Research On The Key Technologies Of High-Performance Bump Foil Bearings

The bump foil bearing is a kind of gas hydrodynamic lubrication bearing.Due to its remarkable advantages,it has been used in many high speed rotating devices.But when the foil bearing is running at the start and stop stages,the foil and the rotor encounter serious friction and wear problems.As a result the foil bearing has high starting torque and severe heat,whose service life is limited.In order to reduce the friction and wear of the foil bearing and improve its performance and service life,we study the key technologies of solid lubricant coating for bump foil bearings.In this paper,the WC-12 Co coatings were prepared by plasma spraying technology in disc specimens and bearing sleeves of foil bearings’ surfaces.Friction and wear properties of disc specimens were studied on a homemade pin disk friction and wear tester.The morphology and energy spectrum of friction and wear surface-cross section before and after were analyzed by SEM and EDS.The experiment platform for performance test of foil bearing was built.Friction and wear properties of the coatings used in the actual were explored by a bump foil bearing experiment platform.The microhardness,surface roughness,bonding strength and porosity of coatings were tested and analyzed.Contact stresses distribution of WC-12 Co coatings were studied by finite element analysis method and its influences on contact failure of coating were analyzed.In the end,the preparation and properties of composite coating were studied.The results show that the prepared WC-12 Co coating is significantly higher than its base in hardness.After polishing,its surface can meet the requirements of the surface finish of the foil bearing.The coating possesses good adhesive strength and relatively high density.The boundary of coating and substrate is clear and combined closely and its combination way is given priority to mechanical bonding,accompanied with a certain way of metallurgical bonding.Under the pin-disk friction and wear tester and the bump foil bearing experiment platform,the WC-12 Co coating showed very good resistance and anti-friction properties.The coating can reduce the friction and wear of bump foil bearing and improve its performance and service life.The finite element analysis shows that the coating failure mode is diversified under the combined effects of different main stress and shear stress.The stress is the main driving force of the coating failure.