Gold is a precious metal used in many everyday applications, such as jewelry and electronics. It is commonly alloyed with other metals, such as silver, to change its color or properties.
Copper & Zinc: These additives are commonly added to white gold and yellow gold karats for various reasons. They deoxidize, lighten the color, reduce hardening on air cooling, lower the melting point, and improve fluidity and tensile strength.
The presence of copper in silver and nickel alloys makes them more corrosion resistant than those without copper. The addition of zinc also increases the toughness and abrasion resistance of these alloys, as well as their electrical and thermal conductivity.
An alternative to the Miller process for refining gold-silver alloys that contain more than 30% gold is the aqua regia leaching method, which uses an acid solution to open up the metal, and then oxidize it to the chloride state. The results are usually very satisfactory.
A bimetallic catalyst containing copper and gold is an attractive catalytic material for various industrial processes. However, the use of this type of alloy has been relatively little studied, and there is a need to better understand its chemical properties in order to optimize the performance of these materials.
Gold and its alloys are susceptible to corrosion and tarnish. These effects may lead to the loss of their luster and value. This paper describes the different ways in which these corrosion effects occur and illustrates them with examples of South American gold alloys from Colombia and Panama.