载荷和滑动速度对块体镁基非晶合金干摩擦性能的影响

目的以制备的Mg_(59.5)Cu_(22.9)Ag_(6.6)Gd_(11)块体镁基非晶合金为基础,探索法向载荷和滑动速度影响镁基非晶合金干摩擦行为的规律和机制,为进一步研究镁基非晶合金提供实验依据。方法采用UMT-2多功能摩擦磨损机,改变法向载荷和滑动速度的大小,进行摩擦磨损实验。通过白光干涉轮廓仪测出磨损轨迹的宽度和深度,再根据公式计算出磨损体积和磨损率。利用扫描电镜和EDS能谱分析磨损轨迹,揭示非晶合金的磨损机制。结果随着载荷的增加,磨损率先减小后稳定,摩擦系数略有减小。随着滑动速度的增加,磨损率先减小后增大,在相对滑动速度为120 mm/s时出现最小值。载荷小于20 N时,磨痕表面布满犁沟和小颗粒状磨屑;载荷大于20 N时,磨痕表面出现层叠状非均匀塑性变形层,对磨球表面转移膜粘连明显。滑动速度低时,磨痕表面布满犁沟,随着速度的增加,先是软化均匀流变,接着出现熔化、剥落。结论块体非晶镁基合金在低载荷下以磨粒磨损为主,还伴随着氧化、少量的粘着;载荷大于20 N时,变为粘着磨损为主。低滑动速度下以磨粒磨损为主,当滑动速度为180 mm/s时,试样表面熔化失效,磨损方式为剥落和磨粒磨损的综合。

Effects of Load and Sliding Velocity on Dry Friction Properties of Mg-based Bulk Metallic Glass

The work aims to study rule and mechanism of influence of normal load and speed on dry friction behavior by using Mg59.5Cu22.9Ag6.6Gd11 Mg-based bulk metallic glass (BMG), and provide an experimental basis for further studies of BMG. Friction and wear experiments were performed by changing normal load and sliding speed with UMT-2 multifunctional friction and wear machine. Width and depth of wear tracks were measured with white light interferometry, and wear volume and wear rate were calculated according to formula. Wear tracks were analyzed with scanning electron microscopy and EDS energy spectrum, and wear mechanism of BMG was exposed. With the increase of load, the wear rate first decreased and then remained stable, and friction coefficient decreased slightly. With the increase of sliding speed, the wear rate first decreased and then increased, and the minimum value appeared at the relative sliding speed of 120 mm/s. When the load was less than 20 N, the grinding crack surface was covered with furrows and small granular debris. When the load was greater than 20 N, inhomogeneous overlapped plastic deformation layer appeared on the surface of BMG, and the friction ball head was apparently glued with transferred thick and sticky film. When the sliding speed was low, the grinding crack surface was covered with furrows. As the speed increased, the surface was subject to softening and uniform rheology, followed by melting and spalling at low load. Wear mode of the BMG is abrasive wear accompanied by oxidation and slight adhesion at low load, and mainly adhesive wear at the load of over 20 N. The wear mode is mainly abrasive wear at low sliding speed, and combined spalling and abrasive wear (melting failure) at the sliding speed of 180 mm/s.