Materials Science Program, Department of Mechanical Engineering, University of Wisconsin, Madison, Wisconsin 53706, USA.
ACS Nano. 2010 Jul 27;4(7):3763-72. doi: 10.1021/nn100246g.
Atomic force microscopy (AFM) is a powerful tool for studying tribology (adhesion, friction, and lubrication) at the nanoscale and is emerging as a critical tool for nanomanufacturing. However, nanoscale wear is a key limitation of conventional AFM probes that are made of silicon and silicon nitride (SiNx). Here we present a method for systematically quantifying tip wear, which consists of sequential contact-mode AFM scans on ultrananocrystalline diamond surfaces with intermittent measurements of the tip properties using blind reconstruction, adhesion force measurements, and transmission electron microscopy (TEM). We demonstrate direct measurement of volume loss over the wear test and agreement between blind reconstruction and TEM imaging. The geometries of various types of tips were monitored over a scanning distance of approximately 100 mm. The results show multiple failure mechanisms for different materials, including nanoscale fracture of a monolithic Si tip upon initial engagement with the surface, film failure of a SiNx-coated Si tip, and gradual, progressive wear of monolithic SiNx tips consistent with atom-by-atom attrition. Overall, the method provides a quantitative and systematic process for examining tip degradation and nanoscale wear, and the experimental results illustrate the multiple mechanisms that may lead to tip failure.
原子力显微镜（AFM）是研究纳米尺度摩擦学（粘附、摩擦和润滑）的强大工具，并且正在成为纳米制造的关键工具。然而，纳米级磨损是传统 AFM 探针的一个关键限制，这些探针由硅和氮化硅（SiNx）制成。在这里，我们提出了一种系统地量化针尖磨损的方法，该方法包括在超纳米金刚石表面上进行顺序接触模式 AFM 扫描，同时使用盲目重建、粘附力测量和透射电子显微镜（TEM）间歇性地测量针尖特性。我们证明了在磨损测试过程中可以直接测量体积损失，并且盲目重建和 TEM 成像之间具有一致性。在大约 100mm 的扫描距离内监测了各种类型针尖的几何形状。结果表明，不同材料存在多种失效机制，包括与表面初始接触时单片 Si 针尖的纳米级断裂、SiNx 涂层 Si 针尖的薄膜失效以及与原子级侵蚀一致的单片 SiNx 针尖的渐进、渐进磨损。总体而言，该方法为检查针尖降解和纳米级磨损提供了一种定量和系统的过程，实验结果说明了可能导致针尖失效的多种机制。
