医用真空高速轴承磨损失效分析

目的 从宏观和微观角度分析医用旋转阳极X射线管轴承部件磨损失效机制，从真空润滑角度进一步讨论医用X射线管旋转阳极真空轴承润滑剂。方法 采用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)及其能谱(EDS)，对使用后医用轴承组件金相组织、磨损形貌、磨损表面化学组成及其润滑介质进行表征。结果 2种轴承材料主要是SKH4或M50高速钢，相应润滑剂材料分别为MoS2和Pb-Cu合金。相对于Pb-Cu合金润滑剂，MoS2固体润滑膜容易产生磨屑和起尘。旋转阳极冷端轴承内外滚道磨损主要为磨粒磨损，滚动体磨损主要为磨粒磨损及疲劳失效。轴承部件表面局部可观察到电烧蚀和点蚀等现象。结论 医用旋转阳极X射线管轴承部件失效模式为典型磨损失效。

Wear Failure Analysis of High Speed and Vacuum Bearings for Medical Systems

This article reported the macroscopic and microscopic study on the wear-out failure of bearings and, further explored the state-of-art lubricants in the rotating anode X-ray tube for medical devices from the view of vacuum lubrication. The techniques including Optical Microscope (OM), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Electron Dispersive Spectrum (EDS) were adopted to characterize the worn morphology, chemical composition and lubricating medium over the bearings components. The results showed that the bearings in the rotating anode X-ray tube was made of SKH4 or M50 steel, while the lubricant materials were MoS2 and Pb-Cu alloy respectively. As compared with Pb-Cu alloy solid lubrication approach, MoS2 solid lubricant was prone to produce wear debris and dust phenomenon. It was found the main failure at the outer and inner raceway of the cold end of bearing resulted from abrasion, while predominant abrasive wear and fatigue symptoms occurred at the hot end of bearing. Moreover, electrical ablation and pitting corrosion were found at the localized regions of bearing components due to arc discharge at the contacting interface. The typical cause of the bearing failure in the rotating anode X-ray tube was attributed to wear, the developing trend of lubrication for the bearing components in the the rotating anode X-ray tube at present and in the coming long period of times was perceived.