Effect of crystallographic orientation on the friction of copper and graphenized copper
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Effect of crystallographic orientation on the friction of copper and graphenized copper Y. C. Oh1, S. K. Kwon1, A. Minkow2, H. W. Park1, S. H. Kim1, H.-J. Fecht2, and A. Caron1,* 1 2
KOREATECH – Korea University of Technology and Education, Cheonan-Si 31253, Republic of Korea Institute of Functional Nanosystems, Ulm University, 89081 Ulm, Germany
Received: 5 May 2020
ABSTRACT
Accepted: 24 July 2020
In this work, we compare the friction behavior of single asperity contacts of a PtSi tip with copper and monolayered graphene on copper. For both PtSi/copper—and PtSi/graphenized copper tribological couples, we measured 16 differently oriented grains with three different sliding velocities as a function of the load by atomic force microscopy to assess the role of crystallographic orientation on friction and its rate dependence. We find that friction on copper is governed by shearing and does not depend on the crystallographic orientation but is significantly affected by the sliding velocity. We discuss this dependence based on contact aging in ambient conditions and shear strain rate sensitivity. In contrast, we find that friction of a graphene monolayer on copper is governed by puckering and depends both on the crystallographic orientation of the underlying grain and on the sliding velocity. We discuss these dependencies based on the orientational commensurability of the graphene lattice with the underlying copper crystallographic plane and on thermolubricity. Beyond their validity at the nanometer scale, our results are relevant to extend the understanding of friction between engineered surfaces at the macro- and micro-scale, where contacts initiate at nanometer-scale asperities.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
I. Introduction It is well established that friction has a limiting effect on the energy efficiency of machines with moving parts and their life time. Its understanding and control are thus of utmost importance for the design of
Handling Editor: Catalin Croitoru.
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https://doi.org/10.1007/s10853-020-05178-1
more efficient and environmentally friendly components and mechanical devices. Two fundamental mechanisms are associated with the friction and wear of metals: shearing and plowing [1]. In this respect, we have recently investigated the shearing friction between different metallic couples of gold, silver, and platinum silicide [2]. It was found that the
J Mater Sci
metallurgical affinity between metals significantly affects their tribological response. These findings are not new but important for materials selection in devices with components in relative motion. Also, we have studied the wear of different fcc metals and alloys by plowing [3, 4] and verified that the resistance of metals and alloys to wear depends on their mechanical properties, i.e., their hardness and their microstructural length scale. These results are not new and were already well established for macroscale wear. These results,
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