The Effect of Lubricant Composition on White Etching Crack Failures


White etching cracks (WECs) are the dominant mode of failure for wind turbine gearbox bearings. These failures are characterized by subsurface initiation and local region of microstructural alterations adjacent to the crack faces. The definitive cause of WECs within the field is unknown, because of this laboratory replication has proved difficult. At a benchtop scale, specific lubricant formulations referred to as “bad reference oils” (BROs) are often employed to aid in the formation of WECs; however, exactly how these lubricants induce WECs is unknown. The present work intends to elucidate how these lubricants facilitate the formation of WECs by systematically varying the additives which are found in BROs and studying the effect that these additive combinations have on time until failure, as well as tribofilm development. It was found that the lubricant containing Zinc dialkyldithiophosphate alone led to the formation of WECs sooner than any lubricant studied. It was also documented that a lubricants frictional characteristics play a more dominant role than the tribofilm characteristics.

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This work is supported by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy, Wind Energy Technology Office under Contract No. DE-AC02-06CH11357, as well as funding from Afton Chemical Limited. The authors are grateful to DOE Project Managers Mr. Michael Derby and Mr. Brad Ring for their support and encouragement. The authors would also like to acknowledge the assistance provided by our colleagues at Argonne National Laboratory’s Tribology Section, especially Dr. Maria De La Cinta Lorenzo Martin for her assistance with electron microscopy and Dr. Oyelayo Ajayi for his helpful discussion on metallurgy. Use of the Center for Nanoscale Materials an Office of Science user facility was supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-06CH11357.

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Gould, B., Demas, N.G., Pollard, G. et al. The Effect of Lubricant Composition on White Etching Crack Failures. Tribol Lett 67, 7 (2019).

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  • White etching cracks
  • Bearing failures
  • Microstructural alterations
  • Premature fatigue