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Chin. Phys. B, 2009, Vol. 18(1): 231-237    DOI: 10.1088/1674-1056/18/1/038
CLASSICAL AREAS OF PHENOMENOLOGY Prev   Next  

Effect of micro-dimple patterns on capillary pull-off force and friction force of silicon surface

Zhang Xiang-Jun(张向军)a)b), Dong Yun-Kai (董云开)a), Liu Yong-He(刘永合)b), and J. A. Schaeferb)
a State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China; b Institute of Physics and Center of Micro/nano Technology, Technich University of Ilmenau, PF 100565, Germany
Abstract  A microtribometer is used to measure and compare pull-off forces and friction forces exerted on (a) micro-dimpled silicon surfaces, (b) bare silicon surfaces, and (c) octadecyltrichlorosilane (OTS) treated silicon surfaces at different relative humidity (RH) levels separately. It is found that above a critical RH level, the capillary pull-off force increases abruptly and that the micro-dimple textured surface has a lower critical RH value as well as a higher pull-off force value than the other two surfaces. A micro topography parameter, namely sidewall area ratio, is found to play a major role in controlling the capillary pull-off force. Furthermore, micro-dimpled silicon surface is also proved to be not sensitive to variation in RH level, and can realize a stable and decreased friction coefficient compared with un-textured silicon surfaces. The reservoir-like function of micro dimples is considered to weaken or avoid the breakage effect of liquid bridges at different RH levels, thereby maintaining a stable frictional behaviour.
Keywords:  micro-dimpled surface      capillary pull-off force      frictional property      relative humidity  
Received:  19 May 2008      Revised:  13 August 2008      Accepted manuscript online: 
PACS:  68.03.Kn (Dynamics (capillary waves))  
  68.08.-p (Liquid-solid interfaces)  
  68.15.+e (Liquid thin films)  
Fund: Project supported by the National Natural Science Foundation of China (Grant Nos 50575123 and 50730007), and China Scholarship Council (CSC) and German Research Foundation (DFG).

Cite this article: 

Zhang Xiang-Jun(张向军), Dong Yun-Kai (董云开), Liu Yong-He(刘永合), and J. A. Schaefer Effect of micro-dimple patterns on capillary pull-off force and friction force of silicon surface 2009 Chin. Phys. B 18 231

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