Development Of High Speed Electric-tribometer And Researches On Tribo-electric Behaviors Of Strip Materials

Supported by the National Natural Science Foundation of China (No. 50432020) and theNational 973 project (2007CB607603) and due to the systematic characteristics of tribo-electficfriction pairs, great needs for researches on tribo-electric behaviors of materials of pantographstrips are becoming more and more urgently with the development of running speed and loadingelectric current of locomotives. Based on the materials used for locomotives electric supplysystem of high speed railway, the researches are carded out on following aspects in this paper.1, the special tribo-electdc tester with high sliding speed and electric current was developed,which mail working parameters are, current density up to 2.5 A/mm~2, the sliding speed 100 m/s,the load over 500 N (3.2 MPa) and the pulsant strike pressure within 20 N. This testersuccessfully simulates the tribological and electric properties of strip materials.2, By using the above tester, study on tdbological properties and carrying currentperformances of copper-base powder metallurgy material and metal impregnation carbonmaterial are carded out. The results show that the copper-base powder metallurgy materialsposses the best wear resistance under the condition of 0.45 A/mm~2, 0.37 MPa and 40 m/s and themetal impregnation carbon materials show the best wear resistance under the condition of 0.45A/mm~2, 0.37 MPa and 50 m/s which are both accordance with the running conditions of trainswhich use copper-base powder metallurgy strip and metal impregnation carbon strip.3, After systematical researches on wear resistance, reducing friction, stabilities of carryingcurrent and friction coefficient of copper-base powder metallurgy material and metalimpregnation carbon material, the following conclusions are obtained:(1), the copper-base powder metallurgy material coupled with QCr 0.5 can only be used underconditions of current less than 0.45 A/mm~2, pressure under 0.45 MPa and sliding speed less than40-60 m/s for the aim of low wear rate. The conditions in detail are that sliding speed is less 60m/s when current is 0.3 A/mm~2 and pressure is 0.37 MPa, sliding speed is less 40 m/s whencurrent is 0.45 A/mm~2 and pressure is 0.37 MPa. (2), the metal impregnation carbon material only can be used under conditions of current lessthan 0.45 A/mm~2, pressure under 0.55 MPa and sliding speed less than 50 m/s for the aim of lowwear rate. The conditions in detail are that sliding speed can reach 70 m/s when current is 0.3A/mm~2 and pressure is 0.37 MPa, sliding speed can reach 50 m/s when current is 0.45 A/mm~2and pressure is 0.37 MPa, sliding speed can reach 40 m/s when current is 0.6 A/mm~2 andpressure is 0.37 MPa.(3), wear rate of metal impregnation carbon material is lower than that of copper-base powdermetallurgy material by 54.8%-79.8% which indicates that wear resistance of former is muchbetter than that of the latter. The stability of carrying current of metal impregnation carbonmaterial is better than that of metallurgy material.(4), friction coefficient of metal impregnation carbon material is higher than that of copper-basepowder metallurgy material by 14.4%-150% which indicates that anti-friction property offormer is worse than that of latter. The stability of sliding contact of metal impregnation carbonmaterial is worse than that of copper-base powder metallurgy material.4, Due to the fact that effects of tribological parameters on the process of wear with current aremore complicated than those of common sliding process, parameters of stabilities of carryingcurrent and friction coefficient are introduced in this paper to evaluate properties of couple withcurrent.