Flexible Contact Condition Effects On The Tribological Properties Under Electric Current

The tests were carried out on the HST-100 tribo-tester after the transformation of the load device with C/C composite, which simulated working conditions of the pantograph-wire system used in the electric railway. Influence of pressure ampitude ,frequency and speed on the friction and wear properties of carbon/carbon composites was studied under flexible contact condition. With the help of SEM, EDS and XRD, the morphologies of frication surface of pin were examined, in order to study the tribological mechanism under different parameters.According to the experiments, ampitude of contact pressure have significant impact on carrying-current quality and wear. The effect are significant with greater ampitude. Therefore, the contact pressure must be maintained constant in operation of motorcycles.The experimental results show that the friction coefficient and wear rise, and the carrying-current quality got better with increase of pressure frequency. Proper increases of frequency with fixed speed, that reduce the span of railway catenary will improve the carrying-current quality.The friction coefficient and wear rise with increase of velocity. The current-carrying efficiency and current-carrying stability have little change with low velocity. When the velocity was greater than 25m/s, current-carrying efficiency and current-carrying stability reduced drastically with the increase of velocity, and carrying-current quality was declined.Combination of the images of the worn surface, the wear surface under fixed pressure was more smooth than the wear surface with flexible contact condition.The surface was more and more rougher, large area of holes and the ablation traces appear with the increase of ampitude. The surface was rough under low frequency, a thick smooth friction film was formed along the sliding direction with the increase of frequency.With low velocity, the surface had signs of wear particles and smooth. With high velocity, the worn surface had a large number of empty and bare fiber and rough, the wear mechanism was changed from lower velocity to the higher velocity.With the arc erosion, sediment carbon and carbon fiber in C/C composite were gasified and formed carbon film on superficial. The worn surface was mainly composed of C phase and a little Cu phase adhesion over the friction disc. The C/C composite were mostly destroyed by arc erosion because of oxidation wear and material transfer.