电极性对地铁第三轨摩擦磨损行为的影响

Effects of the Polarity on the Friction and Wear of the Third Rail in Subway

利用改进的销-盘摩擦磨损试验机,试验研究电极性对地铁钢铝复合式第三轨与受电靴摩擦副之间的载流摩擦磨损特性,测量摩擦系数、摩擦表面温升及摩擦副磨损体积损失随电流和电极性变化的规律,采用EDX和XRD等手段测量摩擦副磨损表面的化学成分,分析摩擦副在不同电极性下的载流摩擦磨损机制。结果表明:随着电流的增大,摩擦副接触区温度升高,接触面软化,切向力降低,摩擦系数下降,摩擦副磨损体积损失增大;受电靴接电源正极时摩擦副的氧化程度和磨损体积损失比接负极时严重;载流摩擦副之间的表面过渡层中的水在电场作用下分解成氢氧根离子和氧离子,氢氧根离子流向正极并析出氧气,高温阳极氧化的作用降低了接正极受电靴摩擦副材料表层的结合强度,加剧了材料的磨损,从而改变了摩擦副的摩擦磨损特性。

The effects of polarity on the friction and wear characteristics of aluminum-stainless steel composite third rail and the friction pair of collector shoe with electrical current were studied by the modified pin-on-disc friction and wear tester. The friction coefficient, the temperature rise of friction surface and the wear volume loss of friction pair were measured under different electric current density and polarity. The chemical constituents of the worn surfaces were measured by means of energy dispersive X-ray spectroscopy （EDX） and X-ray diffraction （XRD）, and the wear mechanisms with electric current under different polarity were analyzed. The results show that with the increasing of electric current, the temperature at the contact area of friction pair increases, the contact surface softens, then the tangent force and the friction coefficient decrease, the wear volume loss of friction pair increases. The oxidation degree and the wear volume losses of the friction pair are larger when the collector shoe is connected with positive pole than that connected with the negative pole. Water molecules in the surface transition layer between the current-car- rying friction pairs decompose into hydroxide and oxygen ions under the influence of electric field. The hy- droxide ions migrate to the anode then generate oxygen. The anodic oxidation reaction in high temperature weakens the bond between the grains in the surface layer of positive friction part, which aggravates the wear of material, then changes the friction and wear characteristics of friction pair.