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Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
(a,b) The dependence of the friction forces along the x and y directions and the corresponding ΔFK at (a) 40 °C and (b) 80 °C on ε. Each data point in (a,b) represents the mean value of at least five measurements. Standard deviations are indicated by error bars.