Comparison of wear methods at nanoscale: line scanning and area scanning

Two wear methods, line scanning and area scanning, were investigated to clarify their effect on wear experimental results at nanoscale. Wear tests of pure copper against diamond tip in vacuum and silicon against SiO2 tip in water were performed using atomic force microscopy. Results show that two scanning methods can result in marked differences in experimental results for either pure mechanical wear or tribochemical wear. The variation in wear rate with sliding cycle indicates that the nanowear of material surface is a dynamic evolution process, which highly depends on the scanning methods. Line scanning is usually a simple and efficient wear method that can markedly change the interfacial contact profile and even induce a regional “work hardening” on the contact interface. By tuning the scan overlap rate, area scanning can reduce the influence of thermal drift of instrument and local defects of samples, as well as better present wear behaviors of material surface in initial wear stage. This study not only elucidates the importance of choosing wear methods as well as scan parameters in nanotribological investigations, but also provides an in-depth understanding of nanowear behaviors of material surfaces.