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The process was invented in 1874 by Emil Wohlwill. This electrochemical process involves using a cast gold ingot, often called a doré bar, of 95%+ gold to serve as an anode. Lower percentages of gold in the anode will interfere with the reaction, especially when the contaminating metal is silver or one of the platinum group elements.
Invented by Emil Wohlwill in 1874, the Wohlwill process produces the highest purity gold (99.999%). It is an electrolytic process using pure gold for the cathode (or titanium as a starter cathode) and chloroauric acid (gold chloride-hydrochloric acid) as the electrolyte; this is made by dissolving gold with chlorine gas in the presence of ...
This process is limited to very thin coatings, since the reaction stops after the substrate has been completely covered. Nevertheless, it has some important applications, such as the electroless nickel immersion gold (ENIG) process used to obtain gold-plated electrical contacts on printed circuit boards.
The gold is typically applied by quick immersion in a solution containing gold salts. This process is known in the industry as electroless nickel immersion gold (ENIG). A variant of this process adds a thin layer of electroless palladium over the nickel, a process known by the acronym ENEPIG. [19]
Electroless nickel immersion gold (ENIG or ENi/IAu), also known as immersion gold (Au), chemical Ni/Au or soft gold, is a metal plating process used in the manufacture of printed circuit boards (PCBs), to avoid oxidation and improve the solderability of copper contacts and plated through-holes.
Electroforming process Electroforming is a metal forming process in which parts are fabricated through electrodeposition on a model, known in the industry as a mandrel . Conductive (metallic) mandrels are treated to create a mechanical parting layer, or are chemically passivated to limit electroform adhesion to the mandrel and thereby allow its ...
Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. The process is called anodizing because the part to be treated forms the anode electrode of an electrolytic cell.
The video describes the electrolytic process as it is occurring on Captain Kidd's Cannon, which is on display and currently undergoing the electrolytic process. An electrolytic process is the use of electrolysis industrially to refine metals or compounds at a high purity and low cost. Some examples are the Hall-Héroult process [1] used for ...