In some wind turbine drivetrain, wind gearbox bearings may be due to premature cracking, spalling or irregular white corrosion cracking (WEC's). WEC polishing and etching microscopic means changing the appearance of the steel structure. Several positions bearing failure in the wind gearbox design,chumacera
planetary bearings, intermediate shaft and the high speed shaft were found.
Because of extensive discussions WEC fault occurs within the wind power industry, and is independent of the wind turbine manufacturer and the gearbox manufacturer and supplier of bearings, as well as universities and independent body to investigate. Many current hypotheses have focused on issues related to the surface,stainless steel bearings
such as hydrogen permeation and mixed with underground and surface operations or purely stress / tribomechanical development interaction. For further information on the hypothesis that the root cause of the failure of WEC, see . http://www.szr-bearing.com/
According to literature from the ongoing investigation and information, different mechanisms can reduce WEC failures, such as risk contribution:
Tribology and reduce chemical attack  ( "passive")
Reduce hydrogen diffusion into the bearing steel  ( "passive")
Corrosion protection 
Raceway microstructure stabilization .
Black oxide can be said to protect the bearing assembly from the failure mechanism. In the following, several laboratory tests and investigations revealed the advantages of black oxide.