Environmental Atmosphere On The Arc Caused Of C/C Composites And Current-carrying Friction And Wear Properties

A series of tests on arc rate, friction coefficient and wear rate under different conditions had been carried out on a high-speed friction and wear testing machine with a pin-on-disc configuration with C/C composites as pin sample and QCr0.5as disc sample, which simulated the working conditions of current collectors sliding against overhead contact wires. The effects of speed, current and load on arc rate, friction coefficient and wear rate of C/C composites/QCr0.5couples were investigated using single-factor tests. The arc rate and friction and wear properties of C/C composites also were investigated under different environmental atmosphere. The microstructure and phase composition of worn surface were examined using scanning electron microscope(SEM) and energy dispersion spectrum analyzer (EDS), respectively. The influences mechanism of different atmosphere and test conditions on the arc rate and wear rate and friction coefficient was explained.The results show that, at air atmosphere, the arc rate of C/C composites/QCr0.5couples increase with the increasing of current and speed, and the arc rate increases at first and then decreases with the increasing of the load, the arc rate is minimum, when the load is70N. The wear rate of C/C composites increases with the increase of the current and speed, has a decreasing trend with the increase of the load, especially when the current is more than60A, the wear rate increases almost proportionally with the increasing continually of current. And the friction coefficient increases with the increasing of the load and the velocity. The wear rate of C/C composites reaches peak—about0.041mg/m when the speed increased to30m/s under the condition of120A.In a nitrogen atmosphere, the change rule of the arc rate and friction and wear properties of C/C composites is accord with air atmosphere. Comparison study find that the friction coefficient in a nitrogen atmosphere is higher than in an air atmosphere, and the wear rate in a nitrogen atmosphere are lower than in an air atmosphere.The SEM micrograph of the worn surface of C/C composites at different conditions, it can be seen arc erosion pits, ploughs and a number of wear particles on the worn surface. And the EDX analysis of the worn surface found that there is Cu, O peaks in addition to C peak on the contact surface of worn pin specimen, this shows that is because that oxidation wear and material transfer are also the wear mechanisms accompanied by arc erosion, abrasive wear and adhesive wear. And the EDX analysis of the worn surface in a nitrogen atmosphere found that there is Cu, C peaks on the worn surface of C/C composites, because that the test is carried out without oxygen atmosphere.