Optimization of Wind Turbine Spindle Bearing Gel-like Grease Performance at Extreme Temperatures

With the advancement of wind power technology towards larger-capacity and higher-power turbines, their main shaft bearings face significant lubrication challenges under extreme temperatures. In this study, seven modified greases were prepared by adding 0.5 wt.% of tungsten disulfide (WS₂), zinc sulfide (ZnS), and sulfurized isobutylene (T321). The concentration of all additives is given in weight percent (wt.%). Using a combined approach of friction and wear testing along with rheological analysis, this study systematically evaluated the tribological performance of the greases at high temperature (80 °C)-with the friction coefficient and wear scar diameter as key parameters-and their rheological properties across a wide temperature range (-20 °C to 80 °C), focusing primarily on shear stress and viscosity. All critical input parameters, including temperature, load, and shear rate, were precisely controlled and monitored using calibrated instruments. Results indicate that the WS₂ and T321 compounding system demonstrated optimal performance, achieving a low average coefficient of friction of 0.024 and an average wear scar diameter of only 0.367 mm. At the same time, the WS₂/T321 composite formulation exhibits excellent shear stability at high temperatures and good flow properties at low temperatures, demonstrating optimal viscosity-temperature characteristics. This study develops a promising grease formulation through multidimensional performance evaluation, offering key experimental support for designing high-performance wind turbine spindle bearing greases under high-temperature conditions.