Wear, Plasticity, and Rehybridization in Tetrahedral Amorphous Carbon

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• 作者：Tim Kunze (1)
  Matthias Posselt (2)
  Sibylle Gemming (2)
  Gotthard Seifert (1)
  Andrew R. Konicek (3)
  Robert W. Carpick (3)
  Lars Pastewka (4)
  Michael Moseler (4)
  
• 关键词：Wear ; Plasticity ; Rehybridization ; ta ; C ; Tribology
• 刊名：Tribology Letters
• 出版年：2014
• 出版时间：January 2014
• 年：2014
• 卷：53
• 期：1
• 页码：119-126
• 全文大小：524 KB
• 作者单位：Tim Kunze (1)
  Matthias Posselt (2)
  Sibylle Gemming (2)
  Gotthard Seifert (1)
  Andrew R. Konicek (3)
  Robert W. Carpick (3)
  Lars Pastewka (4)
  Michael Moseler (4)
  
  1. Theoretical Chemistry, University of Technology Dresden, 01662, Dresden, Germany
  2. Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 51 01 19, 01314, Dresden, Germany
  3. Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA, 19104, USA
  4. Fraunhofer-Institut f眉r Werkstoffmechanik IWM, W枚hlerstrasse 11, 79108, Freiburg, Germany
  
• ISSN：1573-2711

文摘

Wear in self-mated tetrahedral amorphous carbon (ta-C) films is studied by molecular dynamics and near-edge X-ray absorption fine structure spectroscopy. Both theory and experiment demonstrate the formation of a soft amorphous carbon (a-C) layer with increased sp2 content, which grows faster than an a-C tribolayer found on self-mated diamond sliding under similar conditions. The faster $\hbox{sp}^{3} \rightarrow\,\hbox{ sp}^{2}$ transition in ta-C is explained by easy breaking of prestressed bonds in a finite, nanoscale ta-C region, whereas diamond amorphization occurs at an atomically sharp interface. A detailed analysis of the underlying rehybridization mechanism reveals that the $\hbox{sp}^{3}\, \rightarrow\hbox{ sp}^{2}$ transition is triggered by plasticity in the adjacent a-C. Rehybridization therefore occurs in a region that has not yet experienced plastic yield. The resulting soft a-C tribolayer is interpreted as a precursor to the experimentally observed wear.