1) M Zhukov, MS Hasan, P Nesterov, M Sabbouh, O Burdulenko, E V. Skorb, and M Nosonovsky* 2022 “Topological Data Analysis of Nanoscale Roughness in Brass Samples” ACS Appl. Mater. Interfaces 2021, https://doi.org/10.1021/acsami.1c20694
Rough surfaces possess complex topographies, which cannot be characterized by a single parameter. The selection of appropriate roughness parameters depends on a particular application. Large datasets representing surface topography possess orderliness, which can be expressed in terms of topological features in high-dimensional dataspaces reflecting properties such as anisotropy and the number of lay directions. The features are scale-dependent because both sampling length and resolution affect them. We study nanoscale surface roughness using 3 × 3, 4 × 4, and 5 × 5 pixel patches obtained from atomic force microscopy (AFM) images of brass (Cu Zn alloy) samples roughened by a sonochemical treatment. We calculate roughness parameters, correlation length, extremum point distribution, persistence diagrams, and barcodes. These parameters of interest are discussed and compared.
2) OV Tolochko, IA Kobykhno, SI Khashirova, AA Zhansitov, AD Breki, M Nosonovsky*, 2022, “Friction and Wear of Polyetheretherketone Samples With Different Melt Flow Indices” Journal of Tribology 2022, 144(6): 061705 (7 pages) https://doi.org/10.1115/1.4053092
Polyetheretherketone (PEEK) is a promising polymer material for tribological applications. Friction and wear tests of PEEK samples versus steel with different melt flow indices (MFI) were studied. The results showed dependencies of the friction force on the sliding velocity, either decreasing or increasing depending on whether the normal load exceeds the yield strength of the polymer. The data can be well fitted with the assumption of the two-component friction law involving the Amontons component and an adhesional component. With a decrease in MFI, i.e., with an increase in viscosity of polymer, the adhesive component of friction increases with increasing viscosity while the abrasive wear decreases. At high loads, the plastic displacement increases with an increase in the viscosity and plasticity of the polymer. The wear does not show a clear correlation with the viscosity.