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

## TL;DR

This study improves wind turbine bearing grease performance at extreme temperatures by testing modified formulations with additives like tungsten disulfide and sulfurized isobutylene.

## Contribution

A novel WS2/T321 composite grease formulation is developed, showing superior tribological and rheological properties under extreme temperatures.

## Key findings

- The WS2/T321 composite achieved a low average friction coefficient of 0.024 and a wear scar diameter of 0.367 mm.
- The formulation exhibits excellent shear stability at high temperatures and good flow properties at low temperatures.
- The study provides experimental support for designing high-performance greases for wind turbine bearings.

## Abstract

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.