Research on Brake Friction Pairs Matching under Current-Carrying Conditions

Objective To address the issue in maglev vehicle pads, where under energized conditions, due to the effects of resistance heat and arc heat, the temperature of the contact surface of copper-based powder metallurgy brake pads in maglev vehicles increases significantly compared to non-energized states, resulting in a decrease in the brake pad friction coefficient and an increase in the wear rate. Method By comprehensively using the OLYMPUS-DSX100 digital stereo microscope, the JSM-6610 scanning electron microscope, and the OXFORD X-MAX50 energy spectrometer, the wear amount, friction coefficient, and wear morphology characteristics of the brake pads are systematically analyzed. Through the current-carrying friction wear test bench, the influence of the friction pair surface Rockwell hardness（51.8 HRC to ≥50 HRC after hardfacing） on the brake pad performance is investigated, revealing the regulatory mechanisms of current intensity（0-50 A） and temperature on the tribological behavior. Result ＆ Conclusion Upon introduction of the current, the resistance heat and arc heat cause the contact surface temperature rise, resulting in material softening, reduced bonding strength, and a 2-3 times increase in wear rate compared to the no-current condition and 15%-20% decrease in friction coefficient. The wear-resistant hardfacing layer can increase the Rockwell hardness of the friction pair to above 50 HRC. and carbides formation can effectively inhibits arc erosion, reducing the brake pad wear rate by 50% and stabilizing the friction coefficient at 0.367 5. The worn morphology analysis shows that the hardfacing treatment can reduce the furrows and the accumulation of abrasive debris, improve the surface layering phenomenon, and achieve long-term matching of the friction pair. This achievement provides a key technical support for extending the service life of brake pads and tracks, reducing operation and maintenance costs（estimated to be reduced by 20%～30%） and ensuring the safe operation of maglev vehicles.