核主泵水润滑推力轴承试验的磨损颗粒研究

摘要

某核主泵水润滑推力轴承在试验浸银石墨瓦时，在类似热瞬态工况时出现异常振动及噪声，拆机发现石墨推力瓦和推力盘硬化层表面均出现较严重磨损，且石墨推力瓦出现局部剥落。采用化学、光学、 X 射线衍射、扫描电镜、透射电镜、电子探针等方法研究水润滑轴承试验的磨损颗粒相结构、形貌、成分、组织和磨损表面特征；明确热瞬态时不锈钢推力盘硬化层与石墨推力瓦的摩擦磨损形式和过程，得出水润滑推力轴承已经进入边界润滑状态，局部发生干摩擦的结论；提出一些改进建议，如将水润滑轴承瓦面材料改为碳素纤维复合材料以增加抗磨性能，改善瓦面形状以减少热变形，增加接触曲面硬化层以控制高应力曲面接触的微动磨损。%When testing the silver impregnated graphite pad of the water-lubricated thrust bearing for a nuclear main pump,unusual vibration and noise occur at transient thermal like working conditions,and serious wear are observed on the surfaces of both graphite pad and thrust plate after the thrust bearing disassembling,and even some partial peeling occur on local region on graphite pad surface.The wear debris was analyzed by using a number of techniques including chemical,op-tical,XRD,SEM-EDS,TEM,and EPMA to study their phase structure,morphology,composition and microstructure as well as worn surface features,respectively.The wear behavior and process of the graphite pad and Stellite hard-faced thrust plate in thermal transient were identified,and the conclusion was drawn that the water-lubricated thrust bearing is in a condition of boundary lubrication state,and local dry friction was taken place.It is suggested that,using carbon fiber composite in-stead of silver impregnated graphite to improve the wear performance of thrust bearing,optimizing the surface configuration of pad to reduce thermal deformation during friction, and increasing surface hardening layer on the supporting contact faces to control the fretting wear due to the high stress contact among the bearing components.