水轮发电机碳刷/集电环无载流与载流干滑动摩擦磨损性能研究

Tribological Performance of Carbon Brush/Collector Ring for Hydroelectric Generator under Dry Sliding Condition with Current-Carrying and without Current-Carrying

针对水轮发电机碳刷/集电环摩擦副磨损严重、打火和励磁电流不稳等现象.在对常用碳刷(D172、E468e)磨损原因及影响因素分析的基础上,采用碳刷/GCr15钢球配副在Anton Paar Tribometer多功能摩擦磨损试验机上,研究干滑动条件下载荷、速度及电流密度对碳刷/GCr15钢球配副摩擦学性能的影响.结果表明:碳刷/集电环摩擦副在载流与无载流时的摩擦磨损性能相差较大.无载流时,D172和E468e两碳刷的磨损率均随载荷的增大呈现先减小后增大的趋势,在达到最小值时出现大转折,两碳刷磨损率变化趋势呈“U”字型.无载流时D172碳刷磨损率远低于E468e,载流时则情况相反.D172碳刷无载流时磨损机理以磨粒磨损为主并伴有轻微黏着磨损,载流时碳刷除发生磨粒磨损、黏着磨损外还伴有氧化磨损.E468e碳刷在载流前后均为磨粒磨损.D172碳刷摩擦系数整体呈增大趋势,而E468e碳刷摩擦系数先缓慢增大随后逐渐减小,电流对D172碳刷摩擦系数的影响比E468e碳刷更明显.

In order to reveal the cause of the severe wear,sparking and unstable excitation current of the carbon brush/collector ring on hydroelectric generator,the carbon brush/GCr15 ball pair was used to simulate its contact and friction condition on the Anton Paar Tribometer multi-functional friction and wear tester.Then the effects of load,speed and current density on the tribological properties of the carbon brushes(D172,E468 e)under the dry sliding condition with current-carrying and without current-carrying were analyzed.The results show that the tribological performance of the carbon brushes with current-carrying was quite different from that without current-carrying.Without currentcarrying,the wear rates of D172 and E468 e carbon brushes decreased first and then increased with the increase of load.When the minimum value was reached,a large turning point occurred,so that the change trend of the wear rate of the two carbon brushes was"U"shape.Without current-carrying,the wear rate of the D172 carbon brush was much lower than that of the E468 e,while opposite result was obtained for current-carrying condition.Without current-carrying,the wear mechanism of D172 carbon brush was mainly abrasive wear accompanied by mild adhesive wear.With currentcarrying,in addition to abrasive wear and adhesive wear,the carbon brush was accompanied by oxidative wear.The wear mechanism of E468 e carbon brushes was abrasive wear with and without current-carrying.The friction coefficient of D172 carbon brush increased,while the friction coefficient of E468 e carbon brush increased slowly and then gradually decreased.The effect of current on the friction coefficient was obvious for D172 carbon brush but not obvious for E468 e carbon brush.