Abstract
At present, main bearings in wind turbines are equipped with rolling bearings without exception. Sliding bearings instead can offer a number of advantages, including easier maintenance and extended lifetime. While conventional manufacturing processes for large sliding bearings face their limits regarding processable materials, thermal spraying can provide an effective alternative to meet the requirements by applying coating systems on the bearing surfaces. Within this study a wide range of different feedstock materials based on standard bearing materials and common wear and friction reducing coating systems are investigated. The coatings are tested on tribometers based on the load distribution within the main bearing at critical operating conditions of the wind turbine gained from a validated simulation model. A tribological methodology is developed to investigate the application related properties of the thermally sprayed coatings. The effects of load and geometry of the counter body on the friction and wear behavior of the coatings are investigated using a pin-on-disc and a modified high-load ring-on-disc tribometer. The presented results provide a major contribution to the purpose of identifying an appropriate coating system to meet the requirements of slow-moving and highly loaded sliding bearings.
