Precious Metals have been used for centuries because of the aesthetic value and corrosion protection properties which they provide. The corrosion protection properties of precious metals is due to their nobility in the Electrochemical Activity Series. Since the start of the industrial revolution, these precious metals, along with Tin and Tin/Lead alloy, have been classed as the Engineering Metals because, by deposition, they have been used to engineer properties into many mass produced products. Since 2007 there is the new concept of Technology Metals which includes not only Precious Metals but also Rare Earth Elements (Yttrium and Lathanides) and Speciality Metals such as Gallium, Indium, Germanium and Thallium. These metals have become essential for the production of “high technology” devices and engineered systems particularly in the electronic and communication industry sectors.
Precious Metals have widespread applications in the aerospace, automotive, electronic and communication industries where they are used to engineer specific properties into products through a variety of productions processes. These metals are expensive and rare but are invaluable because of their intrinsic properties and high positive electrode potentials which means they are relatively inert to most aggressive environments. It is due to the high cost of these metals, that control of the chemical processes in which they are used is critical to the efficient and economic operations of the chemical surface treatment technology.
Gold Gold is considered practically indestructible, malleable, and completely recyclable while being virtually immune to the effects of air, water and oxygen. This unique combination of properties makes it a vital component in many medical, industrial and electrical applications. Gold is among the most electrically conductive of all metals and is also an excellent conductor of thermal energy or heat.
Silver Silver has the highest electrical and thermal conductivity of any metal. Other attractive properties of Silver are that it has the whitest colour, highest optical reflection and lowest contact resistance of any metal. Another unique property of Silver, which makes it ideal for high voltage contactors, is that it is the only metal which will not arc across the contacts.
Platinum The durability, hardness, high melting point, corrosion resistance and high temperature stability makes Platinum ideal for operating in extreme chemical environments. Platinum along with Iridium and Osmium is the most dense of all the metals, a property which contributes to their use in metallurgical applications.
Palladium Palladium has one of the lowest melting points of all the Platinum Group Metals (PGMs) and is also the least dense. Its main use in the chemical surface treatment is two fold, firstly it can be used as substitute for gold as an undercoat or as an alloy because it is cheaper then gold while still retaining the advantages of Gold. Palladium can also act as an effective barrier to diffusion between Copper and Gold.
Rhodium and Ruthenium
The main attraction of Rhodium is its brilliant white deposit, high wear and tarnish resistance, as well as its high and stable reflective properties. Ruthenium has been used as a substitute for Rhodium because it is significantly cheaper however more recently it is more common to use Ruthenium in decorative applications where it can be deposited as a black deposit.
We have worked on the installation and management of many Precious Metal Plating processes in start-up and Technology transfer situations.
Examples of some of the projects we have worked on include:
- Platinum Plating of High Temperature Turbine components.
- Silver Plating of Contacts.
- Gold Plating of Contacts for Electronic applications.
- Gold, Palladium, Rhodium, Ruthenium for corrosion protection and decorative applications.
