What Does Crevice Corrosion Index Mean?
The crevice corrosion index is a means of estimating the susceptibility of a material to crevice corrosion. Crevice corrosion is a type of metal deterioration that can occur in a gap between two different materials. Although both metals may be resistant to corrosion, they can still be subject to crevice corrosion due to the electrochemical mechanisms that the crevice enables.
Corrosionpedia Explains Crevice Corrosion Index
The crevice corrosion index can be helpful when determining which material to select when there is a risk of small gaps between two materials. This is especially true if the materials are subject to a chloride rich environment.
The crevice size needs to be just right for crevice corrosion to occur. It needs to be wide enough so that a solution can enter the crevice, but narrow enough so that the solution that has entered the crevice is not allowed to flow freely and exit the crevice. In the case of a chloride rich environment, this lack of flow allows chlorides to gather in the crevice and initiate the corrosion.