40Cr/石墨关节轴承摩擦学性能及磨损机理研究

Study on Tribological Properties and Wear Mechanism of 40Cr/Graphite Spherical Plain Bearings

针对某核电阻尼器用自润滑关节轴承不允许使用聚四氟乙烯(PTFE)和铜材质零件的需求,研制了一种40Cr/石墨关节轴承。为了研究该液压阻尼器摆动工况对关节轴承的影响,首先通过自研的关节轴承负载模拟台对该关节轴承在10 kN的径向载荷、1 Hz的摆动频率和±5°的摆幅下进行了50000次摆动摩擦实验;然后利用实验过程中记录的摩擦力矩、径向磨损量和摩擦温度分析了石墨与40Cr长时间对摩的摩擦学性能变化;最后借助双束扫描电子显微镜所获取的石墨内圈微观形貌探讨了实验工况下该关节轴承的磨损机理。实验结果表明:在磨合阶段,磨损量、摩擦系数和温度呈现大幅提高,然后过渡到稳定磨损阶段,在稳定磨损阶段的后期,均呈现小幅上升趋势;轴承在整个摆动磨损过程中运动状态良好,无卡死现象,实验结束后轴承径向磨损量为112μm、内圈质量减少0.02 g;石墨内圈在不同接触位置上呈现不同的磨损机理,核心承压区主要为磨粒磨损、疲劳磨损和黏着磨损,非核心承压区主要为磨粒磨损。

A 40Cr/graphite spherical plain bearing was developed to meet the requirement that PTFE and copper parts were not allowed to be used in self-lubricating spherical plain bearings for a nuclear power damper.In order to study the influence of the swing condition of the hydraulic damper on the spherical plain bearing,50000 swing friction tests were carried out on the spherical plain bearing under the radial load of 10 kN,the swing frequency of 1 Hz and the swing amplitude of±5°by using the self-developed spherical plain bearing load simulator.Then the tribological properties of graphite and 40Cr were analyzed by using the friction torque,radial wear and friction temperature recorded during the test.Finally,the wear mechanism of the spherical plain bearing under test conditions was discussed by the microstructure of graphite inner ring obtained by double beam scanning electron microscope.The results showed that the wear quantity,friction coefficient and temperature increased greatly in the running-in stage,and then transition to the stable wear stage.At the later stage of the stable wear stage,they all showed a slight upward trend.During the whole swing wear process,the bearing moved well without jamming.After the test,the radial wear amount of graphite inner ring was 112μm,and the mass decreased by 0.02 g.The wear mechanism of graphite inner ring is different at different contact positions.The core bearing area is mainly abrasive wear,fatigue wear and adhesive wear,while the non-core bearing area is mainly abrasive wear.