What Does Red Plague Mean?
Red plague has several meanings or uses across various fields. In the context of corrosion, red plague refers to the galvanic corrosion found on silver-plated copper wires that is often associated with high-resistance/corroded wiring.
Red plague has been observed in the industry since 1957. The occurrence rate has been described as an "occasional but persistent phenomenon." Mechanical damage exposing copper to water has been thought to be the primary cause of red plague.
Red plague is also known as cuprous oxide corrosion.
Corrosionpedia Explains Red Plague
Red plague is a type of electrochemical corrosion—a copper-silver galvanic cell forms and the copper acts as a sacrificial anode. In suitable conditions, the corrosion can proceed rather quickly and lead to total circuit failure.
When silver is plated over copper, copper corrosion can be an accelerated through galvanic action at pinholes or breaks in the silver plating. This corrosion is known as "red plague" and is identifiable by the presence of a brown-red powder deposit on the exposed copper.
In theory, red plague can only occur if the silver/copper interface is exposed to the atmosphere where moisture and oxygen are present. Additional, as-yet-unidentified agents may also play a role. If left unchecked, red plague advances to cupric oxide, which is black in color.
P. L. Anthony and O. M. Brown established in 1965 that red plague originates at breaks in the silver plating of copper wire strands in the presence of moisture and oxygen. The environmental test system artificially promotes red-plague corrosion under controlled laboratory conditions as a result of galvanic corrosion of the copper conductor core.
Environmental factors must be controlled in order to avoid red plague.