滑动速度对单晶硅在不同接触尺度下磨损的影响

Effect of Sliding Velocity on the Wear Behavior of Monocrystalline Silicon under Various Contact Size

利用纳米划痕仪和液压伺服磨损试验机研究不同接触尺度下滑动速度对单晶硅磨损性能的影响。结果表明:单晶硅在不同接触尺度条件下表现出不同的损伤特征,同时滑动速度对其损伤有很大影响。微观单点接触条件下,单晶硅在低载下的损伤表现为凸起;速度越高,摩擦诱导的非晶层越薄,形成的凸结构越低。随着载荷增加,当接触压力高于单晶硅的硬度时,单晶硅的损伤逐渐转变为沟槽;滑动速度越高,接触区材料的加工硬化越剧烈,沟槽越浅。宏观多点接触条件下,较低的名义接触压力即会在单晶硅表面产生磨损,磨损过程中同时发生犁沟、疲劳和氧化磨损;滑动速度越高,单晶硅表面裂纹萌生得越多,产生的磨屑越细,磨损量越低。该研究结果有助于单晶硅超光滑表面制造的工艺改进以及硅基微机电系统的摩擦学优化设计。

The effect of sliding velocity on the wear behavior of monocrystalline silicon under various contact size is studied by nanoscratch and servo hydraulic dynamic test machine. It is found that both the contact size and sliding velocity played significant roles in the friction-induced surface damage of silicon. When the contact size is small enough to be considered as single-asperity contact, the surface damage of silicon exhibited the formation of hillock under low load. With the increase in the sliding velocity, the friction-induced amorphous layer became thinner and the height of hillock is lower. As the contact pressure increased above the hardness of silicon, the surface damage of silicon is identified as the generation of groove. The higher of the sliding velocity, the stronger the work-hardening of the contact area, and the shallower the groove. As a comparison, when the contact size is large enough to be considered as multi-asperity contact, the silicon surface may be worn even though the contact pressure is much lower than the hardness of silicon. During the wear process, both plough, fatigue and oxidation wear occurre simultaneously. With the increase in the sliding velocity, more cracks are initiated, tinier wear debris is generated, and less wear volume is observed. The results may not only help the improvement of the nanofabrication technique of silicon, but also optimize the tribological design of microelectromechanical system.