Friction and Wear Performance of Candidate Surface Treatments for Wind Turbine Gearbox Bearings in High Slip Contacts

Ring-on-ring rolling/sliding contact tests were conducted to evaluate the impact of ground, black oxided, isotropically finished (ES20), and tungsten carbide-incorporated amorphous hydrocarbon coated surfaces (ES322) on friction and wear in high slip contacts relevant to wind turbine gearbox bearings. The testing was performed in three phases, including Stribeck testing, adhesive wear testing, and cyclic acceleration testing. Results indicated that neither black oxide treatment nor ES20 had long-term adhesive wear protection benefits. However, ES20 exhibited the lowest traction coefficients in boundary lubrication during run-in as compared to the other test surfaces. Only the contacts containing the ES322 hard-coated surface consistently survived the harshest slip and boundary lubrication conditions.