Bearing failures account for a significant share of the operational economical losses in hydropower plants. In Kaplan turbines, the most critical components are the self-lubricating polymer composite bearings used for regulation of the guide vanes and the turbine blades as they operate at high loads, low sliding speeds and small oscillatory movements. Reducing the sliding wear and friction of these bearings would offer a positive impact on both the economy and environment including longer useful life, lower operational costs and higher efficiency.
In this study, influence of counter surface roughness and orientation on the tribological behavior of bearing materials used in hydropower applications are investigated using a linear reciprocating block-on-block configuration under high pressure and low sliding speed. Surface roughness was measured using white light interferometry. SEM and EDS analysis were used to investigate the polymer surfaces and the transfer film formation.
Results from this study indicates that too smooth surfaces result in higher friction and wear of the counter surface while rougher surfaces have a negative effect on the wear of the polymers. It can be concluded that counter surface topography has a significant influence on the tribological behavior of these bearings and the effect differs between materials.