Effects of Interfacial Bonding on Friction and Wear at Silica/Silica Interfaces

Li, Ao; Liu, Y.; Szlufarska, Izabela

doi:10.1007/s11249-014-0425-x

Cited by 59 publications

(86 citation statements)

References 40 publications

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“…Time-dependent formation of siloxane (Si-O-Si) bonds between a pair of opposing hydrolyzed silica groups (Si-OH) has been shown via atomic force microscopy to be a viable mechanism of frictional aging for nanoscale single-asperity silica-silica contacts (Li et al, 2011). Molecular simulations confirm the atomic force microscopy results and show that the number of siloxane bonds across a silica-silica interface increases linearly with the logarithm of contact time for an elastic contact (Li et al, 2014;Liu & Szlufarska, 2012). Thus, strong frictional aging occurs even in the absence of plastic deformation.…”

Section: Discussionmentioning

confidence: 82%

Constraints on the Physical Mechanism of Frictional Aging From Nanoindentation

Thom

Carpick

Goldsby

2018

Geophysical Research Letters

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The increase in the frictional strength of rocks with the time of quasi‐stationary contact, known as frictional aging, may ultimately determine whether unstable slip (i.e., earthquakes) can nucleate. In spite of its importance, the physical mechanism that underlies frictional aging in rocks is still uncertain. The widely held view is that aging results from an increase in contact area due to asperity creep. Here we show via nanoindentation testing that the hardness and creep rate of quartz are independent of relative humidity from <10−4% to 50%. This contrasts strongly with the standard interpretation of previous friction experiments on quartz tested over a similar humidity range, which reveal an absence of frictional aging for humidity <5%. Our results demonstrate that frictional aging in quartz cannot result from asperity creep and instead argue in favor of other mechanisms, including time‐dependent chemical bond formation or slip‐induced strengthening.

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Section: Discussionmentioning

confidence: 82%

Constraints on the Physical Mechanism of Frictional Aging From Nanoindentation

Thom

Carpick

Goldsby

2018

Geophysical Research Letters

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“…In our experiments we used temperature-dependent friction force microscopy [28] to measure the lateral forces at the interface between an AFM cantilever covered by SiO 2 and p-type (111) Si wafers with either a native oxide layer or a 300-nm oxide layer. Since humidity is known to have a strong influence on microscopic and macroscopic contact aging [12,13,29], all experiments were conducted under ultrahigh vacuum conditions.…”

Section: Resultsmentioning

confidence: 99%

“…The complexity of the process can be best understood starting from the idea that virtually any macroscopic surface exhibits a significant roughness, leading to a certain number of true contact points at the interface [10,11]. The dynamics of the junctions is then governed by a broad range of complex physical-chemical processes including bond formation [12][13][14][15][16], plastic flow [17], capillarity [18,19], and atomic attrition [20]. Through the time-dependent nature of these processes the contact strength is expected to increase logarithmically with time.…”

Section: Introductionmentioning

confidence: 99%

Temperature Activates Contact Aging in Silica Nanocontacts

et al. 2019

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Understanding the time evolution of contact strength in silica nanocontacts is of great fundamental and practical relevance in diverse areas like earthquake dynamics, wafer bonding mechanisms, as well as MEMS applications. The logarithmic increase of contact strength with hold time, termed contact aging, can be "quantitative" due to deformation creep in plastic contacts. An alternative mechanism, termed "qualitative aging," is the gradual change in interfacial chemistry, which so far was only observed in the presence of humidity. Here we present nanoscale friction experiments of dry silica contacts in ultrahigh vacuum that show a doubling of shear strength with time following a logarithmic law. We find that the aging rate scales linearly with temperature, and that shear stress shifts the relevant energy barriers. All-atom MD simulations provide a live picture of the bond formation dynamics occurring at the interface. Our experiments link contact aging to thermally activated bond formation, show that it exists even in the absence of water molecules, and demonstrate that this atomic aging mechanism can stretch over timescales up to several seconds. Qualitative contact aging is thus highly relevant for a broad variety of material combinations and conditions.

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“…Recently, the first-principles calculations indicated that covalent interfacial siloxane (Si-O-Si) bridges are formed at silica-silica interfaces [61,64]. FFM measurements of single-asperity silica-silica nanocontacts [30] found that two metastable states are involved in the process of formation and rupture of Si-O-Si bridges, which are the dangling state (Si-O-) and passivated state (Si-OH).…”

Section: Two-state Distributionmentioning

confidence: 99%

Load-velocity-temperature relationship in frictional response of microscopic contacts

Ouyang

Yang

et al. 2020

Journal of the Mechanics and Physics of Solids

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Frictional properties of interfaces with dynamic chemical bonds have been the subject of intensive experimental investigation and modelling, as it provides important insights into the molecular origin of the empirical rate and state laws, which have been highly successful in describing friction from nano to geophysical scales. Using previously developed theoretical approaches requires time-consuming simulations that are impractical for many realistic tribological systems. To solve this problem and set a framework for understanding microscopic mechanisms of friction at interfaces including multiple microscopic contacts, we developed an analytical approach for description of friction mediated by dynamical formation and rupture of microscopic interfacial contacts, which allows to calculate frictional properties on the time and length scales that are relevant to tribological experimental conditions. The model accounts for the presence of various types of contacts at the frictional interface and predicts novel dependencies of friction on sliding velocity, temperature and normal load, which are amenable to experimental observations. Our model predicts the velocitytemperature scaling, which relies on the interplay between the effects of shear and temperature on the rupture of interfacial contacts. The proposed scaling can be used to extrapolate the simulation results to a range of very low sliding velocities used in nanoscale friction experiments, which is still unreachable by simulations. For interfaces including two types of interfacial contacts with distinct properties, our model predicts novel double-peaked dependencies of friction on temperature and velocity. Considering friction force microscopy experiments (FFM), we found that the non-uniform distribution of normal load across the interface leads to a distribution of barrier heights for contact formation. The results obtained in this case allowed to reveal a mechanism of nonlinear dependence of friction on normal load observed in recent FFM experiments and predict the effect of normal load on velocity and temperature dependencies of friction. Our work provides a promising avenue for the interpretation of the experimental data on friction at interfaces including microscopic contacts and open new pathways for the rational control of the frictional response.

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Effects of Interfacial Bonding on Friction and Wear at Silica/Silica Interfaces

Cited by 59 publications

References 40 publications

Constraints on the Physical Mechanism of Frictional Aging From Nanoindentation

Constraints on the Physical Mechanism of Frictional Aging From Nanoindentation

Temperature Activates Contact Aging in Silica Nanocontacts

Load-velocity-temperature relationship in frictional response of microscopic contacts

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