding of materials behaviour and provides guidance in designing new alloys with improved properties for existing and future applications. This review features the work which has been done on ternary and higher order platinum group metal alloys and provides access to important data.

Astronomy and navigation depend to a large extent on the ability to measure angular displacements with a high degree of accuracy, and since early times instrument makers have sought to improve the usefulness of their products by innovation. Shortly after ingots of malleable platinum and palladium became available commercially in England it was realised that these new metals had properties which were superior to those of silver, upon which the scales used for measuring angles were then engraved. The use made of platinum and palladium by one London firm of instrument makers in the first half of the nineteenth century is considered here.