Logarithmic decrease of adhesion force with lateral dynamic revealed by an AFM cantilever at different humidities |
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Authors: | Tianmao Lai Wanglong Zhan Ping Huang |
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Affiliation: | 1. State Key Laboratory of Tribology, Tsinghua University, Beijing, China;2. School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, China |
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Abstract: | Adhesion forces between a tipless cantilever and an Au film were determined to investigate the influence of lateral velocity by recording force curves with an atomic force microscope at 20%–90% relative humidities. The sample was moved laterally, forth and back, with a frequency of 0.001–100 Hz and scan distances of 0.8, 8, and 80 μm to achieve a velocity ranging over 7 orders of magnitude. Experimental results show that at low lateral velocities (between 1.6 nm/s and 1–10 μm/s), the adhesion force either increases or decreases or remains stable with the lateral velocity without a certain characteristic trend. However, after a critical velocity, the adhesion force decreases logarithmically with the lateral velocity (between 1–10 and 16,000 μm/s). The decreasing magnitude can be as large as 97.3% of the maximum adhesion force. This decrease is well-explained by the contact time dependence of water bridges formed by capillary condensation. |
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Keywords: | Adhesion by physical adsorption atomic force microscope capillary condensation coatings pull-off force sliding velocity |
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