Definition - What does Bridging mean?
Bridging refers to a connection created between two dissimilar metals so that an electrical circuit is connected for galvanic corrosion to take place. It is mostly demonstrated by using an electrolyte in battery cells so that the different metals can obtain anodic and cathodic points.
It is used to reduce the corrosion rate of a base metal by allowing one metal—high in the galvanic series—to become an anode. The corrosion prevention is achieved by allowing one metal to have a high rate of corrosion.
Corrosionpedia explains Bridging
In normal circumstances, the rate of individual metals exposed to seawater and conditions that lead to corrosion depends on the galvanic number of the metal. Galvanic corrosion occurs when two dissimilar metals are in contact and exposed to conditions that lead to corrosion.
In this case, reducing the rate of corrosion of one metal alloy is achieved by the introduction of a metal that is at the top of the galvanic series. By creating a short circuit between the metals, bridging creates a flow of current. Corrosion will occur on the “active” metal and the “noble” metal will remain protected.
Corrosion prevention can be added by providing a coating around the “noble” metal and in other cases using dehumidifiers if bridging is not needed in a situation where the metals in connection are important.