Abstract
Using an atomic force microscope, a nanoscale wear characterization method has been applied to a commercial steel substrate AISI 52100, a common bearing material. Two wear mechanisms were observed by the presented method: atom attrition and elastoplastic ploughing. It is shown that not only friction can be used to classify the difference between these two mechanisms, but also the ‘degree of wear’. Archard's Law of adhesion shows good conformity to experimental data at the nanoscale for the elastoplastic ploughing mechanism. However, there is a distinct discontinuity between the two identified mechanisms of wear and their relation to the load and the removed volume. The length-scale effect of the material's hardness property plays an integral role in the relationship between the ‘degree of wear’ and load. The transition between wear mechanisms is hardness-dependent, as below a load threshold limited plastic deformation in the form of pile up is exhibited. It is revealed that the presented method can be used as a rapid wear characterization technique, but additional work is necessary to project individual asperity interaction observations to macroscale contacts.
Highlights
Tribological contacts can be attributed to approximately 23% of global energy consumption, with 3% recognized as directly wear-related [1]
This study concentrates on wear observation at a nanoscale that is less understood in the literature in comparison with macroscale wear characterization
Surface failures due to sliding wear mechanisms that lead to plastic deformation [3], cracking and material removal are the focus of this study rather than fatigue
Summary
Tribological contacts can be attributed to approximately 23% of global energy consumption, with 3% recognized as directly wear-related [1]. To characterize wear at the nano-length scale, one approach is to use an atomic force microscope (AFM) with an appropriately selected cantilever and tip The use of such an instrument forms the basis of the methodology in the current study. & Nosonovsky [8] further developed this work and applied it to wear coefficients The limitation of such relationships as indicated by Bushan & Nosonovsky is the lack of ability to measure the characteristic length scale, which enables the interpretation of nanoscale properties to the bulk material characteristic. Applying similar AFM wear characterization techniques to an engineering steel with grain boundaries will extend the applicability of the methodology to a wider range of commonly used materials These studies limited their scope of application of AFM scratching to interfacial phenomena of micro-electromechanical systems, and nanomachining [11,12,13,14]. The presented method will enable rapid and efficient wear characterization expandable across different scales of length
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