Fretting wear

Fretting wear (also know as fretting corrosion) is due to a lack of lubrication between two oscillating or vibrating surfaces. Contact between the micro-moving faces causes the contacting asperities to break away creating a metal debris. The micro-sized particles oxidize in the presence of oxygen and become harder than the underlaying metal, causing an acceleration of the wear process and as the hard particles further abrade the the metal surfaces in a never ending cycle. Fretting corrosion can usually be detected by the presence of a reddish brown rust-like dry residue with steel components, and a black residue with aluminum components.

Diagram of fretting wear/corrosion