Wear of mica under aqueous environments: Direct observation of defect nucleation by AFM
Wear of mica under aqueous environments: Direct observation of defect nucleation by AFM
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DOI：
10.1021/la048842p
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发表时间：
2005-01-18
期刊：
影响因子：
3.9
通讯作者：
Batteas, JD
中科院分区：
文献类型：
--
作者：
Helt, JM;Batteas, JD
滑动接触表面缺陷的产生是材料最终磨损的催化剂。在这里，白云母云母的磨损已被调查，在水环境下使用原子力显微镜（AFM）。通过同时获得地形，摩擦。和受控pH条件下的粘附数据，可以直接观察到总磨损之前原子尺度上的缺陷成核。发现成核最初表现为由于应力诱导的摩擦化学键断裂引起的表面充电，因为OH-使表面终止Si-O-Si或Si-O-Al键断裂。由于表面键被连续地分裂，缺陷的集合（例如，Si-OH/Al-OH和Si-O-）对晶格重构（从近似5.2埃到近似3埃）有贡献。如在AFM形貌和摩擦力显微照片中观察到的。在晶格重构之后，云母表面材料的位移/提取增强，产生容易辨别的深度范围从2埃到10埃的磨损疤痕。环境OH-浓度深刻地影响了这一系列导致磨损的事件的效力，并通过在相同的负载和扫描条件下调节pH值加速或抑制磨损来说明。
The generation of defects at surfaces in sliding contacts is the catalyst for the eventual wear of the materials. Here, the wear of muscovite mica has been investigated under aqueous environments using atomic force microscopy (AFM). Through concomitant acquisition of topography, friction. and adhesion data under controlled pH conditions, defect nucleation on the atomic scale prior to gross wear may be directly observed. Nucleation is found to present itself initially as charging of the surface due to stress- induced tribochemical bond scission as OH- breaks open the surface terminating Si-O-Si or Si-O-Al bonds. As the surface bonds are continually cleaved, an ensemble of defects (e.g., Si-OH/Al-OH and Si-O-) contribute to a crystal lattice reconstruction (from similar to5.2 to similar to3 Angstrom). as observed in AFM topographic and frictional force micrographs. Following lattice restructuring, displacement/abstraction of mica surface materials ensues, yielding readily discernible wear scars ranging from similar to 2 to 10 Angstrom in depth. The environmental OH- concentration profoundly affects the efficacy of this sequence of events leading to wear and is illustrated by the acceleration or inhibition of wear with adjustment of pH under identical load and scan conditions.