Surface Nano-structured Coating for Improved Performance of Axial Piston Pumps (SNAPP) Final Report

The project starts from the consideration that most of the power losses in a hydraulic pump come from the friction between parts in relative motion. The need to provide, especially at low rotational speed, hydrodynamic lift, causes power losses, in terms of volumetric and mechanical efficiency, due to the contrasting need to increase leakage to provide lubrication and to keep a minimum clearance in meatus to limit the volumetric losses. The potential for application of special surface treatments have been exploited in pioneering works in the past, trying different surface finishing or adding ceramic or heterogeneous metallic layers. The potential of structured coatings at nanoscale, with super-hydrophobic and oleophobic characteristics, has never been exploited. The project aims at investigating the potential of surface nano-coating of the piston slippers surface, in order to improve the overall efficiency map of the component through a significant reduction in fluid friction losses. In the following pages the results of the project will be showed for every working package.