Surface engineering in wind turbine tribology

Abstract

Infantile failures of rolling bearings in large-scale wind turbines have limited the reliability of these clean energy generation systems. The major components of a modular wind turbine nacelle include the mainshaft that connects the blade assembly to the gearbox, and the generator. Bearing failures in the components have been attributed to fretting (or false brinelling), smearing, electric arc damage and surface- and subsurface-initiated fatigue. Two surface engineering technologies have been widely employed to address the infantile failures of the rolling bearings: black oxide surface treatments and a W-DLC coating. The specific rolling bearing applications where these technologies are being used in large-scale wind turbines and their effectiveness at mitigating the various tribological issues that cause the infantile bearing failures are described in this paper.