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A shear localization mechanism for lubricity of amorphous carbon materials

Amorphous carbon is one of the most lubricious materials known, but the mechanism is not well understood. It is counterintuitive that such a strong covalent solid could exhibit exceptional lubricity. A prevailing view is that lubricity of amorphous carbon results from chemical passivation of danglin...

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Autores principales: Ma, Tian-Bao, Wang, Lin-Feng, Hu, Yuan-Zhong, Li, Xin, Wang, Hui
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3888979/
https://www.ncbi.nlm.nih.gov/pubmed/24412998
http://dx.doi.org/10.1038/srep03662
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author Ma, Tian-Bao
Wang, Lin-Feng
Hu, Yuan-Zhong
Li, Xin
Wang, Hui
author_facet Ma, Tian-Bao
Wang, Lin-Feng
Hu, Yuan-Zhong
Li, Xin
Wang, Hui
author_sort Ma, Tian-Bao
collection PubMed
description Amorphous carbon is one of the most lubricious materials known, but the mechanism is not well understood. It is counterintuitive that such a strong covalent solid could exhibit exceptional lubricity. A prevailing view is that lubricity of amorphous carbon results from chemical passivation of dangling bonds on surfaces. Here we show instead that lubricity arises from shear induced strain localization, which, instead of homogeneous deformation, dominates the shearing process. Shear localization is characterized by covalent bond reorientation, phase transformation and structural ordering preferentially in a localized region, namely tribolayer, resulting in shear weakening. We further demonstrate an anomalous pressure induced transition from stick-slip friction to continuous sliding with ultralow friction, due to gradual clustering and layering of graphitic sheets in the tribolayer. The proposed shear localization mechanism sheds light on the mechanism of superlubricity, and would enrich our understanding of lubrication mechanism of a wide variety of amorphous materials.
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spelling pubmed-38889792014-01-15 A shear localization mechanism for lubricity of amorphous carbon materials Ma, Tian-Bao Wang, Lin-Feng Hu, Yuan-Zhong Li, Xin Wang, Hui Sci Rep Article Amorphous carbon is one of the most lubricious materials known, but the mechanism is not well understood. It is counterintuitive that such a strong covalent solid could exhibit exceptional lubricity. A prevailing view is that lubricity of amorphous carbon results from chemical passivation of dangling bonds on surfaces. Here we show instead that lubricity arises from shear induced strain localization, which, instead of homogeneous deformation, dominates the shearing process. Shear localization is characterized by covalent bond reorientation, phase transformation and structural ordering preferentially in a localized region, namely tribolayer, resulting in shear weakening. We further demonstrate an anomalous pressure induced transition from stick-slip friction to continuous sliding with ultralow friction, due to gradual clustering and layering of graphitic sheets in the tribolayer. The proposed shear localization mechanism sheds light on the mechanism of superlubricity, and would enrich our understanding of lubrication mechanism of a wide variety of amorphous materials. Nature Publishing Group 2014-01-13 /pmc/articles/PMC3888979/ /pubmed/24412998 http://dx.doi.org/10.1038/srep03662 Text en Copyright © 2014, Macmillan Publishers Limited. All rights reserved http://creativecommons.org/licenses/by-nc-nd/3.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/
spellingShingle Article
Ma, Tian-Bao
Wang, Lin-Feng
Hu, Yuan-Zhong
Li, Xin
Wang, Hui
A shear localization mechanism for lubricity of amorphous carbon materials
title A shear localization mechanism for lubricity of amorphous carbon materials
title_full A shear localization mechanism for lubricity of amorphous carbon materials
title_fullStr A shear localization mechanism for lubricity of amorphous carbon materials
title_full_unstemmed A shear localization mechanism for lubricity of amorphous carbon materials
title_short A shear localization mechanism for lubricity of amorphous carbon materials
title_sort shear localization mechanism for lubricity of amorphous carbon materials
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3888979/
https://www.ncbi.nlm.nih.gov/pubmed/24412998
http://dx.doi.org/10.1038/srep03662
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