What Governs Friction of Silicon Oxide in Humid Environment: Contact Area between Solids, Water Meniscus around the Contact, or Water Layer Structure?

Lei Chen, Chen Xiao, Bingjun Yu, Seong Kim, Linmao Qian

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

In order to understand the interfacial parameters governing the friction force (Ft) between silicon oxide surfaces in humid environment, the sliding speed (v) and relative humidity (RH) dependences of Ft were measured for a silica sphere (1 μm radius) sliding on a silicon oxide (SiOx) surface, using atomic force microscopy (AFM), and analyzed with a mathematical model describing interfacial contacts under a dynamic condition. Generally, Ft decreases logarithmically with increasing v to a cutoff value below which its dependence on interfacial chemistry and sliding condition is relatively weak. Above the cutoff value, the logarithmic v dependence could be divided into two regimes: (i) when RH is lower than 50%, Ft is a function of both v and RH; (ii) in contrast, at RH ≥ 50%, Ft is a function of v only, but not RH. These complicated v and RH dependences were hypothesized to originate from the structure of the water layer adsorbed on the surface and the water meniscus around the annulus of the contact area. This hypothesis was tested by analyzing Ft as a function of the water meniscus area (Am) and volume (Vm) estimated from a thermally activated water-bridge formation model. Surprisingly, it was found that Ft varies linearly with Vm and correlates poorly with Am at RH < 50%; and then its Vm dependence becomes weaker as RH increases above 50%. Comparing the friction data with the attenuated total reflection infrared (ATR-IR) spectroscopy analysis result of the adsorbed water layer, it appeared that the solidlike water layer structure formed on the silica surface plays a critical role in friction at RH < 50% and its contribution diminishes at RH ≥ 50%. These findings give a deeper insight into the role of water condensation in friction of the silicon oxide single asperity contact under ambient conditions.

Original languageEnglish (US)
Pages (from-to)9673-9679
Number of pages7
JournalLangmuir
Volume33
Issue number38
DOIs
StatePublished - Sep 26 2017

Fingerprint

menisci
Silicon oxides
silicon oxides
humidity
Atmospheric humidity
friction
Friction
Water
water
sliding
Silicon Dioxide
cut-off
Silica
silicon dioxide
annuli
Surface chemistry
surface water
Condensation
Infrared spectroscopy
Atomic force microscopy

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

Cite this

@article{9ee983e9bb79456ba45a99919ec482e5,
title = "What Governs Friction of Silicon Oxide in Humid Environment: Contact Area between Solids, Water Meniscus around the Contact, or Water Layer Structure?",
abstract = "In order to understand the interfacial parameters governing the friction force (Ft) between silicon oxide surfaces in humid environment, the sliding speed (v) and relative humidity (RH) dependences of Ft were measured for a silica sphere (1 μm radius) sliding on a silicon oxide (SiOx) surface, using atomic force microscopy (AFM), and analyzed with a mathematical model describing interfacial contacts under a dynamic condition. Generally, Ft decreases logarithmically with increasing v to a cutoff value below which its dependence on interfacial chemistry and sliding condition is relatively weak. Above the cutoff value, the logarithmic v dependence could be divided into two regimes: (i) when RH is lower than 50{\%}, Ft is a function of both v and RH; (ii) in contrast, at RH ≥ 50{\%}, Ft is a function of v only, but not RH. These complicated v and RH dependences were hypothesized to originate from the structure of the water layer adsorbed on the surface and the water meniscus around the annulus of the contact area. This hypothesis was tested by analyzing Ft as a function of the water meniscus area (Am) and volume (Vm) estimated from a thermally activated water-bridge formation model. Surprisingly, it was found that Ft varies linearly with Vm and correlates poorly with Am at RH < 50{\%}; and then its Vm dependence becomes weaker as RH increases above 50{\%}. Comparing the friction data with the attenuated total reflection infrared (ATR-IR) spectroscopy analysis result of the adsorbed water layer, it appeared that the solidlike water layer structure formed on the silica surface plays a critical role in friction at RH < 50{\%} and its contribution diminishes at RH ≥ 50{\%}. These findings give a deeper insight into the role of water condensation in friction of the silicon oxide single asperity contact under ambient conditions.",
author = "Lei Chen and Chen Xiao and Bingjun Yu and Seong Kim and Linmao Qian",
year = "2017",
month = "9",
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language = "English (US)",
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pages = "9673--9679",
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publisher = "American Chemical Society",
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What Governs Friction of Silicon Oxide in Humid Environment : Contact Area between Solids, Water Meniscus around the Contact, or Water Layer Structure? / Chen, Lei; Xiao, Chen; Yu, Bingjun; Kim, Seong; Qian, Linmao.

In: Langmuir, Vol. 33, No. 38, 26.09.2017, p. 9673-9679.

Research output: Contribution to journalArticle

TY - JOUR

T1 - What Governs Friction of Silicon Oxide in Humid Environment

T2 - Contact Area between Solids, Water Meniscus around the Contact, or Water Layer Structure?

AU - Chen, Lei

AU - Xiao, Chen

AU - Yu, Bingjun

AU - Kim, Seong

AU - Qian, Linmao

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N2 - In order to understand the interfacial parameters governing the friction force (Ft) between silicon oxide surfaces in humid environment, the sliding speed (v) and relative humidity (RH) dependences of Ft were measured for a silica sphere (1 μm radius) sliding on a silicon oxide (SiOx) surface, using atomic force microscopy (AFM), and analyzed with a mathematical model describing interfacial contacts under a dynamic condition. Generally, Ft decreases logarithmically with increasing v to a cutoff value below which its dependence on interfacial chemistry and sliding condition is relatively weak. Above the cutoff value, the logarithmic v dependence could be divided into two regimes: (i) when RH is lower than 50%, Ft is a function of both v and RH; (ii) in contrast, at RH ≥ 50%, Ft is a function of v only, but not RH. These complicated v and RH dependences were hypothesized to originate from the structure of the water layer adsorbed on the surface and the water meniscus around the annulus of the contact area. This hypothesis was tested by analyzing Ft as a function of the water meniscus area (Am) and volume (Vm) estimated from a thermally activated water-bridge formation model. Surprisingly, it was found that Ft varies linearly with Vm and correlates poorly with Am at RH < 50%; and then its Vm dependence becomes weaker as RH increases above 50%. Comparing the friction data with the attenuated total reflection infrared (ATR-IR) spectroscopy analysis result of the adsorbed water layer, it appeared that the solidlike water layer structure formed on the silica surface plays a critical role in friction at RH < 50% and its contribution diminishes at RH ≥ 50%. These findings give a deeper insight into the role of water condensation in friction of the silicon oxide single asperity contact under ambient conditions.

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