Alloys & Industrial Crucibles
Because of their hardness, high melting points and high temperature stability PGMs are the perfect coating for industrial crucibles where high temperatures are necessary to produce chemicals and synthetics with the utmost efficiency.
The high temperature stability, melting points and corrosion resistance of platinum, rhodium, and iridium and their alloys allow for higher temperatures to be achieved in crucibles, a key factor in any chemical process.
The "nobility" of PGMs is also crucial. High purity conditions are required for these processes and PGMs' high temperature stability means that they do not contaminate the products being fabricated.
PGMs can have a quite remarkable effect on other metals. For example, titanium's corrosion resistance is boosted a hundred times by the addition of just 0.1 per cent of ruthenium. This gives titanium an even more effective and durable role in aerospace and marine applications where resistance to extremes of temperature and salt water is crucial.
Applications for alloys between the PGMs include fuel cells, industrial crucibles and tools, and jewellery.
Products produced in such ways include: crystals, glass, and glass fibre.
A variety of crystals are grown by a number of different techniques. The principal method of growth involves the pulling of a single crystal from a pool of molten salts contained in the crucible. Due to its high melting point and resistance to chemical attack, iridium is the preferred material for crucibles used in the production of high purity single crystals of various metal oxides.
Laser technology relies upon high-quality crystals and their optical and electronic qualities and has a range of applications.
In industry its uses include: drilling, cutting, engraving, welding, sensing and measurement. In medicine: eyesight correction, cosmetic procedures and non-invasive surgery are amongst its applications.
Platinum and rhodium are used in the fabrication of vessels that hold, channel and form the high-quality molten glass that is used, for example, for Liquid Crystal Displays (LCDs) and plasma screens. With their unique properties, they are able to withstand the harsh conditions under which the raw materials for the glass are melted, including the heat of usually 1650 degrees Celsius.
Unlike base metal alloys, platinum and platinum alloys do not react to glass, nor do they oxidize or scale at high temperatures, thereby maintaining the purity of the glass.
Rhodium is alloyed with platinum in various proportions from 5 per cent rhodium up to 30 per cent rhodium. The addition of rhodium increases the strength of platinum alloy equipment and extends its life.
(Picture: Row of plasma screens)
The versatility of glass fibre finds its use in a range of applications.
These are just a few of its uses:
- as a reinforcer for plastic and concrete;
- in insulation for buildings;
- in the hulls of ships, fuselages of aircraft and walls of petrol tankers,
- and in everyday products such as ladders and fishing rods.
Glass fibre optics is used in telecommunications applications where they have greater capacity, transmission speed and efficiency and are cheaper to maintain than other cables.
It is produced in crucibles made of PGMs and their alloys which are resistant to the high temperature and corrosiveness of molten glass.