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Pure Gold is besides Platinum the chemically most stable of all precious metals. In its pure form it is not very suitable for use as a contact material in electromechanical devices because of its tendency to stick and cold-weld at even low contact forces. In addition it is not hard or strong enough to resist mechanical wear and exhibits high material losses under electrical arcing loads (<xr id="tab:Contact_and_Switching_Properties_of_Gold_and_Gold_Alloys"/>)<!--(Tab. 2.4)-->. This limits its use in form of thin electroplated or vacuum deposited layers.
For most electrical contact applications, gold alloys are used. Depending on the alloying metal, the melting is performed either under a reducing atmosphere or in a vacuum. The choice of alloying metals depends on the intended use of the resulting contact material. The binary Au alloys with typically < 10 wt% of other precious metals such as Pt, Pd, Ag or non-precious metals like Ni, Co and Cu are the more commonly used ones (<xr id="tab:Physical Properties of Gold and Gold-Alloys"/>)<!--(Tab. 2.2)-->.
