Tribological Properties Of Pure Carbon Strip Based On Pantograph/Catenary Vibration During Current-Carrying Sliding

Pantograph is the only way for the electrical locomotives to get energy from the traction power supply system.Tribological properties of the strip decided the capacity and quality of the current transmission between the pantograph and the contact wire.Vibration leaded to unstable contact of rubbing with electric conduction,which became one of the incentives leading to pantograph/catenary system incidents.However,most of the present tribological studies were based on static contact.Therefore,tribological studies of the pure carbon strip subjected to dynamic contact force had important theory significance and project value for the safe and steady operation of electric locomotives.The main contents in this paper are as follows:1.The dynamic mold of pantograph/catenary system was founded,by which dynamic contact force between the pantograph and contact wire was calculated.All the results were compared with EN50318,which verified the reasonableness and correctness of the mold in this paper.The calculated dynamic contact force was finally used to provide theoretical basis for the following tribological studies with current-carrying sliding under vibration.2.Tribological experiments were carried out on a home-made pin-on-disk tribometer(HST-100),with which sine waves were loaded from pin(pure carbon)to disk(QCr0.5)to simulate the dynamic contact in pantograph/catenary system.Loading accuracy of the tribometer with current subjected to dynamic contact force was tested to verify its flexible loading capacities.3.Tribological experiments were designed based on previous dynamic study.Firstly,coupling working condition experiments were completed with amplitude(B)and frequency(f)increased simultaneously.Secondly,amplitude experiments were carried out with varying B and frequency experiments were carried out with varying f.Thirdly,tests were conducted with random B and f.Finally,tribological properties of the pure carbon strip subjected to dynamic contact force with current-carrying sliding were discussed.4.Arcing intensity and arcing morphology during the experiments were captured.Arcing properties of the pure carbon strip affected by dynamic contact force were summarized at last.Surface morphology of the strips,chemical composition of the wear debris and ablation products were detected by SEM,EDS,3D Surface Profiler and XPS.Tribological experiments in coupling working condition showed that mechanical wear leaded the wear mechanism at lower velocity.And arc erosion became the dominant wear mechanism at faster velocity.What was special,oxidation film was generated at 80km/h which leaded to the best friction and wear properties.Arc discharges of the pure carbon strip fluctuated periodically according to the vibration of dynamic contact force.It was the dominant factor which leaded to the properties evolution of the strip.Arc discharges induced current distortion,which destroyed the consistency and stability of the current between the pantograph and the catenary.Tribological experiments with varying amplitude showed that contact stability in pantograph/catenary system was weakened by the increasing B.It leaded to the raise of arcing rate which resulted in the decrease of current-carrying quality.Arc erosion deteriorated surface quality of the pure carbon strip,leaded to the production and extension of cracks,induced material spalling.Therefore,friction and wear properties of the strip were decreased.On the other hand,tribological experiments with varying frequency showed that the increasing f at 80km/h contributed to the generation of oxidation film,which improved the surface quality of the worn surface.Friction and wear properties of the pure carbon strip were increased efficiently.The dynamic model of pantograph/catenary system with finite element method was founded in this paper.Dynamic contact force between pantograph and contact wire at different velocity was calculated,which was then used to study the tribological properties of the pure carbon strip in tribological experiments.At last,the friction and wear properties,current-carrying quality and arc discharges were summarized according to the test results.This paper revealed the relationship of dynamic contact force and material damage with properties evolution.It is expected to enrich the tribological theory of pantograph/catenary system,provide theoretical support for the improvement and application of pantograph/catenary materials and improve the safety of the locomotives.