Effect of as-ground surface and the BALINIT® C and Nb–S coatings on contact fatigue damage in gears

V. Moorthy, B.A. Shaw
Tribology International, Volume 51, July 2012

Abstract

The influence of as-ground surface and the BALINIT^® C and Nb–S coatings on contact fatigue damage have been investigated using testing of case-carburised S156 steel helical gears. The micro-surface features on the as-ground gear flank tend to initiate micro-pitting. In BALINIT^® C coated gears, the surface irregularities are removed by polishing effect resulting in small scale initiation of micro-pitting at the interface between polished and unpolished regions. In Nb–S coated gears, the coating tends to penetrate and fill-up the surface micro-valleys and hence showed only scattered micro-pitting. The Nb–S coated gears did not produce any tooth profile loss whilst the BALINIT^® C coated gears produced profile loss. However, both BALINIT^® C and Nb–S coated gears show enhanced contact fatigue performance.

Additional Information:

This research work had been carried out at Design Unit, Mechanical and Systems Engineering, Newcastle University, UK.  Design Unit specialises in gearbox technology including gear design, stress analysis, fatigue testing, gear metrology, material characterisation and failure analysis. Excellent facilities are available for gear metrology, gear manufacture, instrumentation for in-service troubleshooting, materials analysis and for evaluating the contact and bending fatigue strength of gears and bearings. Design Unit actively participates in research projects with academic and industrial partners around the world where it brings a rich experience in the design, testing and analysis of gears for broad ranging applications including transport, defence and energy sectors. Design Unit is very happy to interact and give advice on various aspects of gear technology. Further information can be obtained at www.ncl.ac.uk/gears.

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