单晶硅滑动磨损性能及其相变研究

考察了单晶硅在室温和低接触应力条件下的摩擦磨损行为随速度的变化情况．结果表明，单晶硅的摩擦系数和磨损率随滑动速度的提高而呈现降低趋势；单品硅在低速、短滑动时间下的磨损表面形貌特征以微断裂为主，并伴有一定程度的塑性变形;随着滑动时间的延长，塑性变形特征逐渐减弱，塑性变形同具有金属延性特征的p—Sn(简称si—II)相密切相关，Si—II在滑动过程中可转变为体心立方结构(简称Si-III)、斜方六面体结构(简称Si—XII)和非晶硅相;在高速条件下，单晶硅磨损表面呈现微断裂和较弱的塑性变形特征；尽管通过Raman分析证实磨损表面存在si—III相，但其对磨损机制的影响有待于进一步研究．

Sliding Wear Behavior and Phase Transformation of Single Crystal Silicon

The friction and wear behavior of single crystal silicon as a function of velocity at room temperature and low contact stress was studied. Thus the sliding tests of Si-Si_3N_4 pair were conducted on a UMT-2MT test rig, in ambient air and under unlubricated condition. The morphologies and chemical features of the worn silicon surfaces under various sliding conditions were analyzed by means of scanning electron microscopy and Raman spectroscopy. It was found that the friction coefficient and the wear rate of the single crystal silicon decreased with increasing sliding velocity. Friction-induced phase transformation of silicon was involved during the sliding process, which allowed the generation of Si-III, Si-XII, and amorphous silicon on the worn silicon surface. Such a kind of friction-induced phase transformation of silicon was closely dependent on the sliding conditions and had great effect on the wear mechanisms of the silicon. Namely, the worn surface of the single crystal silicon under a smaller sliding velocity and duration was characterized by micro-fracture and had a moderate plasticity, while the micro-fracture and plasticity on the worn surface tended to be decreased at a prolonged sliding duration. The plasticity of the worn silicon surface was attributed to the friction-induced phase transformation of silicon. Although Si-III phase was detected by Raman spectroscopy on the worn silicon surface at a larger sliding velocity, it needed further work to clarify the factors affecting the wear mechanism of single crystal silicon in this case.